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2021 Volume 32 Issue 2
2021, 32(2): 591-593
doi: 10.1016/j.cclet.2020.11.042
Abstract:
Herein, we directly prepared white fluorescent CDs (W-CDs) using 1,6-dihydroxynaphthalene (1,6-DHN) and L-asparagine (L-Asn) as carbon sources through a simple solvent-free method. As-prepared W-CDs can be obtained in high yield (95%). A relative pure white LEDs (WLEDs) were fabricated with Commission Internationale de L'Eclairage (CIE) coordinates of (0.32, 0.31). As-prepared W-CDs will have promising future for a wide range of optoelectronic devices.
Herein, we directly prepared white fluorescent CDs (W-CDs) using 1,6-dihydroxynaphthalene (1,6-DHN) and L-asparagine (L-Asn) as carbon sources through a simple solvent-free method. As-prepared W-CDs can be obtained in high yield (95%). A relative pure white LEDs (WLEDs) were fabricated with Commission Internationale de L'Eclairage (CIE) coordinates of (0.32, 0.31). As-prepared W-CDs will have promising future for a wide range of optoelectronic devices.
2021, 32(2): 594-597
doi: 10.1016/j.cclet.2020.11.047
Abstract:
The recent boom in large-scale energy storage system promotes the development of lithium-oxygen batteries because of their high theoretical energy density. However, their applications are still limited by the sluggish kinetic, insoluble discharge product deposition and the undesired parasitic reaction. Herein, the free-standing nitrogen doped reduced graphene oxide/Co(OH)2 (NRGO/Co(OH)2) composite films were prepared by a facile hydrothermal method. The NRGO/Co(OH)2 composite films display interconnected three-dimensional conductive network, which can not only promote the diffusion of O2 and the transport of electrolyte ions, but also provide abundant storage space for discharge products. Moreover, the introduction of nitrogen-containing functional groups results in improved conductivity and electron adsorption ability, which can facilitate electron transport and enhance the surface catalytic activity. Combining with excellent catalytic performance, the lithium-oxygen batteries with NRGO/Co(OH)2 composite film cathodes deliver low charge overpotential and excellent cycling performance.
The recent boom in large-scale energy storage system promotes the development of lithium-oxygen batteries because of their high theoretical energy density. However, their applications are still limited by the sluggish kinetic, insoluble discharge product deposition and the undesired parasitic reaction. Herein, the free-standing nitrogen doped reduced graphene oxide/Co(OH)2 (NRGO/Co(OH)2) composite films were prepared by a facile hydrothermal method. The NRGO/Co(OH)2 composite films display interconnected three-dimensional conductive network, which can not only promote the diffusion of O2 and the transport of electrolyte ions, but also provide abundant storage space for discharge products. Moreover, the introduction of nitrogen-containing functional groups results in improved conductivity and electron adsorption ability, which can facilitate electron transport and enhance the surface catalytic activity. Combining with excellent catalytic performance, the lithium-oxygen batteries with NRGO/Co(OH)2 composite film cathodes deliver low charge overpotential and excellent cycling performance.
2021, 32(2): 598-603
doi: 10.1016/j.cclet.2020.11.041
Abstract:
Amorphous silicon (a-Si) is one of the most promising anode-materials for the lithium-ion battery owing to its large capacity and superior fracture resistance. However, a-Si is usually fabricated with the sophisticated chemical vapor deposition or pulse laser deposition in a limited scale. In this work, we have successfully prepared a-Si spheres (~200 nm) by reducing the TiO2-coated silica spheres with Al powders in the molten salts at 300 ℃. The coated TiO2 layer acts as a protective layer for structural maintenance during the reduction and a precursor for doping. The doped Ti element may suppress the crystal growth of Si to facilitate the formation of a-Si. The observation with in-situ transmission electron microscopy (TEM) further reveals that lithiation kinetics of the synthesized a-Si is controlled by the interfacial reaction. The Li+ diffusivity in a-Si determined from the observation is in the order of 10−14 cm2/s. The anode of a-Si spheres together with crystalline Si nanoparticles exhibits excellent electrochemical performance, delivering a reversible capacity of 1604 mAh/g at 4 A/g and a capacity retention of 78.3% after 500 cycles. The low temperature reduction process reported in this study provides a low-cost method to fabricate a-Si nanostructures as high-capacity durable anode materials
Amorphous silicon (a-Si) is one of the most promising anode-materials for the lithium-ion battery owing to its large capacity and superior fracture resistance. However, a-Si is usually fabricated with the sophisticated chemical vapor deposition or pulse laser deposition in a limited scale. In this work, we have successfully prepared a-Si spheres (~200 nm) by reducing the TiO2-coated silica spheres with Al powders in the molten salts at 300 ℃. The coated TiO2 layer acts as a protective layer for structural maintenance during the reduction and a precursor for doping. The doped Ti element may suppress the crystal growth of Si to facilitate the formation of a-Si. The observation with in-situ transmission electron microscopy (TEM) further reveals that lithiation kinetics of the synthesized a-Si is controlled by the interfacial reaction. The Li+ diffusivity in a-Si determined from the observation is in the order of 10−14 cm2/s. The anode of a-Si spheres together with crystalline Si nanoparticles exhibits excellent electrochemical performance, delivering a reversible capacity of 1604 mAh/g at 4 A/g and a capacity retention of 78.3% after 500 cycles. The low temperature reduction process reported in this study provides a low-cost method to fabricate a-Si nanostructures as high-capacity durable anode materials
2021, 32(2): 604-608
doi: 10.1016/j.cclet.2020.11.044
Abstract:
Two new hydrostable two-dimensional (2D) uranyl coordination complexes [(UO2)5(μ3-O)2(nbca)2]·7H2O (1) and [(UO2)3(nbca)2(H2O)3]·2H2O (2) (H3nbca = 5-nitro-1,2,3-benzenetricarboxylic acid) were hydrothermal synthesized. Single-crystal structural refinements reveal that both of the two complexes were formed by the packing of 2D uranyl coordination sheets via the hydrogen bonds. The nbca ligand coordinating to the uranyl polyhedron centers constructed the 2D sheets. There are UO8 hexagonal bipyramids and UO7 pentagonal bipyramids in 1 while only UO7 pentagonal bipyramids in 2. Photocatalytic degradation of rhodamine B (RhB) in aqueous solution was studied. Complex 2 possesses better performance than 1 with 96.2 % of the RhB was degraded in only 60 min. Mechanism studies reveal that the dissolved oxygens are essential to the RhB degradation. The photocurrent density of 2 is more stable than that of 1, which indicating the stronger ability to separate photoexcited electrons and hole pairs of 2.
Two new hydrostable two-dimensional (2D) uranyl coordination complexes [(UO2)5(μ3-O)2(nbca)2]·7H2O (1) and [(UO2)3(nbca)2(H2O)3]·2H2O (2) (H3nbca = 5-nitro-1,2,3-benzenetricarboxylic acid) were hydrothermal synthesized. Single-crystal structural refinements reveal that both of the two complexes were formed by the packing of 2D uranyl coordination sheets via the hydrogen bonds. The nbca ligand coordinating to the uranyl polyhedron centers constructed the 2D sheets. There are UO8 hexagonal bipyramids and UO7 pentagonal bipyramids in 1 while only UO7 pentagonal bipyramids in 2. Photocatalytic degradation of rhodamine B (RhB) in aqueous solution was studied. Complex 2 possesses better performance than 1 with 96.2 % of the RhB was degraded in only 60 min. Mechanism studies reveal that the dissolved oxygens are essential to the RhB degradation. The photocurrent density of 2 is more stable than that of 1, which indicating the stronger ability to separate photoexcited electrons and hole pairs of 2.
2021, 32(2): 668-671
doi: 10.1016/j.cclet.2020.06.008
Abstract:
Atkamine is a complex marine pyrroloiminoquinone alkaloid that comprises a heptacyclic scaffold bearing five different heterocycles and four contiguous stereocenters, and therefore it is a highly challenging target for synthetic chemists. We herein reported a modular synthetic strategy toward this alkaloid, featuring a formal [5 + 2] annulation and an asymmetric Michael addition. The efficient synthesis of the long-chain aliphatic aldehyde and chiral amino acetal fragments have been achieved. A simplified tetracyclic intermediate bearing the core structure of atkamine has been successfully constructed through the formal [5 + 2] annulation.
Atkamine is a complex marine pyrroloiminoquinone alkaloid that comprises a heptacyclic scaffold bearing five different heterocycles and four contiguous stereocenters, and therefore it is a highly challenging target for synthetic chemists. We herein reported a modular synthetic strategy toward this alkaloid, featuring a formal [5 + 2] annulation and an asymmetric Michael addition. The efficient synthesis of the long-chain aliphatic aldehyde and chiral amino acetal fragments have been achieved. A simplified tetracyclic intermediate bearing the core structure of atkamine has been successfully constructed through the formal [5 + 2] annulation.
2021, 32(2): 672-675
doi: 10.1016/j.cclet.2020.06.010
Abstract:
An unprecedented chiral secondary amine-catalyzed [3 + 3] annulation of isatin N,N'-cyclic azomethine imines with α,β-unsaturated aldehydes was developed. This strategy allowed the construction of structurally novel spiro N-heterocyclic oxindole derivatives in good yields (up to 91%) and good to excellent enantioselectivities (up to >99% ee), albeit with modest diastereoselectivities (up to 3.1:1 dr).
An unprecedented chiral secondary amine-catalyzed [3 + 3] annulation of isatin N,N'-cyclic azomethine imines with α,β-unsaturated aldehydes was developed. This strategy allowed the construction of structurally novel spiro N-heterocyclic oxindole derivatives in good yields (up to 91%) and good to excellent enantioselectivities (up to >99% ee), albeit with modest diastereoselectivities (up to 3.1:1 dr).
2021, 32(2): 676-680
doi: 10.1016/j.cclet.2020.06.022
Abstract:
Monodispersed palladium phosphide (Pd3P) (5.2 ±0.5 nm) was firstly applied to photocatalytic Suzuki coupling reaction under visible light irradiation with CdS nanoflake as a photosensitizer. This heterogeneous system exhibited high yields to corresponding products and excellent stability in alcohol solvent at room temperature.
Monodispersed palladium phosphide (Pd3P) (5.2 ±0.5 nm) was firstly applied to photocatalytic Suzuki coupling reaction under visible light irradiation with CdS nanoflake as a photosensitizer. This heterogeneous system exhibited high yields to corresponding products and excellent stability in alcohol solvent at room temperature.
2021, 32(2): 681-684
doi: 10.1016/j.cclet.2020.06.026
Abstract:
Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed, featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor. When combined, the two components can undergo visible light-induced single-electron transfer, and serve as a versatile and effective alkyl radical generator.
Metal-free anti-Markovnikov hydroalkylation of unactivated alkenes with cyanoacetate has been developed, featuring the use of a dual-component initiator containing an organic photocatalyst and a radical precursor. When combined, the two components can undergo visible light-induced single-electron transfer, and serve as a versatile and effective alkyl radical generator.
2021, 32(2): 685-690
doi: 10.1016/j.cclet.2020.06.027
Abstract:
An efficient, sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons (Co@NCs) via pyrolysis of aniline-modified ZIFs, has been demonstrated. Aniline can coordinate and absorb on the surface of ZIF (ZIF-CoZn3-PhA), accelerate the precipitation of ZIFs, thus resulting in smaller ZIF particle size. Meanwhile, the aniline on the surface of ZIF-CoZn3-PhA promotes the formation of the protective carbon shell and smaller Co nanoparticles, and increases nitrogen content of the catalyst. Because of these properties of Co@NC-PhA-3, the oxidative esterification of 5-hydroxyme-thylfurfural can be carried out under ambient conditions. According to our experimental and computational results, a synergistic catalytic effect between CoNx sites and Co nanoparticles has been established, in which both Co nanoparticles and CoNx can activate O2 while Co nanoparticles bind and oxidize HMF. Moreover, the formation and release of active oxygen species in CoNx sites are reinforced by the electronic interaction between Co nanoparticles and CoNx.
An efficient, sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons (Co@NCs) via pyrolysis of aniline-modified ZIFs, has been demonstrated. Aniline can coordinate and absorb on the surface of ZIF (ZIF-CoZn3-PhA), accelerate the precipitation of ZIFs, thus resulting in smaller ZIF particle size. Meanwhile, the aniline on the surface of ZIF-CoZn3-PhA promotes the formation of the protective carbon shell and smaller Co nanoparticles, and increases nitrogen content of the catalyst. Because of these properties of Co@NC-PhA-3, the oxidative esterification of 5-hydroxyme-thylfurfural can be carried out under ambient conditions. According to our experimental and computational results, a synergistic catalytic effect between CoNx sites and Co nanoparticles has been established, in which both Co nanoparticles and CoNx can activate O2 while Co nanoparticles bind and oxidize HMF. Moreover, the formation and release of active oxygen species in CoNx sites are reinforced by the electronic interaction between Co nanoparticles and CoNx.
2021, 32(2): 691-694
doi: 10.1016/j.cclet.2020.06.028
Abstract:
Transition metal-catalyzed carbene transfer reaction is one of the most notable advances for C−C bond formation reactionsduring the past decade, which has been widely employed in the preparation of C3-substituted indoles. Here, we described an efficient example of catalyst- and metal-free aminoboration of alkynes and C−C bond formation with diazo compounds to produce C3-substituted indoles. Diverse alkynylanilines and diazo compounds can be utilized for this tandem transformation under mild reaction conditions, resulting in broad functional group compatibility. Additionally, this metal-free strategy can be extended to construct substituted benzofurans.
Transition metal-catalyzed carbene transfer reaction is one of the most notable advances for C−C bond formation reactionsduring the past decade, which has been widely employed in the preparation of C3-substituted indoles. Here, we described an efficient example of catalyst- and metal-free aminoboration of alkynes and C−C bond formation with diazo compounds to produce C3-substituted indoles. Diverse alkynylanilines and diazo compounds can be utilized for this tandem transformation under mild reaction conditions, resulting in broad functional group compatibility. Additionally, this metal-free strategy can be extended to construct substituted benzofurans.
2021, 32(2): 695-699
doi: 10.1016/j.cclet.2020.06.011
Abstract:
Acid-controlled, chemodivergent and redox-neutral annulations for the synthesis of isocoumarins and isoquinolinones have been realized via Rh(III)-catalyzed C—H activation. Diazo compounds act as a carbene precursor, and coupling occurs in one-pot process, where adipic acid and trimethylacetic acid promote chemodivergent cyclizations.
Acid-controlled, chemodivergent and redox-neutral annulations for the synthesis of isocoumarins and isoquinolinones have been realized via Rh(III)-catalyzed C—H activation. Diazo compounds act as a carbene precursor, and coupling occurs in one-pot process, where adipic acid and trimethylacetic acid promote chemodivergent cyclizations.
2021, 32(2): 700-702
doi: 10.1016/j.cclet.2020.06.019
Abstract:
Chemoselective amine bioconjugation has long been a challenge for native protein modification. Inspired by Thiele's seminal discovery, Li and co-workers recently developed an ortho-phthalaldehyde (OPA) based reagent for labeling the amino group of a protein. Here we report an expeditious and scalable synthesis of a Li—Thiele reagent featuring an arene construction strategy. The reagent contains an alkyne side chain as a handle for secondary modification.
Chemoselective amine bioconjugation has long been a challenge for native protein modification. Inspired by Thiele's seminal discovery, Li and co-workers recently developed an ortho-phthalaldehyde (OPA) based reagent for labeling the amino group of a protein. Here we report an expeditious and scalable synthesis of a Li—Thiele reagent featuring an arene construction strategy. The reagent contains an alkyne side chain as a handle for secondary modification.
