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2018 Volume 29 Issue 3
2018, 29(3): 343-344
doi: 10.1016/j.cclet.2018.01.044
Abstract:
2018, 29(3): 345-352
doi: 10.1016/j.cclet.2018.01.001
Abstract:
China is a major producer of rhenium, which is widely used in aerospace technologies (as superalloy) and petrochemical industries (as catalyst). There is a gap between the demand and fact for the enrichment of rhenium, due to its rather small content (10-9) in the earth's crust. Also, there is no available single occurrence of mineral rhenium. Instead, the rhenium is associated with either molybdenum or copper (of up to 0.2% in content) as a by-product in metallurgical industry. This makes the separation of rhenium from the major mineral metals a challenge. The recent progresses in the separation and enrichment of rhenium were reviewed in this paper, especially, the advances in China. The details of varied separation methods used either in laboratories or factories, such as ion-exchange, solvent extraction, separation utilizing extractive resins, liquid membrane, or novel materials, etc., were elaborated. Comparison of the different methods was disclosed and an outlook on the rhenium chemistry and industry in the future was brought forward.
China is a major producer of rhenium, which is widely used in aerospace technologies (as superalloy) and petrochemical industries (as catalyst). There is a gap between the demand and fact for the enrichment of rhenium, due to its rather small content (10-9) in the earth's crust. Also, there is no available single occurrence of mineral rhenium. Instead, the rhenium is associated with either molybdenum or copper (of up to 0.2% in content) as a by-product in metallurgical industry. This makes the separation of rhenium from the major mineral metals a challenge. The recent progresses in the separation and enrichment of rhenium were reviewed in this paper, especially, the advances in China. The details of varied separation methods used either in laboratories or factories, such as ion-exchange, solvent extraction, separation utilizing extractive resins, liquid membrane, or novel materials, etc., were elaborated. Comparison of the different methods was disclosed and an outlook on the rhenium chemistry and industry in the future was brought forward.
2018, 29(3): 399-404
doi: 10.1016/j.cclet.2017.09.031
Abstract:
Inkjet printing is a new fabricating method that can realize the precise film deposition. For polymer inks, the coil-stretch transition of polymer chains always impacts the ink droplet formation and a beads-on-a string structure filament is formed, thus generating unwanted satellite droplets. This review provides a short introduction of the dynamic process of the droplet formation. Then fluid rheological requirements for a printable polymer ink are summarized. Finally the strain hardening phenomenon of polymer chains in the filament formation and its impact on