2021, 32(2): 703-707
doi: 10.1016/j.cclet.2020.06.025
Abstract:
Two n-butoxy-encapsulated dendritic thermally activated delayed fluorescent (TADF) emitters (namely O-D1 and O-D2) with the first-/second-generation carbazoledendrons are designed and synthesized via CN coupling between carbazoledendrons and 2,4,6-tris(4-bromophenyl)-1,3,5-triazine core. It is found that, compared with the commonly-used tert-butyl groups, the use of n-butoxy encapsulation groups can lead to smallersinglet-triplet energy gap for the dendrimers, producing stronger TADF effect together with faster reverse intersystem crossing process. Solution-processed TADF organic light-emitting diodes (OLEDs) utilizingalkoxy-encapsulated dendrimers O-D1 and O-D2 as emitters exhibitstate-of-the-art device efficiency withthe maximum external quantum efficiency up to 16.8% and 20.6%, respectively, which are ~1.6 and ~2.0 times that of the tert-butyl-encapsulated counterparts. These results suggest that alkoxy encapsulation of the carbazole-based TADF dendrimers can be a promising approach for developing highly efficient emitters for solution-processed OLEDs.
Two n-butoxy-encapsulated dendritic thermally activated delayed fluorescent (TADF) emitters (namely O-D1 and O-D2) with the first-/second-generation carbazoledendrons are designed and synthesized via CN coupling between carbazoledendrons and 2,4,6-tris(4-bromophenyl)-1,3,5-triazine core. It is found that, compared with the commonly-used tert-butyl groups, the use of n-butoxy encapsulation groups can lead to smallersinglet-triplet energy gap for the dendrimers, producing stronger TADF effect together with faster reverse intersystem crossing process. Solution-processed TADF organic light-emitting diodes (OLEDs) utilizingalkoxy-encapsulated dendrimers O-D1 and O-D2 as emitters exhibitstate-of-the-art device efficiency withthe maximum external quantum efficiency up to 16.8% and 20.6%, respectively, which are ~1.6 and ~2.0 times that of the tert-butyl-encapsulated counterparts. These results suggest that alkoxy encapsulation of the carbazole-based TADF dendrimers can be a promising approach for developing highly efficient emitters for solution-processed OLEDs.
2021, 32(2): 708-712
doi: 10.1016/j.cclet.2020.07.026
Abstract:
Multiple hydrogen bonds containing nucleophilic phosphines derived from dipeptide dual-reagents catalyzed asymmetric Michael addition reactions between indene esters and activated olefins in high yields and good to excellent enantioselectivities under mild reaction conditions. The success of current highly selective reactions should provide inspiration for expansion to other reactions and would open up new paradigms for the synthesis of indanone derivatives bearing chiral quaternary carbon centers.
Multiple hydrogen bonds containing nucleophilic phosphines derived from dipeptide dual-reagents catalyzed asymmetric Michael addition reactions between indene esters and activated olefins in high yields and good to excellent enantioselectivities under mild reaction conditions. The success of current highly selective reactions should provide inspiration for expansion to other reactions and would open up new paradigms for the synthesis of indanone derivatives bearing chiral quaternary carbon centers.
2021, 32(2): 713-716
doi: 10.1016/j.cclet.2020.07.005
Abstract:
A simultaneous C2-H arylation and C8-H alkylation of naphthalene ring has been achieved by palladium-catalyzed cascade reaction of N-(2-halophenyl)-2-(naphthalen-1-yl)acrylamides with aryl iodides, which provides an efficient method for synthesizing various aryl-substituted spirocyclic oxindoles. The protocol enables three CC bonds formation via an intramolecular Heck reaction and sequentially regioselective CH bond activation.
A simultaneous C2-H arylation and C8-H alkylation of naphthalene ring has been achieved by palladium-catalyzed cascade reaction of N-(2-halophenyl)-2-(naphthalen-1-yl)acrylamides with aryl iodides, which provides an efficient method for synthesizing various aryl-substituted spirocyclic oxindoles. The protocol enables three CC bonds formation via an intramolecular Heck reaction and sequentially regioselective CH bond activation.
2021, 32(2): 717-720
doi: 10.1016/j.cclet.2020.07.006
Abstract:
Pincer complexes are widely used in organometallic and coordination chemistry. The role of antimony as a central donor atom in pincer ligands has been extensively explored in recent years. Although phenylenediamine derived PXP (X = B, Al, C, Si, Ge, Sn, N) type ligands exhibit diverse reactivity, analogues species based on antimony have been reported less frequently. Herein, we report a new PSbP complex and evaluate its reactivity. These species will broaden the family of phenylenediamine derived pincer complexes.
Pincer complexes are widely used in organometallic and coordination chemistry. The role of antimony as a central donor atom in pincer ligands has been extensively explored in recent years. Although phenylenediamine derived PXP (X = B, Al, C, Si, Ge, Sn, N) type ligands exhibit diverse reactivity, analogues species based on antimony have been reported less frequently. Herein, we report a new PSbP complex and evaluate its reactivity. These species will broaden the family of phenylenediamine derived pincer complexes.
2021, 32(2): 721-724
doi: 10.1016/j.cclet.2020.07.007
Abstract:
In many reactions involving selenosulfonate or thiosulfonate, the sulfone group often leaves in form of benzenesulfinic acid or sodium benzenesulfinate. A one-pot two-step reaction of selenosulfonate with isocyanides and allyl alcohol under aqueous conditions to afford selenocarbamates and allyl sulfone compounds is reported. The sulfinic acid as the first-step side product is converted to the allyl sulfone compound by water promoted reaction with allyl alcohol. Water acts as both an oxygen source of selenocarbamates and as a promoter to drive the second step reaction. The reactions have the advantages of mild conditions, green, environment-friendly, and high atomic economy.
In many reactions involving selenosulfonate or thiosulfonate, the sulfone group often leaves in form of benzenesulfinic acid or sodium benzenesulfinate. A one-pot two-step reaction of selenosulfonate with isocyanides and allyl alcohol under aqueous conditions to afford selenocarbamates and allyl sulfone compounds is reported. The sulfinic acid as the first-step side product is converted to the allyl sulfone compound by water promoted reaction with allyl alcohol. Water acts as both an oxygen source of selenocarbamates and as a promoter to drive the second step reaction. The reactions have the advantages of mild conditions, green, environment-friendly, and high atomic economy.
2021, 32(2): 725-728
doi: 10.1016/j.cclet.2020.07.039
Abstract:
The effect of cucurbit[7]uril (CB[7]) on fluorescence properties and biocompatibility of the bis-viologen biphenyl molecule (BPV22+) was investigated by using 1H NMR spectroscopy, fluorescence emission titration, and in vitro cytotoxicity experiments. CB[7] can be combined with BPV22+ in a stoichiometric ratio of 1:1 and 2:1. After the formation of host-guest complex, the fluorescence emission intensity of BPV22+ increased significantly, and the emission spectrum blue shifted. Meanwhile, the host-guest complexes showed better biocompatibility than BPV22+ in cell cytotoxicity studies. Results of this paper lay a foundation for the development of host-guest type of fluorescent probes, biological imaging and so forth.
The effect of cucurbit[7]uril (CB[7]) on fluorescence properties and biocompatibility of the bis-viologen biphenyl molecule (BPV22+) was investigated by using 1H NMR spectroscopy, fluorescence emission titration, and in vitro cytotoxicity experiments. CB[7] can be combined with BPV22+ in a stoichiometric ratio of 1:1 and 2:1. After the formation of host-guest complex, the fluorescence emission intensity of BPV22+ increased significantly, and the emission spectrum blue shifted. Meanwhile, the host-guest complexes showed better biocompatibility than BPV22+ in cell cytotoxicity studies. Results of this paper lay a foundation for the development of host-guest type of fluorescent probes, biological imaging and so forth.
2021, 32(2): 729-734
doi: 10.1016/j.cclet.2020.08.035
Abstract:
Smart strategies that can decrease the side effect and enhance the therapeutic efficacy of chemotherapy are in urgent need to meet the special demands of cancer therapy. Herein, two water-soluble macrocyclic hosts, i. e., a carboxylated leaning tower[6]arene (CLT6) and a carboxylated [2]biphenyl-extended pillar[6]arene (CBpP6), are used to load chemotherapy drug oxaliplatin (OxPt) by forming inclusion complexes (OxPt⊂CLT6 and OxPt⊂CBpP6) through host-guest interactions. Interestingly, OxPt can be released from the macrocyclic cavities of these drug delivery systems (DDSs) via the competitive binding effect of spermine (SPM) because of the stronger binding abilities of CLT6/CBpP6 toward SPM as compared with OxPt, leading to enhanced cytotoxicity on SPM-overexpressed cancer cells, such as breast cancer MCF-7 cells. Moreover, compared to free OxPt, due to the low concentration of SPM in normal cells, OxPt⊂CLT6 and OxPt⊂CBpP6 demonstrated a decreased cytotoxicity on liver L02 cells, which is beneficial for reducing the side effect of anticancer drug during chemotherapy. Such a strategy might be extended to other antitumor drugs and water-soluble macrocycles with suitable cavity sizes to achieve controllable drug delivery and enhanced anticancer ability in supramolecular chemotherapy.
Smart strategies that can decrease the side effect and enhance the therapeutic efficacy of chemotherapy are in urgent need to meet the special demands of cancer therapy. Herein, two water-soluble macrocyclic hosts, i. e., a carboxylated leaning tower[6]arene (CLT6) and a carboxylated [2]biphenyl-extended pillar[6]arene (CBpP6), are used to load chemotherapy drug oxaliplatin (OxPt) by forming inclusion complexes (OxPt⊂CLT6 and OxPt⊂CBpP6) through host-guest interactions. Interestingly, OxPt can be released from the macrocyclic cavities of these drug delivery systems (DDSs) via the competitive binding effect of spermine (SPM) because of the stronger binding abilities of CLT6/CBpP6 toward SPM as compared with OxPt, leading to enhanced cytotoxicity on SPM-overexpressed cancer cells, such as breast cancer MCF-7 cells. Moreover, compared to free OxPt, due to the low concentration of SPM in normal cells, OxPt⊂CLT6 and OxPt⊂CBpP6 demonstrated a decreased cytotoxicity on liver L02 cells, which is beneficial for reducing the side effect of anticancer drug during chemotherapy. Such a strategy might be extended to other antitumor drugs and water-soluble macrocycles with suitable cavity sizes to achieve controllable drug delivery and enhanced anticancer ability in supramolecular chemotherapy.
2021, 32(2): 735-739
doi: 10.1016/j.cclet.2020.07.028
Abstract:
The design and synthesis of a phenoxazine-based metal-organic tetrahedron (Zn4L4) as biomimetic lectin for selectively recognition of glucosamine (GlcN) was reported. Different from the free phenoxazine-based ligand (L), Zn4L4 displayed the highest fluorescent intensity enhancement efficiency toward GlcN over other related natural mono- and disaccharides. Fluorescence titration demonstrated a 1:1 stoichiometric host-guest complex was formed with an association constant about 4.03×104 L/mol. 1H NMR spectroscopic studies confirmed this selectivity resulted from the multiple hydrogen bonding interactions formed between GlcN and Zn4L4. The present results suggested that rational arrangement of recognition sites in the confined space of metal-organic cage is crucial for the selectivity toward target guests.
The design and synthesis of a phenoxazine-based metal-organic tetrahedron (Zn4L4) as biomimetic lectin for selectively recognition of glucosamine (GlcN) was reported. Different from the free phenoxazine-based ligand (L), Zn4L4 displayed the highest fluorescent intensity enhancement efficiency toward GlcN over other related natural mono- and disaccharides. Fluorescence titration demonstrated a 1:1 stoichiometric host-guest complex was formed with an association constant about 4.03×104 L/mol. 1H NMR spectroscopic studies confirmed this selectivity resulted from the multiple hydrogen bonding interactions formed between GlcN and Zn4L4. The present results suggested that rational arrangement of recognition sites in the confined space of metal-organic cage is crucial for the selectivity toward target guests.
2021, 32(2): 740-744
doi: 10.1016/j.cclet.2020.07.041
Abstract:
Three new emitters, namely 10, 10'-(quinoline-2, 8-diyl)bis(10H-phenoxazine) (Fene), 10, 10'-(quinoline-2, 8-diyl)bis(10H-phenothiazine) (Fens) and 10, 10'-(quinoline-2, 8-diyl)bis(9, 9-dimethyl-9, 10-dihydroacridine) (Yad), featuring quinoline as a new electron acceptor have been designed and conveniently synthesized. These emitters possessed small singlet–triplet splitting energy (ΔEst) and twisted structures, which not only endowed them show thermally activated delayed fluorescence (TADF) properties but also afforded a remarkable aggregation-induced emission (AIE) feature. Moreover, they also showed aggregation-induced delayed fluorescence (AIDF) property and good photoluminescence (PL) property, which are the ideal emitters for non-doped organic light-emitting diodes (OLEDs). Furthermore, high-performance non-doped OLEDs based on Fene, Fens and Yad were achieved, and excellent maximum external quantum efficiencies (EQEmax) of 14.9%, 13.1% and 17.4%, respectively, were obtained. It was also found that all devices exhibited relatively low turn-on voltages ranging from 3.0 V to 3.2 V probably due to their twisted conformation and the AIDF properties. These results demonstrated the quinoline-based emitters could have a promising application in non-doped OLEDs.
Three new emitters, namely 10, 10'-(quinoline-2, 8-diyl)bis(10H-phenoxazine) (Fene), 10, 10'-(quinoline-2, 8-diyl)bis(10H-phenothiazine) (Fens) and 10, 10'-(quinoline-2, 8-diyl)bis(9, 9-dimethyl-9, 10-dihydroacridine) (Yad), featuring quinoline as a new electron acceptor have been designed and conveniently synthesized. These emitters possessed small singlet–triplet splitting energy (ΔEst) and twisted structures, which not only endowed them show thermally activated delayed fluorescence (TADF) properties but also afforded a remarkable aggregation-induced emission (AIE) feature. Moreover, they also showed aggregation-induced delayed fluorescence (AIDF) property and good photoluminescence (PL) property, which are the ideal emitters for non-doped organic light-emitting diodes (OLEDs). Furthermore, high-performance non-doped OLEDs based on Fene, Fens and Yad were achieved, and excellent maximum external quantum efficiencies (EQEmax) of 14.9%, 13.1% and 17.4%, respectively, were obtained. It was also found that all devices exhibited relatively low turn-on voltages ranging from 3.0 V to 3.2 V probably due to their twisted conformation and the AIDF properties. These results demonstrated the quinoline-based emitters could have a promising application in non-doped OLEDs.
2021, 32(2): 745-749
doi: 10.1016/j.cclet.2020.05.002
Abstract:
Metal-free heteroatoms dual-doped carbon has been recognized as one of the most promising Pt/C-substitutes for oxygen reduction reaction (ORR). Herein, we optimize the preparation process by doping order of metal-free heteroatoms to obtain the best electrocatalytic performance through three types of dual-doped carbon, including XC-N (first X doping then N doping), NC-X (first N doping then X doping) and NXC (N and X doping) (X = P, S and F). XC-N has more defect than the other two indicated by Raman spectra. X-ray photoelectron spectrom (XPS) measurements indicate that N and X have been dual-doped into the carbon matrix with different doping contents and modes. Electrocatalytic results, including the potential of ORR peak (Ep), the half-wave potential, the diffusion-limiting current density mainly follows the order of XC-N > NC-X > NXC. Furthermore, the synergistic effect of second atom doping are also compared with the single doped carbon (NC, PC, SC and FC). The differences in electronegativity and atomic radius of these metal-free heteroatoms can affect the defect degree, the doping content and mode of heteroatoms on carbon matrix, induce polarization effect and space effect to affect O2 adsorption and product desorption, ultimately to the ORR electrocatalytic performance.
Metal-free heteroatoms dual-doped carbon has been recognized as one of the most promising Pt/C-substitutes for oxygen reduction reaction (ORR). Herein, we optimize the preparation process by doping order of metal-free heteroatoms to obtain the best electrocatalytic performance through three types of dual-doped carbon, including XC-N (first X doping then N doping), NC-X (first N doping then X doping) and NXC (N and X doping) (X = P, S and F). XC-N has more defect than the other two indicated by Raman spectra. X-ray photoelectron spectrom (XPS) measurements indicate that N and X have been dual-doped into the carbon matrix with different doping contents and modes. Electrocatalytic results, including the potential of ORR peak (Ep), the half-wave potential, the diffusion-limiting current density mainly follows the order of XC-N > NC-X > NXC. Furthermore, the synergistic effect of second atom doping are also compared with the single doped carbon (NC, PC, SC and FC). The differences in electronegativity and atomic radius of these metal-free heteroatoms can affect the defect degree, the doping content and mode of heteroatoms on carbon matrix, induce polarization effect and space effect to affect O2 adsorption and product desorption, ultimately to the ORR electrocatalytic performance.
2021, 32(2): 750-754
doi: 10.1016/j.cclet.2020.05.013
Abstract:
Light utilization is one of the key factors for the improvement of photocatalytic performance. Herein, we design C-TiO2 hollow nanoshells with strong Mie resonance for enhanced photocatalytic hydrogen evolution in a dye-sensitized system under visible light irradiation (λ≥420 nm). By tuning the inner diameters of hollow nanoshells, the Mie resonance in hollow nanoshells is adjusted for better excitation of dye molecules, which thus greatly enhances the light utilization in visible light region. This work shows the potential of Mie resonance in nanoshells can be an alternative strategy to increase the light utilization for photocatalysis.
Light utilization is one of the key factors for the improvement of photocatalytic performance. Herein, we design C-TiO2 hollow nanoshells with strong Mie resonance for enhanced photocatalytic hydrogen evolution in a dye-sensitized system under visible light irradiation (λ≥420 nm). By tuning the inner diameters of hollow nanoshells, the Mie resonance in hollow nanoshells is adjusted for better excitation of dye molecules, which thus greatly enhances the light utilization in visible light region. This work shows the potential of Mie resonance in nanoshells can be an alternative strategy to increase the light utilization for photocatalysis.
2021, 32(2): 755-760
doi: 10.1016/j.cclet.2020.05.012
Abstract:
Transition-metal chalcogenides with hollow nanostructure, especially cobalt sulfides, are considered as the most promising non-precious metal catalysts for oxygen evolution reaction. However, it is difficult to synthesize oxygen-containing cobalt sulphides with hollow structure due to the different physical/chemical properties between metal sulfides and metal cobalts. Herein, we report a novel oxygen-containing amorphous cobalt sulfide ball-in-ball hollow spheres (Co-S-O BBHS) synthesized by an anion exchange method. Taking advantage of the ball-in-ball hollow structure, the amorphous Co-S-O BBHS shows superior oxygen evolution reaction (OER) electrocatalytic performance with a low overpotential of 285 mV at 10 mA/cm2, small Tafel slope of 49.67 mV/dec, high Faraday efficiency of 96%, and satisfied durability. Experiments and DFT calculations demonstrate that the introduction of oxygen and sulfur modulates the electronic structure of Co-S-O BBHS, thus enhancing the adsorption of *O (adsorbed O species on catalyst surface) intermediate, which greatly boosts the catalytic activity towards OER. This work provides a new strategy for controllable synthesis of complex hollow structures of transition-metal chalcogenides for OER.
Transition-metal chalcogenides with hollow nanostructure, especially cobalt sulfides, are considered as the most promising non-precious metal catalysts for oxygen evolution reaction. However, it is difficult to synthesize oxygen-containing cobalt sulphides with hollow structure due to the different physical/chemical properties between metal sulfides and metal cobalts. Herein, we report a novel oxygen-containing amorphous cobalt sulfide ball-in-ball hollow spheres (Co-S-O BBHS) synthesized by an anion exchange method. Taking advantage of the ball-in-ball hollow structure, the amorphous Co-S-O BBHS shows superior oxygen evolution reaction (OER) electrocatalytic performance with a low overpotential of 285 mV at 10 mA/cm2, small Tafel slope of 49.67 mV/dec, high Faraday efficiency of 96%, and satisfied durability. Experiments and DFT calculations demonstrate that the introduction of oxygen and sulfur modulates the electronic structure of Co-S-O BBHS, thus enhancing the adsorption of *O (adsorbed O species on catalyst surface) intermediate, which greatly boosts the catalytic activity towards OER. This work provides a new strategy for controllable synthesis of complex hollow structures of transition-metal chalcogenides for OER.
2021, 32(2): 761-764
doi: 10.1016/j.cclet.2020.05.023
Abstract:
CeO2 morphology was proposed to be a crucial factor for reducing nitrobenzene to azoxybenzene under the base-free condition. Herein, the structure-activity relationship of CeO2 catalysts was explored to improve the azoxybenzene yield. A series of CeO2 catalysts were synthesized with seven morphologies to obtain different Ce3+ proportion and various surface areas. Notably, the catalytic performance of these samples for reducing nitrobenzene to azoxybenzene enhanced with the increasing Ce3+ proportion. With the highest surface Ce3+ proportion, the Rod-CeO2 catalyst exhibited 100% conversion of nitrobenzene and 89.8% azoxybenzene selectivity in 7 h at 150 ℃ under 1 MPa CO. Moreover, the preliminary mechanistic analysis indicated that the inhabitation of azoxybenzene to by-product azobenzene resulted in the high selectivity of azoxybenzene.
CeO2 morphology was proposed to be a crucial factor for reducing nitrobenzene to azoxybenzene under the base-free condition. Herein, the structure-activity relationship of CeO2 catalysts was explored to improve the azoxybenzene yield. A series of CeO2 catalysts were synthesized with seven morphologies to obtain different Ce3+ proportion and various surface areas. Notably, the catalytic performance of these samples for reducing nitrobenzene to azoxybenzene enhanced with the increasing Ce3+ proportion. With the highest surface Ce3+ proportion, the Rod-CeO2 catalyst exhibited 100% conversion of nitrobenzene and 89.8% azoxybenzene selectivity in 7 h at 150 ℃ under 1 MPa CO. Moreover, the preliminary mechanistic analysis indicated that the inhabitation of azoxybenzene to by-product azobenzene resulted in the high selectivity of azoxybenzene.
2021, 32(2): 765-769
doi: 10.1016/j.cclet.2020.05.030
Abstract:
The Platinum (Pt)-based catalysts exhibit excellent catalytic performance for the hydrogen evolution reaction (HER) while suffering from poor stability due to the weak interaction between the carbon support and Pt. Herein, a molybdenum-doped titanium dioxide (Ti0.9Mo0.1O2) supported low-Pt electrocatalyst with stronger interaction between catalyst and support is applied to tune the electrocatalytic performance of Pt. The Ti0.9Mo0.1O2 support can not only tolerate the corrosion environment in the catalytic system, but also generate strong metal-support interaction (SMSI) between the oxide and catalyst. A facile solvothermal method is used to prepare Ti0.9Mo0.1O2 as support to anchor Pt nanoparticles. The 5% Pt supported on Ti0.9Mo0.1O2 catalyst exhibits 4.4-fold mass activity (MA) at an overpotential of 50 mV and higher stability than 20% Pt/C with only 1/4 Pt loading. The SMSI between the Ti0.9Mo0.1O2 and Pt prevents the Pt aggregation to achieve excellent stability, and hydrogen spillover effect in the interface between Pt and support benefits the hydrogen production process. This work presents a novel sight for the fabrication and design of oxide supported catalysts in various catalytic system by reasonably employing support effect.
The Platinum (Pt)-based catalysts exhibit excellent catalytic performance for the hydrogen evolution reaction (HER) while suffering from poor stability due to the weak interaction between the carbon support and Pt. Herein, a molybdenum-doped titanium dioxide (Ti0.9Mo0.1O2) supported low-Pt electrocatalyst with stronger interaction between catalyst and support is applied to tune the electrocatalytic performance of Pt. The Ti0.9Mo0.1O2 support can not only tolerate the corrosion environment in the catalytic system, but also generate strong metal-support interaction (SMSI) between the oxide and catalyst. A facile solvothermal method is used to prepare Ti0.9Mo0.1O2 as support to anchor Pt nanoparticles. The 5% Pt supported on Ti0.9Mo0.1O2 catalyst exhibits 4.4-fold mass activity (MA) at an overpotential of 50 mV and higher stability than 20% Pt/C with only 1/4 Pt loading. The SMSI between the Ti0.9Mo0.1O2 and Pt prevents the Pt aggregation to achieve excellent stability, and hydrogen spillover effect in the interface between Pt and support benefits the hydrogen production process. This work presents a novel sight for the fabrication and design of oxide supported catalysts in various catalytic system by reasonably employing support effect.
2021, 32(2): 770-774
doi: 10.1016/j.cclet.2020.05.045
Abstract:
Selective hydrogenation of aromatic amines, especially chemicals such as aniline and bis(4-aminocyclohexyl)methane for non-yellowing polyurethane, is of particular interests due to the extensive applications. To conquer the existing difficulties in selective hydrogenation, the Ru0-Ruδ+/CeO2 catalyst with solid frustrated Lewis pairs was developed for aromatic amines hydrogenation with excellent activity and selectivity under relative milder conditions. The morphology, electronic and chemical properties, especially the Ru0-Ruδ+ clusters and reducible ceria were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), CO2 temperature programmed desorption (CO2-TPD), H2 temperature programmed reduction (H2-TPR), H2 diffuse reflectance Fourier transform infrared spectroscopy (H2-DRIFT), Raman, etc. The 2% Ru/CeO2 catalyst exhibited good conversion of 95% and selectivity greater than 99% toward cyclohexylamine. The volcano curve describing the activity and Ru state was found. Owning to the "acidic site isolation" by surrounding alkaline sites, condensation between the neighboring amine molecules could be effectively suppressed. The catalyst also showed good stability and applicability for other aromatic amines and heteroarenes containing different functional groups.
Selective hydrogenation of aromatic amines, especially chemicals such as aniline and bis(4-aminocyclohexyl)methane for non-yellowing polyurethane, is of particular interests due to the extensive applications. To conquer the existing difficulties in selective hydrogenation, the Ru0-Ruδ+/CeO2 catalyst with solid frustrated Lewis pairs was developed for aromatic amines hydrogenation with excellent activity and selectivity under relative milder conditions. The morphology, electronic and chemical properties, especially the Ru0-Ruδ+ clusters and reducible ceria were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS), CO2 temperature programmed desorption (CO2-TPD), H2 temperature programmed reduction (H2-TPR), H2 diffuse reflectance Fourier transform infrared spectroscopy (H2-DRIFT), Raman, etc. The 2% Ru/CeO2 catalyst exhibited good conversion of 95% and selectivity greater than 99% toward cyclohexylamine. The volcano curve describing the activity and Ru state was found. Owning to the "acidic site isolation" by surrounding alkaline sites, condensation between the neighboring amine molecules could be effectively suppressed. The catalyst also showed good stability and applicability for other aromatic amines and heteroarenes containing different functional groups.
2021, 32(2): 775-778
doi: 10.1016/j.cclet.2020.05.041
Abstract:
Herein, we propose a novel photoelectrochemical (PEC) biosensor for dual microRNAs (miRNAs) highly sensitive and simultaneous biosensing based on strand displaced amplification (SDA) reaction. The recognition of HmiR-21 and Hlet-7a by microRNA-21 and let-7a leads to their change in hairpin structures, subsequently initiating the immobilization of abundant CdS quantum dots (CdS QDs) and methylene blue (MB) based on SDA reaction. The immobilized CdS QDs and MB produce both high PEC currents under 430 nm light and 627 nm light illumination, respectively, and the generated PEC currents are closely relied on target miRNAs amounts. Thus, highly sensitive and simultaneous detection of microRNA-21 Herein, we propose a novel photoelectrochemical (PEC) biosensor for dual microRNAs (miRNAs) highly sensitive and simultaneous biosensing based on strand displaced amplification (SDA) reaction. The recognition of HmiR-21 and Hlet-7a by microRNA-21 and let-7a leads to their change in hairpin structures, subsequently initiating the immobilization of abundant CdS quantum dots (CdS QDs) and methylene blue (MB) based on SDA reaction. The immobilized CdS QDs and MB produce both high PEC currents under 430 nm light and 627 nm light illumination, respectively, and the generated PEC currents are closely relied on target miRNAs amounts. Thus, highly sensitive and simultaneous detection of microRNA-21 and let-7a was readily achieved with detection limit at 6.6 fmol/L and 15.4 fmol/L based on 3σ, respectively. Further, this PEC biosensor was applied in simultaneous analysis of miRNA-21 and let-7a in breast cancer patient's serum with acceptable results. We expect this biosensor will find more useful application in diagnosis of miRNA-related diseases.
Herein, we propose a novel photoelectrochemical (PEC) biosensor for dual microRNAs (miRNAs) highly sensitive and simultaneous biosensing based on strand displaced amplification (SDA) reaction. The recognition of HmiR-21 and Hlet-7a by microRNA-21 and let-7a leads to their change in hairpin structures, subsequently initiating the immobilization of abundant CdS quantum dots (CdS QDs) and methylene blue (MB) based on SDA reaction. The immobilized CdS QDs and MB produce both high PEC currents under 430 nm light and 627 nm light illumination, respectively, and the generated PEC currents are closely relied on target miRNAs amounts. Thus, highly sensitive and simultaneous detection of microRNA-21 Herein, we propose a novel photoelectrochemical (PEC) biosensor for dual microRNAs (miRNAs) highly sensitive and simultaneous biosensing based on strand displaced amplification (SDA) reaction. The recognition of HmiR-21 and Hlet-7a by microRNA-21 and let-7a leads to their change in hairpin structures, subsequently initiating the immobilization of abundant CdS quantum dots (CdS QDs) and methylene blue (MB) based on SDA reaction. The immobilized CdS QDs and MB produce both high PEC currents under 430 nm light and 627 nm light illumination, respectively, and the generated PEC currents are closely relied on target miRNAs amounts. Thus, highly sensitive and simultaneous detection of microRNA-21 and let-7a was readily achieved with detection limit at 6.6 fmol/L and 15.4 fmol/L based on 3σ, respectively. Further, this PEC biosensor was applied in simultaneous analysis of miRNA-21 and let-7a in breast cancer patient's serum with acceptable results. We expect this biosensor will find more useful application in diagnosis of miRNA-related diseases.
2021, 32(2): 779-782
doi: 10.1016/j.cclet.2020.06.009
Abstract:
We presented a low-abundance mutation detection method with lambda exonuclease and DNA three-way junction structure. The assistant strand in the DNA three-way junction structure could regulate the reaction system from the kinetics and thermodynamics aspects. The optimization of the assistant strand helps to improve the selectivity of the mutant-type DNA to the wild-type DNA about 35 times. Moreover, the cost of the optimization process could be saved by about 90%. The method was applied to the detection of a human ovarian cancer-related gene mutation BRCA1 (rs1799949, c.2082C>T). The limit of detection to the mutation abundance in the DNA three-way junction structure system (0.2%) was one order lower compared with that in the double-stranded DNA structure system (2%). The mutation abundance in different standard samples was quantitively measured, and the results were consistent with the initial abundance in the standard samples.
We presented a low-abundance mutation detection method with lambda exonuclease and DNA three-way junction structure. The assistant strand in the DNA three-way junction structure could regulate the reaction system from the kinetics and thermodynamics aspects. The optimization of the assistant strand helps to improve the selectivity of the mutant-type DNA to the wild-type DNA about 35 times. Moreover, the cost of the optimization process could be saved by about 90%. The method was applied to the detection of a human ovarian cancer-related gene mutation BRCA1 (rs1799949, c.2082C>T). The limit of detection to the mutation abundance in the DNA three-way junction structure system (0.2%) was one order lower compared with that in the double-stranded DNA structure system (2%). The mutation abundance in different standard samples was quantitively measured, and the results were consistent with the initial abundance in the standard samples.
2021, 32(2): 783-786
doi: 10.1016/j.cclet.2020.06.030
Abstract:
Circulating tumor DNA (ctDNA) refers to a class of acellular nucleic acids carrying genetic features of primary tumor, which can be regarded as a promising noninvasive biomarker for cancer diagnosis. The development of ctDNA assay is an important component of liquid biopsy. In this study, we have fabricated a novel electrochemical strategy for ultrasensitive detection of ctDNA combining the merits of strand displacement amplification and DNA nanostructures. Stable DNA triangular prism is firstly self-assembled and modified on the electrode surface. After target initiated strand displacement polymerization reaction, the generated DNA product helps the formation of three-way junction nanostructure on triangular prism, which localizes electrochemical species. By carefully investigating the electrochemical responses, the limit of detection (LOD) for ctDNA assay as low as 48 amol/L is achieved. This proposed electrochemical biosensor shows great potential for clinical applications.
Circulating tumor DNA (ctDNA) refers to a class of acellular nucleic acids carrying genetic features of primary tumor, which can be regarded as a promising noninvasive biomarker for cancer diagnosis. The development of ctDNA assay is an important component of liquid biopsy. In this study, we have fabricated a novel electrochemical strategy for ultrasensitive detection of ctDNA combining the merits of strand displacement amplification and DNA nanostructures. Stable DNA triangular prism is firstly self-assembled and modified on the electrode surface. After target initiated strand displacement polymerization reaction, the generated DNA product helps the formation of three-way junction nanostructure on triangular prism, which localizes electrochemical species. By carefully investigating the electrochemical responses, the limit of detection (LOD) for ctDNA assay as low as 48 amol/L is achieved. This proposed electrochemical biosensor shows great potential for clinical applications.
2021, 32(2): 787-790
doi: 10.1016/j.cclet.2020.06.042
Abstract:
Herein, we report a microwave-assisted acid-induced post-treatment method for the formation of linker vacancies within Zr-based metal organic frameworks (Zr-MOFs). The number of linker vacancies can be easily regulated with this method by changing the concentration of the HCl solution and the duration of microwave irradiation. The optimized defective UiO-66 showed higher linker defects with a higher specific surface area and thermal stability. The results of the catalytic cyclization of citronella showed that the Zr-MOFs with more defects exhibited enhanced catalytic performance. This work may provide a new method for the creation of defective MOFs with high activity and stability.
Herein, we report a microwave-assisted acid-induced post-treatment method for the formation of linker vacancies within Zr-based metal organic frameworks (Zr-MOFs). The number of linker vacancies can be easily regulated with this method by changing the concentration of the HCl solution and the duration of microwave irradiation. The optimized defective UiO-66 showed higher linker defects with a higher specific surface area and thermal stability. The results of the catalytic cyclization of citronella showed that the Zr-MOFs with more defects exhibited enhanced catalytic performance. This work may provide a new method for the creation of defective MOFs with high activity and stability.
2021, 32(2): 791-795
doi: 10.1016/j.cclet.2020.07.020
Abstract:
The detection of bacterial pathogen such as Staphylococcus aureus (S. aureus) is essential for the regulation of food hygiene and disease diagnosis. Herein, we developed a simple one-step fluorescence resonance energy transfer (FRET)-based sensor for specific and sensitive detection of S. aureus in food and serum samples, in which aptamer-modified quantum dots (aptamer-QDs) was employed as the energy donor and antibiotic of teicoplanin functionalized-gold nanoparticles (Teico-AuNPs) was chosen as the energy acceptor. Within 1 h, the FRET-based sensor showed a linear range of from 10 cfu/mL to 5×108 cfu/mL, with the low limit of detection (LOD, 2 cfu/mL) for S. aureus in buffer. When further applied to assay S. aureus in real samples, the FRET-based sensor showed good recoveries ranging from 84.5% to 110.0%, with relative standard derivations (RSDs) of 0.01%–0.44% and a LOD of 100 cfu/mL in milk, orange juice and human serum.
The detection of bacterial pathogen such as Staphylococcus aureus (S. aureus) is essential for the regulation of food hygiene and disease diagnosis. Herein, we developed a simple one-step fluorescence resonance energy transfer (FRET)-based sensor for specific and sensitive detection of S. aureus in food and serum samples, in which aptamer-modified quantum dots (aptamer-QDs) was employed as the energy donor and antibiotic of teicoplanin functionalized-gold nanoparticles (Teico-AuNPs) was chosen as the energy acceptor. Within 1 h, the FRET-based sensor showed a linear range of from 10 cfu/mL to 5×108 cfu/mL, with the low limit of detection (LOD, 2 cfu/mL) for S. aureus in buffer. When further applied to assay S. aureus in real samples, the FRET-based sensor showed good recoveries ranging from 84.5% to 110.0%, with relative standard derivations (RSDs) of 0.01%–0.44% and a LOD of 100 cfu/mL in milk, orange juice and human serum.
2021, 32(2): 796-800
doi: 10.1016/j.cclet.2020.07.038
Abstract:
A novel Pd-Fe/α-Al2O3 catalyst was synthesized by incipient-wetness impregnation method with bayberry tannin as chelating promoter and commercial hollow column Raschig ring α-Al2O3 as support for the synthesis of diethyl oxalate from CO and ethyl nitrite. A variety of characterization techniques including N2 physical adsorption, optical microscopy, scanning electron microscopy and energy dispersive system (SEM-EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), were employed to explore the relationship between the physicochemical properties and activity of catalysts. It indicated that a large number of phenolic hydroxyl groups in bayberry tannin can efficiently anchor the active component Pd, reduce the particle size and make the active Pd as a multi-ring distribution on the commercial α-Al2O3 support, which were beneficial to improve the catalytic activity for the production of diethyl oxalate from CO and ethyl nitrite. 0.3 wt% Pd-Fe/α-Al2O3 showed excellent catalytic activity and selectivity in a continuous flow, fixed-bed reactor with the loading amount of 10 mL catalysts. Under the mild reaction conditions, the space-time yield of diethyl oxalate was 978 g L-1 h-1 and CO conversion was 44% with the selectivity to diethyl oxalate of 95.5%.
A novel Pd-Fe/α-Al2O3 catalyst was synthesized by incipient-wetness impregnation method with bayberry tannin as chelating promoter and commercial hollow column Raschig ring α-Al2O3 as support for the synthesis of diethyl oxalate from CO and ethyl nitrite. A variety of characterization techniques including N2 physical adsorption, optical microscopy, scanning electron microscopy and energy dispersive system (SEM-EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), were employed to explore the relationship between the physicochemical properties and activity of catalysts. It indicated that a large number of phenolic hydroxyl groups in bayberry tannin can efficiently anchor the active component Pd, reduce the particle size and make the active Pd as a multi-ring distribution on the commercial α-Al2O3 support, which were beneficial to improve the catalytic activity for the production of diethyl oxalate from CO and ethyl nitrite. 0.3 wt% Pd-Fe/α-Al2O3 showed excellent catalytic activity and selectivity in a continuous flow, fixed-bed reactor with the loading amount of 10 mL catalysts. Under the mild reaction conditions, the space-time yield of diethyl oxalate was 978 g L-1 h-1 and CO conversion was 44% with the selectivity to diethyl oxalate of 95.5%.
2021, 32(2): 801-804
doi: 10.1016/j.cclet.2020.07.022
Abstract:
Research on pollution characteristics and toxicities of emerging polycyclic aromatic sulfur heterocycles (PASHs) in PM2.5 has not been reported due to the lack of analytical method with the needed performance. In the present study, a novel method for the determination of 14 PASHs in PM2.5 was developed using atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS). Atmospheric pressure chemical ionization was operated with multiple reaction monitoring in positive ionization mode. High sensitivity (method detection limit < 1.673 pg/m3), acceptable recoveries (67.6%–120.8%) and precisions (RSD of 2.2%–15.4%) were obtained. The method was successfully applied for analyzing PASHs in 10 PM2.5 samples collected from Taiyuan, a typical industrial city in China, in 2016. The total concentrations were from 929 pg/m3 to 14,593 pg/m3. The determined levels indicated that further investigations on environmental fate and toxicities of PM2.5-bound PASHs may be needed.
Research on pollution characteristics and toxicities of emerging polycyclic aromatic sulfur heterocycles (PASHs) in PM2.5 has not been reported due to the lack of analytical method with the needed performance. In the present study, a novel method for the determination of 14 PASHs in PM2.5 was developed using atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS). Atmospheric pressure chemical ionization was operated with multiple reaction monitoring in positive ionization mode. High sensitivity (method detection limit < 1.673 pg/m3), acceptable recoveries (67.6%–120.8%) and precisions (RSD of 2.2%–15.4%) were obtained. The method was successfully applied for analyzing PASHs in 10 PM2.5 samples collected from Taiyuan, a typical industrial city in China, in 2016. The total concentrations were from 929 pg/m3 to 14,593 pg/m3. The determined levels indicated that further investigations on environmental fate and toxicities of PM2.5-bound PASHs may be needed.
2021, 32(2): 805-810
doi: 10.1016/j.cclet.2020.04.013
Abstract:
Realizing nitrogen reduction reaction (NRR) to synthesis NH3 under mild conditions has gained extensive attention as a promising alternative way to the energy- and emission-intensive Haber–Bosch process. Among varieties of potential strategies, photoelectrochemical (PEC) NRR exhibits many advantages including utilization of solar energy, water (H2O) as the hydrogen source and ambient operation conditions. Herein, we have designed a solar-driven PEC-NRR system integrating high-efficiency Fe2O3-based photoanode and atomically dispersed cobalt (Co) cathode for ambient NH3 synthesis. Using such solar-driven PEC-NRR system, high-efficiency Fe2O3-based photoanode is responsible for H2O/OH- oxidation, and meanwhile the generated photoelectrons transfer to the single-atom Co cathode for the N2 reduction to NH3. As a result, this system can afford an NH3 yield rate of 1021.5 μg mgCo-1 h-1 and a faradic efficiency of 11.9% at an applied potential bias of 1.2 V (versus reversible hydrogen electrode) on photoanode in 0.2 mol/L NaOH electrolyte under simulated sunlight irradiation.
Realizing nitrogen reduction reaction (NRR) to synthesis NH3 under mild conditions has gained extensive attention as a promising alternative way to the energy- and emission-intensive Haber–Bosch process. Among varieties of potential strategies, photoelectrochemical (PEC) NRR exhibits many advantages including utilization of solar energy, water (H2O) as the hydrogen source and ambient operation conditions. Herein, we have designed a solar-driven PEC-NRR system integrating high-efficiency Fe2O3-based photoanode and atomically dispersed cobalt (Co) cathode for ambient NH3 synthesis. Using such solar-driven PEC-NRR system, high-efficiency Fe2O3-based photoanode is responsible for H2O/OH- oxidation, and meanwhile the generated photoelectrons transfer to the single-atom Co cathode for the N2 reduction to NH3. As a result, this system can afford an NH3 yield rate of 1021.5 μg mgCo-1 h-1 and a faradic efficiency of 11.9% at an applied potential bias of 1.2 V (versus reversible hydrogen electrode) on photoanode in 0.2 mol/L NaOH electrolyte under simulated sunlight irradiation.
2021, 32(2): 811-815
doi: 10.1016/j.cclet.2020.04.046
Abstract:
In this study, large-scale Te-doped polycrystalline SnSe nanopowders were synthesized by a facile hydrothermal approach and the effect of Te doping on the thermoelectric properties of SnSe was fully investigated. It is found that the carrier concentration increases due to the reduction of band gap by alloying with Te, which contributes to significant enhancement of electrical conductivity especially at room temperature. Combined with the moderated Seebeck coefficient, a high power factor of 4.59 μW cm−1 K−2 is obtained at 773 K. Furthermore, the lattice thermal conductivity is greatly reduced upon Te substitution owing to the atomic point defect scattering. Benefiting from the synergistically optimized both electrical- and thermal-transport properties by Te-doping, thermoelectric performance of polycrystalline SnSe is enhanced in the whole temperature range with a maximum ZT of ~0.79 at a relatively low temperature (773 K) for SnSe0.85Te0.15. This study provides a low-cost and simple low-temperature method to mass production of SnSe with high thermoelectric performance for practical applications
In this study, large-scale Te-doped polycrystalline SnSe nanopowders were synthesized by a facile hydrothermal approach and the effect of Te doping on the thermoelectric properties of SnSe was fully investigated. It is found that the carrier concentration increases due to the reduction of band gap by alloying with Te, which contributes to significant enhancement of electrical conductivity especially at room temperature. Combined with the moderated Seebeck coefficient, a high power factor of 4.59 μW cm−1 K−2 is obtained at 773 K. Furthermore, the lattice thermal conductivity is greatly reduced upon Te substitution owing to the atomic point defect scattering. Benefiting from the synergistically optimized both electrical- and thermal-transport properties by Te-doping, thermoelectric performance of polycrystalline SnSe is enhanced in the whole temperature range with a maximum ZT of ~0.79 at a relatively low temperature (773 K) for SnSe0.85Te0.15. This study provides a low-cost and simple low-temperature method to mass production of SnSe with high thermoelectric performance for practical applications
2021, 32(2): 816-821
doi: 10.1016/j.cclet.2020.04.040
Abstract:
The development of high-performance and cost-effective electrocatalysts towards oxygen reduction reaction (ORR) is of significant importance, but still challenging for the practical applications in related energy systems. ORR process typically suffers from sluggish kinetics, the exploration of ORR electrocatalyst thus requires elaborate design. Herein, an effective strategy is developed for growing Co/N-doped carbon nanotube arrays on 2D MOFs-derived matrix via the pyrolysis of Co/Zn metal-organic-framework (MOF) nanosheets. The Co/Zn-MOF nanosheets serve as both the self-template for the 2D carbonized framework morphology and C/N source for the in-situ growth of 1D N-doped carbon nanotubes. The constructed hierarchical architecture effectively integrates the 0D/1D Co nanoparticle/N-doped carbon nanotube interface and 1D (nanotubes)/2D (nanosheets) junction into frameworks with highly exposed active surface, enhanced mass-transport kinetics and electrical conductivity. As a result, the designed composite exhibits superior ORR activity and durability in alkaline media as compared to commercial Pt/C. Particularly, it shows promising ORR performance with a half-wave potential of 0.78 V versus reversible hydrogen electrode and negligible activity attenuation after 5000 potential cycles in acidic electrolyte. The designed strategy can be extended to construct other MOFs-derived carbon matrixes with diverse hierarchical structures and provide an efficient avenue for searching high-performance electrocatalysts.
The development of high-performance and cost-effective electrocatalysts towards oxygen reduction reaction (ORR) is of significant importance, but still challenging for the practical applications in related energy systems. ORR process typically suffers from sluggish kinetics, the exploration of ORR electrocatalyst thus requires elaborate design. Herein, an effective strategy is developed for growing Co/N-doped carbon nanotube arrays on 2D MOFs-derived matrix via the pyrolysis of Co/Zn metal-organic-framework (MOF) nanosheets. The Co/Zn-MOF nanosheets serve as both the self-template for the 2D carbonized framework morphology and C/N source for the in-situ growth of 1D N-doped carbon nanotubes. The constructed hierarchical architecture effectively integrates the 0D/1D Co nanoparticle/N-doped carbon nanotube interface and 1D (nanotubes)/2D (nanosheets) junction into frameworks with highly exposed active surface, enhanced mass-transport kinetics and electrical conductivity. As a result, the designed composite exhibits superior ORR activity and durability in alkaline media as compared to commercial Pt/C. Particularly, it shows promising ORR performance with a half-wave potential of 0.78 V versus reversible hydrogen electrode and negligible activity attenuation after 5000 potential cycles in acidic electrolyte. The designed strategy can be extended to construct other MOFs-derived carbon matrixes with diverse hierarchical structures and provide an efficient avenue for searching high-performance electrocatalysts.
2021, 32(2): 822-825
doi: 10.1016/j.cclet.2020.04.047
Abstract:
Controlling ions transport across the membrane at different pH environments is essential for the physiological process and artificial systems. Many efforts have been devoted to pH-responsive ion gating, while rarely systems can maintain the rectification in pH-changing environments. Here, a composite nanochannel system is fabricated, which shows unidirectional rectification with high performance in a wide pH range. In the system, block copolymer (BCP) and polyethylene terephthalate (PET) are employed for the amphoteric nanochannels fabrication. Based on the composite system, a model is built for the theoretical simulation. Thereafter, rectification mapping is conducted on the system, which can provide abundant information about the relations between charge distribution and ions transport properties. The proposed rectification mapping can definitely help to design new materials with special ion transport properties, such as high-performance membranes used in the salinity gradient power generation field.
Controlling ions transport across the membrane at different pH environments is essential for the physiological process and artificial systems. Many efforts have been devoted to pH-responsive ion gating, while rarely systems can maintain the rectification in pH-changing environments. Here, a composite nanochannel system is fabricated, which shows unidirectional rectification with high performance in a wide pH range. In the system, block copolymer (BCP) and polyethylene terephthalate (PET) are employed for the amphoteric nanochannels fabrication. Based on the composite system, a model is built for the theoretical simulation. Thereafter, rectification mapping is conducted on the system, which can provide abundant information about the relations between charge distribution and ions transport properties. The proposed rectification mapping can definitely help to design new materials with special ion transport properties, such as high-performance membranes used in the salinity gradient power generation field.
2021, 32(2): 826-829
doi: 10.1016/j.cclet.2020.04.054
Abstract:
Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances. Herein, a new type of flexible Na3(VOPO4)2F cathode with nanocubes tightly assembled on carbon cloth is fabricated by a facile solvothermal method for the first time. The cathode is able to exhibit superior rate capability and stable cycling performance up to 1000 cycles, due to the surface-assembling of crystalline nanocubes on carbon fibers. In addition, it shows good mechanical flexibility, nearly no capacity decay is observed after continuous bending of 500 times. With this novel cathode and a directly-grown Na2Ti2O5 anode, a fully binder-free Na-ion battery is assembled. It can deliver a high working voltage and increased gravimetric energy/power densities (maximum values: 220.2 Wh/kg; 5674.7 W/kg), and can power a LED indicator at bending angles from 0° to 180°.
Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances. Herein, a new type of flexible Na3(VOPO4)2F cathode with nanocubes tightly assembled on carbon cloth is fabricated by a facile solvothermal method for the first time. The cathode is able to exhibit superior rate capability and stable cycling performance up to 1000 cycles, due to the surface-assembling of crystalline nanocubes on carbon fibers. In addition, it shows good mechanical flexibility, nearly no capacity decay is observed after continuous bending of 500 times. With this novel cathode and a directly-grown Na2Ti2O5 anode, a fully binder-free Na-ion battery is assembled. It can deliver a high working voltage and increased gravimetric energy/power densities (maximum values: 220.2 Wh/kg; 5674.7 W/kg), and can power a LED indicator at bending angles from 0° to 180°.
2021, 32(2): 830-833
doi: 10.1016/j.cclet.2020.04.058
Abstract:
Electrical double-layer capacitors are widely concerned for their high power density, long cycling life and high cycling efficiency. However, their wide application is limited by their low energy density. In this study, we propose a simple yet environmental friendly method to synthesize cobalt and nitrogen atoms co-doped porous carbon (CoAT-NC) material. Cobalt atoms connected with primarily pyridinic nitrogen atoms can be uniformly dispersed in the amorphous carbon matrix, which is benefit for improving electrical conductivity and density of states of the carbon material. Therefore, an enhanced performance is expected when CoAT-NC is served as electrode in a supercapacitor device. CoAT-NC displays a good gravimetric capacitance of 160 F/g at 0.5 A/g combing with outstanding capacitance retention of 90% at an extremely high current density of 100 A/g in acid electrolyte. Furthermore, a good energy density of 30 Wh/kg can be obtained in the organic electrolyte.
Electrical double-layer capacitors are widely concerned for their high power density, long cycling life and high cycling efficiency. However, their wide application is limited by their low energy density. In this study, we propose a simple yet environmental friendly method to synthesize cobalt and nitrogen atoms co-doped porous carbon (CoAT-NC) material. Cobalt atoms connected with primarily pyridinic nitrogen atoms can be uniformly dispersed in the amorphous carbon matrix, which is benefit for improving electrical conductivity and density of states of the carbon material. Therefore, an enhanced performance is expected when CoAT-NC is served as electrode in a supercapacitor device. CoAT-NC displays a good gravimetric capacitance of 160 F/g at 0.5 A/g combing with outstanding capacitance retention of 90% at an extremely high current density of 100 A/g in acid electrolyte. Furthermore, a good energy density of 30 Wh/kg can be obtained in the organic electrolyte.
2021, 32(2): 834-837
doi: 10.1016/j.cclet.2020.05.008
Abstract:
Hydrous electrolytes with high electrochemical potentials were obtained by hydrating water molecules into solutes to form high Li: water molar ratio electrolytes (HMRE). Solid polyethylene glycol (PEG) were employed to enhance the molar ratio of Li+ to water in the electrolytes while reducing the consumption of Li-salt. The obtained mole ratio of Li+ to water molecules in the hydrous electrolytes was greater than 1:1; however, the mass fraction of Li-salt was reduced to 61% (approximately 5.5 mol/kg, based on water and PEG). Compared with that of water-in-salt electrolytes, the mass fraction of Li-salt could be remarkably reduced by adding solid PEG. The electrochemical stability of the electrolytes improved considerably because of the strong hydration of Li+ by the water molecules. A beneficial passivation effect, arising from the decomposition of the electrolyte, at a wide potential window was observed.
Hydrous electrolytes with high electrochemical potentials were obtained by hydrating water molecules into solutes to form high Li: water molar ratio electrolytes (HMRE). Solid polyethylene glycol (PEG) were employed to enhance the molar ratio of Li+ to water in the electrolytes while reducing the consumption of Li-salt. The obtained mole ratio of Li+ to water molecules in the hydrous electrolytes was greater than 1:1; however, the mass fraction of Li-salt was reduced to 61% (approximately 5.5 mol/kg, based on water and PEG). Compared with that of water-in-salt electrolytes, the mass fraction of Li-salt could be remarkably reduced by adding solid PEG. The electrochemical stability of the electrolytes improved considerably because of the strong hydration of Li+ by the water molecules. A beneficial passivation effect, arising from the decomposition of the electrolyte, at a wide potential window was observed.
2021, 32(2): 838-841
doi: 10.1016/j.cclet.2020.05.018
Abstract:
A new family of isostructural 3d-4f polymetallic complexes, formulated as [Cu6Ln5(μ3−OH)9 (C4H8O2N)6(C5H4ON)6(H2O)9]·(ClO4)6·(H2O)22 (Ln = Pr, 1; Nd, 2; Sm, 3; Eu, 4; Gd, 5), was successfully isolated through the simple hydrolysis reaction of 2-aminoisobutyric acid, 2-hydroxypyridine, Cu(CH3COO)2·H2O, and Ln(ClO4)3·6H2O. Notably, the [Cu6Ln5] clusters with high molecular symmetry of D3h are rare examples of 2-aminoisobutyric acid-based 3d-4f clusters. The successful theoretical modeling of 5 yielded that the Gd-Gd exchange is of order 0.2 K, whereas the Gd-Cu exchange is an order of magnitude larger. Magnetization data collected for complex 5 yield a magnetic entropy change (−ΔSm) of 19.6 J kg−1 K−1 at 3 K and 7 T, which may be attributed to the weak magnetic interactions between the component metal ions.
A new family of isostructural 3d-4f polymetallic complexes, formulated as [Cu6Ln5(μ3−OH)9 (C4H8O2N)6(C5H4ON)6(H2O)9]·(ClO4)6·(H2O)22 (Ln = Pr, 1; Nd, 2; Sm, 3; Eu, 4; Gd, 5), was successfully isolated through the simple hydrolysis reaction of 2-aminoisobutyric acid, 2-hydroxypyridine, Cu(CH3COO)2·H2O, and Ln(ClO4)3·6H2O. Notably, the [Cu6Ln5] clusters with high molecular symmetry of D3h are rare examples of 2-aminoisobutyric acid-based 3d-4f clusters. The successful theoretical modeling of 5 yielded that the Gd-Gd exchange is of order 0.2 K, whereas the Gd-Cu exchange is an order of magnitude larger. Magnetization data collected for complex 5 yield a magnetic entropy change (−ΔSm) of 19.6 J kg−1 K−1 at 3 K and 7 T, which may be attributed to the weak magnetic interactions between the component metal ions.
2021, 32(2): 842-848
doi: 10.1016/j.cclet.2020.05.021
Abstract:
Plant polyphenol-based coordination polymers (CPs) with ultra-small particle size and tailorable compositions are highly desired in biomedical applications, but their synthesis is still challenging due to the sophisticated coordination assembly process and unavoidable self-oxidation polymerization of polyphenol. Herein, a general ligand covalent-modification mediated coordination assembly strategy is proposed for the synthesis of water-dispersible CPs with tunable metal species (e.g., Gd, Cu, Ni, Zn, Fe) and ultra-small diameter (8.6–37.8 nm) using nontoxic plant polyphenol (e.g., tannic acid, gallic acid) as a polymerizable ligand. Polyphenol molecules react with formaldehyde firstly, which can effectively retard the oxidation induced self-polymerization of polyphenol and lead to the formation of metal ions containing CPs colloidal nanoparticles. These ultrafine nanoparticles with stably chelated metal ions are highly water dispersible and thus advantageous for bioimaging. As an example, ultra-small Gd contained CPs exhibit higher longitudinal relaxivity (r1 = 25.5 L mmol-1 s-1) value with low r2/r1 (1.19) than clinically used Magnevist (Gd-DTPA, r1 = 3.7 L mmol-1 s-1). Due to the enhanced permeability and retention effect, they can be further used as a positive contrast agent for T1-weighted MR imaging of tumour.
Plant polyphenol-based coordination polymers (CPs) with ultra-small particle size and tailorable compositions are highly desired in biomedical applications, but their synthesis is still challenging due to the sophisticated coordination assembly process and unavoidable self-oxidation polymerization of polyphenol. Herein, a general ligand covalent-modification mediated coordination assembly strategy is proposed for the synthesis of water-dispersible CPs with tunable metal species (e.g., Gd, Cu, Ni, Zn, Fe) and ultra-small diameter (8.6–37.8 nm) using nontoxic plant polyphenol (e.g., tannic acid, gallic acid) as a polymerizable ligand. Polyphenol molecules react with formaldehyde firstly, which can effectively retard the oxidation induced self-polymerization of polyphenol and lead to the formation of metal ions containing CPs colloidal nanoparticles. These ultrafine nanoparticles with stably chelated metal ions are highly water dispersible and thus advantageous for bioimaging. As an example, ultra-small Gd contained CPs exhibit higher longitudinal relaxivity (r1 = 25.5 L mmol-1 s-1) value with low r2/r1 (1.19) than clinically used Magnevist (Gd-DTPA, r1 = 3.7 L mmol-1 s-1). Due to the enhanced permeability and retention effect, they can be further used as a positive contrast agent for T1-weighted MR imaging of tumour.
2021, 32(2): 849-853
doi: 10.1016/j.cclet.2020.05.025
Abstract:
The P2-type manganese-based Na0.7MnO2 cathode materials attract great interest due to their high theoretical capacity. However, these materials suffer from rapid capacity fading, poor rate performance and severe voltage decay resulting from phase transition and sluggish reaction kinetics. In this work we report a novel Nb-doped Na0.7[Ni0.3Co0.1Mn0.6]1-xNbxO2 with significantly suppressed voltage decay and enhanced cycling stability. The strong Nb-O bond can efficiently stabilize the TMO framework, and the as prepared material demonstrates much lower discharge midpoint voltage decay (0.132 V) than that of pristine one (0.319 V) after 200 cycles. Consequently, a remarkably improved cycling performance with a capacity retention of 87.9% after 200 cycle at 0.5 C is achieved, showing a 2.4 fold improvement as compared to the control sample Na0.7Ni0.3Co0.1Mn0.6O2 (~37% rotation). Even at 2 C, a capacity retention of 68.4% is retained after 500 cycles. Remarkably, the as prepared material can be applied at low temperature of −20 ℃, showing a capacity retention of 81% as compared to that at room temperature.
The P2-type manganese-based Na0.7MnO2 cathode materials attract great interest due to their high theoretical capacity. However, these materials suffer from rapid capacity fading, poor rate performance and severe voltage decay resulting from phase transition and sluggish reaction kinetics. In this work we report a novel Nb-doped Na0.7[Ni0.3Co0.1Mn0.6]1-xNbxO2 with significantly suppressed voltage decay and enhanced cycling stability. The strong Nb-O bond can efficiently stabilize the TMO framework, and the as prepared material demonstrates much lower discharge midpoint voltage decay (0.132 V) than that of pristine one (0.319 V) after 200 cycles. Consequently, a remarkably improved cycling performance with a capacity retention of 87.9% after 200 cycle at 0.5 C is achieved, showing a 2.4 fold improvement as compared to the control sample Na0.7Ni0.3Co0.1Mn0.6O2 (~37% rotation). Even at 2 C, a capacity retention of 68.4% is retained after 500 cycles. Remarkably, the as prepared material can be applied at low temperature of −20 ℃, showing a capacity retention of 81% as compared to that at room temperature.
2021, 32(2): 854-860
doi: 10.1016/j.cclet.2020.05.029
Abstract:
The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO) n- (n = 5–8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy. During the consecutive CO adsorption, the μ2-O-bent structure initially is the most favorable for TaNiO(CO)5-, and subsequently both μ2-O-bent and μ2-O-linear structures are degenerate for TaNiO(CO)6-, then the μ2-O-linear structure is most preferential for TaNiO(CO)7-, and finally the η2-CO2-tagged structure is the most energetically competitive one for TaNiO(CO)8-, i.e., the CO oxidation occurs at n = 8. In contrast to the literature reported CO oxidation on heteronuclear metal oxide complexes generally proceeding via Langmuir–Hinshelwood-like mechanism, complementary theoretical calculations suggest that both Langmuir–Hinshelwood-like and Eley–Rideal-like mechanisms prevail for the CO oxidation reaction on TaNiO(CO)8- complex. Our findings provide new insight into the composition-selective mechanism of CO oxidation on heteronuclear metal complexes, of which the composition be tailored to fulfill the desired chemical behaviors.
The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO) n- (n = 5–8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy. During the consecutive CO adsorption, the μ2-O-bent structure initially is the most favorable for TaNiO(CO)5-, and subsequently both μ2-O-bent and μ2-O-linear structures are degenerate for TaNiO(CO)6-, then the μ2-O-linear structure is most preferential for TaNiO(CO)7-, and finally the η2-CO2-tagged structure is the most energetically competitive one for TaNiO(CO)8-, i.e., the CO oxidation occurs at n = 8. In contrast to the literature reported CO oxidation on heteronuclear metal oxide complexes generally proceeding via Langmuir–Hinshelwood-like mechanism, complementary theoretical calculations suggest that both Langmuir–Hinshelwood-like and Eley–Rideal-like mechanisms prevail for the CO oxidation reaction on TaNiO(CO)8- complex. Our findings provide new insight into the composition-selective mechanism of CO oxidation on heteronuclear metal complexes, of which the composition be tailored to fulfill the desired chemical behaviors.
2021, 32(2): 861-865
doi: 10.1016/j.cclet.2020.05.037
Abstract:
Long-emission carbon dots (CDs) is triggering immense enthusiasm on account of their intrinsic merits of high chemical stability and excellent optical properties. In this study, a facile and rapid approach was developed for the preparation of barium-doped carbon dots (Ba-CDs) with yellow fluorescence emission and high quantum yields. Surface chemistry and the chemical architecture of the Ba-CDs was revealed under various spectroscopic methods. This work provides more insights into the effects of charge transfer caused by Ba heteroatoms, which is considered as the most challenging step in the investigation on luminescence mechanism. Remarkably, the prepared Ba-CDs were successfully applied as fluorescent probes in the detection of trace water in organic solvents (ethanol, isopropanol, acetone, tetrahydrofuran). Comparing with traditional fluorescent probes for water detection in organic solvents, Ba-CDs detection provides a more sensitive, much faster and more economical approach.
Long-emission carbon dots (CDs) is triggering immense enthusiasm on account of their intrinsic merits of high chemical stability and excellent optical properties. In this study, a facile and rapid approach was developed for the preparation of barium-doped carbon dots (Ba-CDs) with yellow fluorescence emission and high quantum yields. Surface chemistry and the chemical architecture of the Ba-CDs was revealed under various spectroscopic methods. This work provides more insights into the effects of charge transfer caused by Ba heteroatoms, which is considered as the most challenging step in the investigation on luminescence mechanism. Remarkably, the prepared Ba-CDs were successfully applied as fluorescent probes in the detection of trace water in organic solvents (ethanol, isopropanol, acetone, tetrahydrofuran). Comparing with traditional fluorescent probes for water detection in organic solvents, Ba-CDs detection provides a more sensitive, much faster and more economical approach.
2021, 32(2): 866-869
doi: 10.1016/j.cclet.2020.06.004
Abstract:
The design of pore structure is the key factor for the performance of porous carbon spheres. In this work, novel micron-sized colloidal crystal microspheres consisting of fibrous silica (F-SiO2) nanoparticles are firstly prepared by water-evaporation-induced self-assembly of F-SiO2 nanoparticles in the droplets of an inverse emulsion system to be used as sacrificial templates. Acrylonitrile (AN) was infiltrated in the voids of the F-SiO2 colloidal crystal microspheres, and in-situ induced by 60Co γ-ray to polymerize into polyacrylonitrile (PAN). After the PAN-infiltrated F-SiO2 colloidal crystal microspheres were carbonized and etched with HF solution, novel micron-sized inverse-opal N-doped carbon (IO-NC) microspheres consisting of hollow carbon nanoparticles with a hierarchical macro/meso-porous inner surface were obtained. The IO-NC microspheres have a specific surface area as high as 266.4 m2/g and a molar ratio of C/N of 5. They have a good dispersibility in water, and show a high adsorption capacity towards rhodamine B (RhB) up to 137.28 mg/(g microsphere). This work offers a way to obtain novel micron-sized hierarchical macro/meso-porous N-doped carbon microspheres, which opens a new idea to prepare high-performance hierarchical porous carbon materials.
The design of pore structure is the key factor for the performance of porous carbon spheres. In this work, novel micron-sized colloidal crystal microspheres consisting of fibrous silica (F-SiO2) nanoparticles are firstly prepared by water-evaporation-induced self-assembly of F-SiO2 nanoparticles in the droplets of an inverse emulsion system to be used as sacrificial templates. Acrylonitrile (AN) was infiltrated in the voids of the F-SiO2 colloidal crystal microspheres, and in-situ induced by 60Co γ-ray to polymerize into polyacrylonitrile (PAN). After the PAN-infiltrated F-SiO2 colloidal crystal microspheres were carbonized and etched with HF solution, novel micron-sized inverse-opal N-doped carbon (IO-NC) microspheres consisting of hollow carbon nanoparticles with a hierarchical macro/meso-porous inner surface were obtained. The IO-NC microspheres have a specific surface area as high as 266.4 m2/g and a molar ratio of C/N of 5. They have a good dispersibility in water, and show a high adsorption capacity towards rhodamine B (RhB) up to 137.28 mg/(g microsphere). This work offers a way to obtain novel micron-sized hierarchical macro/meso-porous N-doped carbon microspheres, which opens a new idea to prepare high-performance hierarchical porous carbon materials.
2021, 32(2): 870-874
doi: 10.1016/j.cclet.2020.06.014
Abstract:
Specific topographic Ni anchoring on reduced graphene oxide (rGO) composites show an astronomical potential as effective wave absorbers due to the synergistic electromagnetic loss effects. Herein, Ni/rGO composites with different topography were successfully prepared via hydrothermal in-situ reduction method. The structure and morphology characteristics revealed that particle-like, chain-like, coin-like and flower-like Ni were closely anchored onto rGO, respectively. The electromagnetic wave absorption (EMA) performance revealed that chain-like Ni/rGO exhibited the optimal reflection loss of -43.7 dB with a thickness of 1.8 mm as well as the EAB of 6.1 GHz at 2.0 mm among all samples due to the good impedance match and the synergistic dielectric and magnetic losses. Besides, one conclusion can be drawn that excellent magnetic coupling effect and impedance matching were the main reasons for significantly improving the EMA performance. Considering the systematic dependence of morphology on EMA, this work provides a perspective for designing high-performance absorbing materials.
Specific topographic Ni anchoring on reduced graphene oxide (rGO) composites show an astronomical potential as effective wave absorbers due to the synergistic electromagnetic loss effects. Herein, Ni/rGO composites with different topography were successfully prepared via hydrothermal in-situ reduction method. The structure and morphology characteristics revealed that particle-like, chain-like, coin-like and flower-like Ni were closely anchored onto rGO, respectively. The electromagnetic wave absorption (EMA) performance revealed that chain-like Ni/rGO exhibited the optimal reflection loss of -43.7 dB with a thickness of 1.8 mm as well as the EAB of 6.1 GHz at 2.0 mm among all samples due to the good impedance match and the synergistic dielectric and magnetic losses. Besides, one conclusion can be drawn that excellent magnetic coupling effect and impedance matching were the main reasons for significantly improving the EMA performance. Considering the systematic dependence of morphology on EMA, this work provides a perspective for designing high-performance absorbing materials.
2021, 32(2): 875-879
doi: 10.1016/j.cclet.2020.06.015
Abstract:
A novel kind of fully bio-based PSAs were obtained through the curing reaction between two components derived from the plant oils: carboxyl-terminated polyricinoleate (PRA) from the castor oil and epoxidized soybean oil (ESO). The gel content, glass transition temperature (Tg), rheological behavior, tensile strength, creep resistance and 180° peel strength of the PSAs were feasibly tailored by adjusting the component ratio of ESO to PRA. At low cross-linking level, the PSAs behaved like a viscous liquid and did not possess enough cohesiveness to sustain the mechanical stress during peeling. The PSAs cross-linked at or near the optimal stoichiometric conditions displayed an adhesive (interfacial) failure between the substrate and the adhesive layer, which were associated with the lowest adhesion levels. The PSAs with the dosage amount of ESO ranging from 10~20 wt% were tacky and flexible, which exhibited 180° peel strength ranging from 0.4~2.3 N/cm; and could be easily removed without any residues on the adherend. The process for the preparation of the fully bio-based PSAs was environmentally friendly without using any organic solvent or other toxic chemical, herein showing the great potential as sustainable materials.
A novel kind of fully bio-based PSAs were obtained through the curing reaction between two components derived from the plant oils: carboxyl-terminated polyricinoleate (PRA) from the castor oil and epoxidized soybean oil (ESO). The gel content, glass transition temperature (Tg), rheological behavior, tensile strength, creep resistance and 180° peel strength of the PSAs were feasibly tailored by adjusting the component ratio of ESO to PRA. At low cross-linking level, the PSAs behaved like a viscous liquid and did not possess enough cohesiveness to sustain the mechanical stress during peeling. The PSAs cross-linked at or near the optimal stoichiometric conditions displayed an adhesive (interfacial) failure between the substrate and the adhesive layer, which were associated with the lowest adhesion levels. The PSAs with the dosage amount of ESO ranging from 10~20 wt% were tacky and flexible, which exhibited 180° peel strength ranging from 0.4~2.3 N/cm; and could be easily removed without any residues on the adherend. The process for the preparation of the fully bio-based PSAs was environmentally friendly without using any organic solvent or other toxic chemical, herein showing the great potential as sustainable materials.
2021, 32(2): 880-884
doi: 10.1016/j.cclet.2020.06.036
Abstract:
Ion diffusion kinetics, depending on the size, tortuosity, connectivity of the channels, greatly affects the rate performance of the electrodes. Two-dimensional materials (2DMs) has emerged as promising electrode materials in the past decades. However, the applications of 2DMs electrodes are limited by the strong restacking problem, which leads to a poor rate capability. In this work, we for the first time mediated the morphology of molybdenum disulfide (MoS2) nanosheets via a facile coagulation method; abundant sheet crumples were induced, which greatly enhance their surface accessibility and thus benefit the ion diffusion kinetics. Consequently, the crumpled-MoS2 electrodes follow a capacitive Na-ion charge-storage mechanism to a large extent. Importantly, we demonstrate the special role of organic cations in the inter-sheet assembly configuration, in sharp contrast with that of alkali/alkaline-earth ones. We propose that organic cations cause edge/face contact of the sheets, instead of the face/face contact, thus affording a house-of-cards structure.
Ion diffusion kinetics, depending on the size, tortuosity, connectivity of the channels, greatly affects the rate performance of the electrodes. Two-dimensional materials (2DMs) has emerged as promising electrode materials in the past decades. However, the applications of 2DMs electrodes are limited by the strong restacking problem, which leads to a poor rate capability. In this work, we for the first time mediated the morphology of molybdenum disulfide (MoS2) nanosheets via a facile coagulation method; abundant sheet crumples were induced, which greatly enhance their surface accessibility and thus benefit the ion diffusion kinetics. Consequently, the crumpled-MoS2 electrodes follow a capacitive Na-ion charge-storage mechanism to a large extent. Importantly, we demonstrate the special role of organic cations in the inter-sheet assembly configuration, in sharp contrast with that of alkali/alkaline-earth ones. We propose that organic cations cause edge/face contact of the sheets, instead of the face/face contact, thus affording a house-of-cards structure.
2021, 32(2): 885-889
doi: 10.1016/j.cclet.2020.07.004
Abstract:
Fe-based phosphates with excellent physical and chemical features are potential electrode materials for supercapacitors. In this work, we successfully synthesized Fe-based phosphates with different dimensions, morphologies, and compositions by one-step hydrothermal method. Influence factors on the chemical composition and morphology of the as-prepared materials were explored and the energy storage performance of the as-prepared samples were tested under the traditional three electrode system. Two-dimensional (2D) iron metaphosphate (Fe(PO3)3) showed the best electrochemical performance. For Fe(PO3)3 electrode materials, the layered structure can provide a larger specific surface area than the bulk structure, which is conducive to the diffusion and transport of electrolyte ions during charging-discharging and further improves the rate performance and cycle stability of supercapacitor. 2D Fe(PO3)3 and activated carbon were used as electrode materials to construct a 2D Fe(PO3)3//AC supercapacitor. The supercapacitor showed high energy density, high power density, and excellent cycling stability, which indicates 2D Fe(PO3)3 is a promising electrode material for supercapacitors.
Fe-based phosphates with excellent physical and chemical features are potential electrode materials for supercapacitors. In this work, we successfully synthesized Fe-based phosphates with different dimensions, morphologies, and compositions by one-step hydrothermal method. Influence factors on the chemical composition and morphology of the as-prepared materials were explored and the energy storage performance of the as-prepared samples were tested under the traditional three electrode system. Two-dimensional (2D) iron metaphosphate (Fe(PO3)3) showed the best electrochemical performance. For Fe(PO3)3 electrode materials, the layered structure can provide a larger specific surface area than the bulk structure, which is conducive to the diffusion and transport of electrolyte ions during charging-discharging and further improves the rate performance and cycle stability of supercapacitor. 2D Fe(PO3)3 and activated carbon were used as electrode materials to construct a 2D Fe(PO3)3//AC supercapacitor. The supercapacitor showed high energy density, high power density, and excellent cycling stability, which indicates 2D Fe(PO3)3 is a promising electrode material for supercapacitors.
2021, 32(2): 890-894
doi: 10.1016/j.cclet.2020.07.008
Abstract:
Lithium polymer batteries (LPBs) rely on a high ion transport to gain improved cell performance. Thermostable and porous gel polymer electrolytes (GPEs) have attracted much attention due to their excellent properties in electrolyte wettability and ionic conductivity. In this work, iron-nickel-cobalt trimetal Prussian blue analogue (PBA) nanocubes are filled into the electrospun polyacrylonitrile (PAN)-based membranes to generate GPE composites with morphological superiority consisting of fine fibers and interconnected pores. The thus obtained PBA@PAN fibrous membrane showcases good thermal stability, high porosity and electrolyte uptake, as well as a peak ionic conductivity of 2.7 mS/cm with the addition of 10% PBA. Consequently, the assembled lithium iron phosphate (LiFePO4) battery using PBA@PAN-10 as the GPE delivers a high capacity of 152.2 mAh/g at 0.2 C and an ultralow capacity decay of 0.09% per cycle in a long-term cycle life of 350 cycles at 1 C, endorsing its promising applications in LPBs.
Lithium polymer batteries (LPBs) rely on a high ion transport to gain improved cell performance. Thermostable and porous gel polymer electrolytes (GPEs) have attracted much attention due to their excellent properties in electrolyte wettability and ionic conductivity. In this work, iron-nickel-cobalt trimetal Prussian blue analogue (PBA) nanocubes are filled into the electrospun polyacrylonitrile (PAN)-based membranes to generate GPE composites with morphological superiority consisting of fine fibers and interconnected pores. The thus obtained PBA@PAN fibrous membrane showcases good thermal stability, high porosity and electrolyte uptake, as well as a peak ionic conductivity of 2.7 mS/cm with the addition of 10% PBA. Consequently, the assembled lithium iron phosphate (LiFePO4) battery using PBA@PAN-10 as the GPE delivers a high capacity of 152.2 mAh/g at 0.2 C and an ultralow capacity decay of 0.09% per cycle in a long-term cycle life of 350 cycles at 1 C, endorsing its promising applications in LPBs.
2021, 32(2): 895-899
doi: 10.1016/j.cclet.2020.07.014
Abstract:
Metal organic framework (MOF) has been confirmed as the promising precursor to develop the conversion-typed anode materials of sodium-ion batteries (SIBs) because of the tunable structure design and simple functional modification. Here, we prepare the ultrasmall Ni3S2 nanocrystals embedded into N-doped porous carbon nanoparticles using the scalable Ni-MOF as precursor (denoted as Ni3S2@NPC). The ultrasmall size of Ni3S2 can work for accelerated electron/ion transfer to facilitate the electrochemical reaction kinetics. Moreover, the robust conductivity network originated from N-doped porous carbon nanoparticles can not only improve the electron conductivity, but also enhance the electrode integrity and stability of the electrode/electrolyte interface. In addition, the N heteroatoms provide extra Na storage sites. Accordingly, the electrode delivers the obviously competitive capacities and high-power output with respect to the currently reported Ni3S2/C composites. This study provides a scalable and universal strategy to develop the advanced transition metal sulfides for practically feasible SIBs.
Metal organic framework (MOF) has been confirmed as the promising precursor to develop the conversion-typed anode materials of sodium-ion batteries (SIBs) because of the tunable structure design and simple functional modification. Here, we prepare the ultrasmall Ni3S2 nanocrystals embedded into N-doped porous carbon nanoparticles using the scalable Ni-MOF as precursor (denoted as Ni3S2@NPC). The ultrasmall size of Ni3S2 can work for accelerated electron/ion transfer to facilitate the electrochemical reaction kinetics. Moreover, the robust conductivity network originated from N-doped porous carbon nanoparticles can not only improve the electron conductivity, but also enhance the electrode integrity and stability of the electrode/electrolyte interface. In addition, the N heteroatoms provide extra Na storage sites. Accordingly, the electrode delivers the obviously competitive capacities and high-power output with respect to the currently reported Ni3S2/C composites. This study provides a scalable and universal strategy to develop the advanced transition metal sulfides for practically feasible SIBs.
2021, 32(2): 900-905
doi: 10.1016/j.cclet.2020.07.016
Abstract:
With increasing demand for renewable energy, graphene-like BC3 monolayer as high performance electrode materials for lithium and sodium batteries are drawing more attention recently. However, its structural stability, potassium storage properties and strain effect on adsorptionproperties of alkali metal ions have not been reported yet. In this work, phonon spectra, AIMD simulations and elastic constants of graphene-like BC3 monolayer are investigated. Our results show that graphene-like BC3 monolayer possesses excellent structural stability and the maximum theoretical potassium storage capacity can reach up to 1653 mAh/g with the corresponding open circuit voltages 0.66 V. Due to potassium atom can be effectively adsorbed at the most energetically favorable h-CC site with obvious charge transfer, making adsorbed graphene-like BC3 monolayer change from semiconductor to metal which is really good for electrode utilization. Moreover, the migrations potassium atom on the graphene-like BC3 monolayer is rather fast with the diffusion barriers as low as 0.12 eV, comparing lithium atom with a relatively large diffusion barrier of 0.46 eV. Additionally, the tensile strains applied on the graphene-like BC3 monolayer have marginal effect on the adsorption and diffusion performances of lithium, sodium and potassium atoms.
With increasing demand for renewable energy, graphene-like BC3 monolayer as high performance electrode materials for lithium and sodium batteries are drawing more attention recently. However, its structural stability, potassium storage properties and strain effect on adsorptionproperties of alkali metal ions have not been reported yet. In this work, phonon spectra, AIMD simulations and elastic constants of graphene-like BC3 monolayer are investigated. Our results show that graphene-like BC3 monolayer possesses excellent structural stability and the maximum theoretical potassium storage capacity can reach up to 1653 mAh/g with the corresponding open circuit voltages 0.66 V. Due to potassium atom can be effectively adsorbed at the most energetically favorable h-CC site with obvious charge transfer, making adsorbed graphene-like BC3 monolayer change from semiconductor to metal which is really good for electrode utilization. Moreover, the migrations potassium atom on the graphene-like BC3 monolayer is rather fast with the diffusion barriers as low as 0.12 eV, comparing lithium atom with a relatively large diffusion barrier of 0.46 eV. Additionally, the tensile strains applied on the graphene-like BC3 monolayer have marginal effect on the adsorption and diffusion performances of lithium, sodium and potassium atoms.
2021, 32(2): 906-909
doi: 10.1016/j.cclet.2020.07.015
Abstract:
We design a ratiometric fluorescent sensing platform for bleomycin (BLM) by using proximity-dependent DNA-templated silver nanoclusters (DNA-AgNCs) probe. This ratiometric sensing system is constructed with DNA-AgNCs as single fluorophore. The proposed strategy is based on the two following facts: (1) a covert DNA can approach and transform the DNA-AgNCs with green emission (G-DNA-AgNCs) into red emission through hybridization reaction. (2) The specific cleavage of the convert DNA by BLM in the presence of Fe(II) inhibits the discoloration of G-DNA-AgNCs. Thus, benefiting from the specific recognition of BLM and unique properties of G-DNA-AgNCs, a highly-sensitive ratiometric sensor for BLM has been successfully developed. The detection limit is as low as 30 pmol/L. This label-free fluorescence probe possesses advantages of convenient synthetic process and low cost. Moreover, this ratiometric method has been applied to the detection of BLM in human serum samples, illustrating a promising tool for analysis of BLM in cancer therapy.
We design a ratiometric fluorescent sensing platform for bleomycin (BLM) by using proximity-dependent DNA-templated silver nanoclusters (DNA-AgNCs) probe. This ratiometric sensing system is constructed with DNA-AgNCs as single fluorophore. The proposed strategy is based on the two following facts: (1) a covert DNA can approach and transform the DNA-AgNCs with green emission (G-DNA-AgNCs) into red emission through hybridization reaction. (2) The specific cleavage of the convert DNA by BLM in the presence of Fe(II) inhibits the discoloration of G-DNA-AgNCs. Thus, benefiting from the specific recognition of BLM and unique properties of G-DNA-AgNCs, a highly-sensitive ratiometric sensor for BLM has been successfully developed. The detection limit is as low as 30 pmol/L. This label-free fluorescence probe possesses advantages of convenient synthetic process and low cost. Moreover, this ratiometric method has been applied to the detection of BLM in human serum samples, illustrating a promising tool for analysis of BLM in cancer therapy.
2021, 32(2): 910-913
doi: 10.1016/j.cclet.2020.07.021
Abstract:
The nano-Si/graphite nanocomposites are the promising anodes candidates for high-energy lithium-ion batteries because of their high theoretical capacities and low volume variations. However, the nano-Si has a severe tendency to separate from the graphite substrate due to the inherently weak bonding between them, thus leading to the deteriorated cycling performance and low Coulombic efficiency. Herein, we design a robust nano-Si/graphite nanocomposite structure with strong interfacial adhesion caused by the Si—Ti and Ti—C covalent bonds. The abundant Si—Ti and Ti—C bonds formed between nano-Si and graphite greatly enhance the interfacial adhesion force, resulting in the highly stabilized and integrated electrode structure during battery cycling. Consequently, the as-obtained nano-Si/graphite anodes deliver a high capacity retention of 90.0% after 420 cycles at 0.5 C with an average Coulombic efficiency of 99.5%; moreover, a high initial Coulombic efficiency of 90.2% is achieved. Significantly, this work provides a novel strategy to address the poor interfacial adhesion between nano-Si and graphite, which can be applied to other nano-Si based composites anodes.
The nano-Si/graphite nanocomposites are the promising anodes candidates for high-energy lithium-ion batteries because of their high theoretical capacities and low volume variations. However, the nano-Si has a severe tendency to separate from the graphite substrate due to the inherently weak bonding between them, thus leading to the deteriorated cycling performance and low Coulombic efficiency. Herein, we design a robust nano-Si/graphite nanocomposite structure with strong interfacial adhesion caused by the Si—Ti and Ti—C covalent bonds. The abundant Si—Ti and Ti—C bonds formed between nano-Si and graphite greatly enhance the interfacial adhesion force, resulting in the highly stabilized and integrated electrode structure during battery cycling. Consequently, the as-obtained nano-Si/graphite anodes deliver a high capacity retention of 90.0% after 420 cycles at 0.5 C with an average Coulombic efficiency of 99.5%; moreover, a high initial Coulombic efficiency of 90.2% is achieved. Significantly, this work provides a novel strategy to address the poor interfacial adhesion between nano-Si and graphite, which can be applied to other nano-Si based composites anodes.
2021, 32(2): 914-917
doi: 10.1016/j.cclet.2020.07.025
Abstract:
Porous structure and heteroatom doping are two key parameters for significantly boosting the capacitive performance of graphene-based materials. Herein, we report a facile approach to prepare one-dimensional (1D) nitrogen-doped holey graphene nanoscrolls (NHGNSs) through cold quenching treatment of two-dimensional graphene oxide sheets, followed by thermal annealing in the successive atmosphere of NH3 and air. Benefiting from the synergy of the unique 1D tubular morphology, abundant nanoholes and nitrogen doping, the NHGNSs exhibit a high specific capacitance of 126 F/g at 1 A/g in ionic liquid electrolyte and excellent rate capability with 81% of the capacitance retained at 20 A/g. Furthermore, the fabricated symmetric supercapacitors based on NHGNSs achieve both high energy density of 53.5 Wh/kg at 875 W/kg and high power density of 17.5 kW/kg at 43.4 Wh/kg. The simple synthetic process and superior electrochemical performance suggest the great potential of NHGNSs for supercapacitor application.
Porous structure and heteroatom doping are two key parameters for significantly boosting the capacitive performance of graphene-based materials. Herein, we report a facile approach to prepare one-dimensional (1D) nitrogen-doped holey graphene nanoscrolls (NHGNSs) through cold quenching treatment of two-dimensional graphene oxide sheets, followed by thermal annealing in the successive atmosphere of NH3 and air. Benefiting from the synergy of the unique 1D tubular morphology, abundant nanoholes and nitrogen doping, the NHGNSs exhibit a high specific capacitance of 126 F/g at 1 A/g in ionic liquid electrolyte and excellent rate capability with 81% of the capacitance retained at 20 A/g. Furthermore, the fabricated symmetric supercapacitors based on NHGNSs achieve both high energy density of 53.5 Wh/kg at 875 W/kg and high power density of 17.5 kW/kg at 43.4 Wh/kg. The simple synthetic process and superior electrochemical performance suggest the great potential of NHGNSs for supercapacitor application.
2021, 32(2): 918-922
doi: 10.1016/j.cclet.2020.07.023
Abstract:
By taking the functional advantages of both pyrazolate and carboxylate ligands, a unique dual-functional pyrazolate-carboxylate ligand acid, 4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid (H3PCBA) was designed and synthesized. Using it, a new Co(II)-based metal-organic framework (MOF), Co3(PCBA)2(H2O)2 (BUT-75) has been constructed. It revealed a (3,6)-connected net based on the 6-connected linear trinuclear metal node, and showed good chemical stability in a wide pH range from 3 to 12 at room temperature, as well as in boiling water. Due to the presence of rich exposed Co(II) sites in pores, BUT-75 presented high selective CO2 adsorption capacity over N2 at 298 K. Simultaneously, it demonstrated fine catalytic performance for the cycloaddition of CO2 with epoxides into cyclic carbonates under ambient conditions. This work has not only enriched the MOF community through integrating diverse functionalities into one ligand but also contributed a versatile platform for CO2 fixation, thereby pushing MOF chemistry forward by stability enhancement and application expansion.
By taking the functional advantages of both pyrazolate and carboxylate ligands, a unique dual-functional pyrazolate-carboxylate ligand acid, 4-(3,6-di(pyrazol-4-yl)-9-carbazol-9-yl)benzoic acid (H3PCBA) was designed and synthesized. Using it, a new Co(II)-based metal-organic framework (MOF), Co3(PCBA)2(H2O)2 (BUT-75) has been constructed. It revealed a (3,6)-connected net based on the 6-connected linear trinuclear metal node, and showed good chemical stability in a wide pH range from 3 to 12 at room temperature, as well as in boiling water. Due to the presence of rich exposed Co(II) sites in pores, BUT-75 presented high selective CO2 adsorption capacity over N2 at 298 K. Simultaneously, it demonstrated fine catalytic performance for the cycloaddition of CO2 with epoxides into cyclic carbonates under ambient conditions. This work has not only enriched the MOF community through integrating diverse functionalities into one ligand but also contributed a versatile platform for CO2 fixation, thereby pushing MOF chemistry forward by stability enhancement and application expansion.
2021, 32(2): 923-925
doi: 10.1016/j.cclet.2020.04.004
Abstract:
In this work, titanium-capped cobalt clathrochelates have been applied as secondary building units (SBUs) for the construction of supramolecular rings. Two heterometallic wheel-like [Ti6Co12] complexes based on cobalt clathrochelates, [C6H15N4]2[TiCo2(μ2-Oipr)(Oipr)2(Dmg)3]6 (2, Dmg=dimethylglyoxime) and H6[TiCo2(μ2-Oipr)(Oipr)2(Dmg)3]6 (3), have been successfully synthesized and characterized. The supramolecular stacking modes of these wheels are largely dependent on the applied synthetic conditions, which further impact their gas adsorption properties.
In this work, titanium-capped cobalt clathrochelates have been applied as secondary building units (SBUs) for the construction of supramolecular rings. Two heterometallic wheel-like [Ti6Co12] complexes based on cobalt clathrochelates, [C6H15N4]2[TiCo2(μ2-Oipr)(Oipr)2(Dmg)3]6 (2, Dmg=dimethylglyoxime) and H6[TiCo2(μ2-Oipr)(Oipr)2(Dmg)3]6 (3), have been successfully synthesized and characterized. The supramolecular stacking modes of these wheels are largely dependent on the applied synthetic conditions, which further impact their gas adsorption properties.
2021, 32(2): 926-931
doi: 10.1016/j.cclet.2020.06.037
Abstract:
Zinc-ion hybrid super-capacitors are regarded as promising safe energy storage systems. However, the relatively low volumetric energy density has become the main bottlenecks in practical applications of portable electronic devices. In this work, the zinc-ion hybrid super-capacitor with high volumetric energy density and superb cycle stability had been constructed which employing the high-density three-dimensional graphene hydrogel as cathode and Zn foil used as anode in 1 mol/L ZnSO4 electrolyte. Benefiting from the abundant ion transport paths and the abundant active sites for graphene hydrogel with high density and porous structure, the zinc-ion hybrid super-capacitor exhibited an extremely high volumetric energy density of 118.42 Wh/L and a superb power density of 24.00 kW/L, as well as an excellent long cycle life (80% retention after 30,000 cycles at 10 A/g), which was superior to the volumetric energy density of the reported zinc-ion hybrid super-capacitors. This device, based on the fast ion adsorption/desorption on the capacitor-type graphene cathode and reversible Zn2+ plating/stripping on the battery-type Zn anode, which will inspire the development of zinc-ion hybrid super-capacitor in miniaturized devices.
Zinc-ion hybrid super-capacitors are regarded as promising safe energy storage systems. However, the relatively low volumetric energy density has become the main bottlenecks in practical applications of portable electronic devices. In this work, the zinc-ion hybrid super-capacitor with high volumetric energy density and superb cycle stability had been constructed which employing the high-density three-dimensional graphene hydrogel as cathode and Zn foil used as anode in 1 mol/L ZnSO4 electrolyte. Benefiting from the abundant ion transport paths and the abundant active sites for graphene hydrogel with high density and porous structure, the zinc-ion hybrid super-capacitor exhibited an extremely high volumetric energy density of 118.42 Wh/L and a superb power density of 24.00 kW/L, as well as an excellent long cycle life (80% retention after 30,000 cycles at 10 A/g), which was superior to the volumetric energy density of the reported zinc-ion hybrid super-capacitors. This device, based on the fast ion adsorption/desorption on the capacitor-type graphene cathode and reversible Zn2+ plating/stripping on the battery-type Zn anode, which will inspire the development of zinc-ion hybrid super-capacitor in miniaturized devices.
2021, 32(2): 932-937
doi: 10.1016/j.cclet.2020.03.047
Abstract:
A novel water-soluble red-emissive AIE fluorescence probe for cysteine (Cys) in situ was prepared and the performance of selectivity and sensitivity has been carefully investigated in this study. The probe was established on the electrostatic interaction of sulfonate functionalized tetraphenylethene (TPE) and polycation generated by the reaction between a polymer bearing dinitrobenzenesulfonate groups and Cys. From the experimental results, it was easy to distinguish Cys from glutathione (GSH) and homocysteine (Hcy) with a detection limit of 73 nmol/L. The assay system also possessed strong anti-interference ability against multitudinous amino acids. The Stokes shift was 142 nm and the emission ranged from 550 nm to 850 nm. In addition, double responses in fluorescence and ultraviolet-visible spectra also make the red-emissive assay ideal for sensitive detection and quantification of Cys for most purposes, especially in-situ monitoring of Cys in aqueous medium.
A novel water-soluble red-emissive AIE fluorescence probe for cysteine (Cys) in situ was prepared and the performance of selectivity and sensitivity has been carefully investigated in this study. The probe was established on the electrostatic interaction of sulfonate functionalized tetraphenylethene (TPE) and polycation generated by the reaction between a polymer bearing dinitrobenzenesulfonate groups and Cys. From the experimental results, it was easy to distinguish Cys from glutathione (GSH) and homocysteine (Hcy) with a detection limit of 73 nmol/L. The assay system also possessed strong anti-interference ability against multitudinous amino acids. The Stokes shift was 142 nm and the emission ranged from 550 nm to 850 nm. In addition, double responses in fluorescence and ultraviolet-visible spectra also make the red-emissive assay ideal for sensitive detection and quantification of Cys for most purposes, especially in-situ monitoring of Cys in aqueous medium.
2021, 32(2): 938-942
doi: 10.1016/j.cclet.2020.06.013
Abstract:
Numerous scientists are in the pursuit of energy storage materials with high energy and high power density by assembly of electrochemically active materials into conductive scaffolds, owing to the emerging need for next-generation energy storage devices. In this architectures, the active materials bonded to the conductive scaffold can provide a robust and free-standing structure, which is crucial to the fabrication of materials with high gravimetric capacity. Thus, hierarchical copper-cobalt-nickel ternary oxide (CuCoNi-oxide) nanowire arrays grown from copper foam were successfully fabricated as free-standing anode materials for lithium ion batteries (LIBs). CuCoNi-oxide nanowire arrays could provide more active sites owing to the hyperbranched structure, leading to a better specific capacity of 1191 mAh/g, cycle performance of 73% retention in comparison to CuO nanowire structure, which exhibited a specific capacity of 1029 mAh/g and capacity retention of 43%, respectively.
Numerous scientists are in the pursuit of energy storage materials with high energy and high power density by assembly of electrochemically active materials into conductive scaffolds, owing to the emerging need for next-generation energy storage devices. In this architectures, the active materials bonded to the conductive scaffold can provide a robust and free-standing structure, which is crucial to the fabrication of materials with high gravimetric capacity. Thus, hierarchical copper-cobalt-nickel ternary oxide (CuCoNi-oxide) nanowire arrays grown from copper foam were successfully fabricated as free-standing anode materials for lithium ion batteries (LIBs). CuCoNi-oxide nanowire arrays could provide more active sites owing to the hyperbranched structure, leading to a better specific capacity of 1191 mAh/g, cycle performance of 73% retention in comparison to CuO nanowire structure, which exhibited a specific capacity of 1029 mAh/g and capacity retention of 43%, respectively.
2021, 32(2): 943-946
doi: 10.1016/j.cclet.2021.02.003
Abstract:
With the development of single-molecule detection and super-resolution fluorescence imaging, rhodamine dyes gain new life. Through the modification of the N-substituents and the replacement of the oxygen atom in xanthene, the wavelength and brightness can be effectively changed. However, the spectra of rhodamine, especially due to the balance between ring-closed non-fluorescent lactone and ring-opened fluorescent zwitterion/cation, are sensitive to interference from various environmental factors. In this way, the spectral data of various rhodamines reported by different research groups under different test conditions lacked comparability, sometimes even lacked accuracy. In order to meet the requirements for the accuracy and uniformity of spectral data in the research of single molecule imaging and dye structure-fluorescence relationship study, we have tested the spectra of fifteen rhodamine dyes that cover the visible and near-infrared regions under exactly the same conditions. By studying the dependence of the spectra on dye concentrations, it was confirmed that 1 μmol/L was ideal for detection less from the interference of dye molecule aggregation. We provide comprehensive and reliable spectral data of these fifteen dyes, which are expected to be used as references for future research. And the direct comparison of different rhodamine spectra would help to understand the structure-fluorescence relationship of rhodamines.
With the development of single-molecule detection and super-resolution fluorescence imaging, rhodamine dyes gain new life. Through the modification of the N-substituents and the replacement of the oxygen atom in xanthene, the wavelength and brightness can be effectively changed. However, the spectra of rhodamine, especially due to the balance between ring-closed non-fluorescent lactone and ring-opened fluorescent zwitterion/cation, are sensitive to interference from various environmental factors. In this way, the spectral data of various rhodamines reported by different research groups under different test conditions lacked comparability, sometimes even lacked accuracy. In order to meet the requirements for the accuracy and uniformity of spectral data in the research of single molecule imaging and dye structure-fluorescence relationship study, we have tested the spectra of fifteen rhodamine dyes that cover the visible and near-infrared regions under exactly the same conditions. By studying the dependence of the spectra on dye concentrations, it was confirmed that 1 μmol/L was ideal for detection less from the interference of dye molecule aggregation. We provide comprehensive and reliable spectral data of these fifteen dyes, which are expected to be used as references for future research. And the direct comparison of different rhodamine spectra would help to understand the structure-fluorescence relationship of rhodamines.
2021, 32(2): 947-947
doi: 10.1016/j.cclet.2021.02.064
Abstract:
2021, 32(2): 609-619
doi: 10.1016/j.cclet.2020.10.025
Abstract:
The abuse of antibiotics will cause an increase of drug-resistant strains and environmental pollution, which in turn will affect human health. Therefore, it is important to develop effective detection techniques to determine the level of antibiotics contamination in various fields. Compared with traditional detection methods, electrochemical sensors have received extensive attention due to their advantages such as high sensitivity, low detection limit, and good selectivity. In this mini review, we summarized the latest developments and new trends in electrochemical sensors for antibiotics. Here, modification methods and materials of electrode are discussed. We also pay more attention to the practical applications of antibiotics electrochemical sensors in different fields. In addition, the existing problems and the future challenges ahead have been proposed. We hope that this review can provide new ideas for the development of electrochemical sensors for antibiotics in the future.
The abuse of antibiotics will cause an increase of drug-resistant strains and environmental pollution, which in turn will affect human health. Therefore, it is important to develop effective detection techniques to determine the level of antibiotics contamination in various fields. Compared with traditional detection methods, electrochemical sensors have received extensive attention due to their advantages such as high sensitivity, low detection limit, and good selectivity. In this mini review, we summarized the latest developments and new trends in electrochemical sensors for antibiotics. Here, modification methods and materials of electrode are discussed. We also pay more attention to the practical applications of antibiotics electrochemical sensors in different fields. In addition, the existing problems and the future challenges ahead have been proposed. We hope that this review can provide new ideas for the development of electrochemical sensors for antibiotics in the future.
2021, 32(2): 620-634
doi: 10.1016/j.cclet.2020.07.029
Abstract:
As a new type of two-dimensional material, MXene's unique layered structure, outstanding electrical conductivity, low density, tunable surface chemistry, and solution processability make it receive extensive attention in various fields, especially for the lightweight shielding materials since the report on electromagnetic interference (EMI) shielding of 2D Ti3C2Tx in 2016. In this review, the progress on the MXenes material including their synthetic strategies, properties and EMI application is highlighted. First, the recent advance on the different synthesis methods and properties of MXene is summarized. According to their intrinsic characteristics, the application of MXene in EMI fields is then discussed. Finally, the challenges and perspective on the future development of MXene in low-cost preparation and practical application are proposed.
As a new type of two-dimensional material, MXene's unique layered structure, outstanding electrical conductivity, low density, tunable surface chemistry, and solution processability make it receive extensive attention in various fields, especially for the lightweight shielding materials since the report on electromagnetic interference (EMI) shielding of 2D Ti3C2Tx in 2016. In this review, the progress on the MXenes material including their synthetic strategies, properties and EMI application is highlighted. First, the recent advance on the different synthesis methods and properties of MXene is summarized. According to their intrinsic characteristics, the application of MXene in EMI fields is then discussed. Finally, the challenges and perspective on the future development of MXene in low-cost preparation and practical application are proposed.
2021, 32(2): 635-641
doi: 10.1016/j.cclet.2020.04.053
Abstract:
Nanoarchitectonics provide versatile opportunities for modifying the properties of coordination polymers (CP) other than molecular engineering. Spatial-controlled etching focuses on the controlled disassembly of the frameworks. The etching method provides an excellent opportunity for tailoring the properties and functions of the CPs. Here, we discuss the mechanism for controlled etching of the CPs and summarized the two main strategies utilized so far. Several examples are illustrated to demonstrate recent developments in this area. Moreover, advantages of the etched CPs are summarized in several important applications, including energy storage, catalysis and nanomedicine.
Nanoarchitectonics provide versatile opportunities for modifying the properties of coordination polymers (CP) other than molecular engineering. Spatial-controlled etching focuses on the controlled disassembly of the frameworks. The etching method provides an excellent opportunity for tailoring the properties and functions of the CPs. Here, we discuss the mechanism for controlled etching of the CPs and summarized the two main strategies utilized so far. Several examples are illustrated to demonstrate recent developments in this area. Moreover, advantages of the etched CPs are summarized in several important applications, including energy storage, catalysis and nanomedicine.
2021, 32(2): 642-648
doi: 10.1016/j.cclet.2020.06.035
Abstract:
Imitating the signal transduction and transmembrane transport controlled by biological channels in the cell membrane, artificial nanochannels with a similar capability of sensing and transport are constructed as bionic nanochannels. To accomplish selective sensing and transport of biological analyte (as "guest"), the bionic nanochannels are modified with the artificial receptor (as "host"). Based on selective recognition between host and guest, bionic nanochannels translate the stimulus of the guest to electrochemical signal as sensors, and further regulate the transmission of guest as transporters. However, throughout all kinds of guests, the selective sensing and transport of ions and chiral molecules is a challenging problem. And throughout all hosts of ions and chiral molecules, the macrocyclic hosts with multisite of recognition show better selectivity, such as crown ethers, cyclodextrins, calixarenes, and pillararenes. In this article, we highlight recent advances in the macrocyclic host-based nanochannels for the selective sensing and transport of ionic and chiral guests, summarize the similarities and differences of different kinds of macrocyclic host-based nanochannels, and expect the research direction and application prospect.
Imitating the signal transduction and transmembrane transport controlled by biological channels in the cell membrane, artificial nanochannels with a similar capability of sensing and transport are constructed as bionic nanochannels. To accomplish selective sensing and transport of biological analyte (as "guest"), the bionic nanochannels are modified with the artificial receptor (as "host"). Based on selective recognition between host and guest, bionic nanochannels translate the stimulus of the guest to electrochemical signal as sensors, and further regulate the transmission of guest as transporters. However, throughout all kinds of guests, the selective sensing and transport of ions and chiral molecules is a challenging problem. And throughout all hosts of ions and chiral molecules, the macrocyclic hosts with multisite of recognition show better selectivity, such as crown ethers, cyclodextrins, calixarenes, and pillararenes. In this article, we highlight recent advances in the macrocyclic host-based nanochannels for the selective sensing and transport of ionic and chiral guests, summarize the similarities and differences of different kinds of macrocyclic host-based nanochannels, and expect the research direction and application prospect.
2021, 32(2): 649-659
doi: 10.1016/j.cclet.2020.07.040
Abstract:
Reliable technologies for CO2 capture and conversion (C3) are of vital importance for the establishment of a sustainable society. Metal-organic framework (MOF) composites have shown their compelling potentials for C3 due to the plentiful reticular chemistry of MOF structures and the synergistic catalysis between MOFs and the functional guests. This review focuses on the syntheses and catalytic applications towards C3 of MOF composites, which is divided into three sections. The first section gives a brief introduction about synthetic strategies of MOF composites. The second section discusses the recent progress of MOF composites in C3, including CO2 chemical fixation, hydrogenation, photoreduction, electroreduction and photoelectroreduction. The third section summarizes the challenges and future prospects of MOF composites for C3. We hope that this review cannot only provide an inspiration for the rational design of MOF composites for C3, but also stimulate more and more research works in this emerging area.
Reliable technologies for CO2 capture and conversion (C3) are of vital importance for the establishment of a sustainable society. Metal-organic framework (MOF) composites have shown their compelling potentials for C3 due to the plentiful reticular chemistry of MOF structures and the synergistic catalysis between MOFs and the functional guests. This review focuses on the syntheses and catalytic applications towards C3 of MOF composites, which is divided into three sections. The first section gives a brief introduction about synthetic strategies of MOF composites. The second section discusses the recent progress of MOF composites in C3, including CO2 chemical fixation, hydrogenation, photoreduction, electroreduction and photoelectroreduction. The third section summarizes the challenges and future prospects of MOF composites for C3. We hope that this review cannot only provide an inspiration for the rational design of MOF composites for C3, but also stimulate more and more research works in this emerging area.
2021, 32(2): 660-667
doi: 10.1016/j.cclet.2020.08.027
Abstract:
The N-heterocyclic carbene (NHC)-catalyzed reactions involving two-electron reaction pathway have been well-established. However, the development of NHC-catalyzed radical reactions is still in its infancy in terms of reaction types and enantioselectivity. In the past decade, several elegant NHC-catalyzed radical reactions have been developed, including NHC-catalyzed oxidation of aldehydes to esters, reductive coupling reactions using Breslow intermediate as SET reductant and NHC-catalyzed reactions via radical homoenolates, dienoaltes and trienolates. This review summarizes the recent advances in NHC-catalyzed reactions involving radical intermediates.
The N-heterocyclic carbene (NHC)-catalyzed reactions involving two-electron reaction pathway have been well-established. However, the development of NHC-catalyzed radical reactions is still in its infancy in terms of reaction types and enantioselectivity. In the past decade, several elegant NHC-catalyzed radical reactions have been developed, including NHC-catalyzed oxidation of aldehydes to esters, reductive coupling reactions using Breslow intermediate as SET reductant and NHC-catalyzed reactions via radical homoenolates, dienoaltes and trienolates. This review summarizes the recent advances in NHC-catalyzed reactions involving radical intermediates.
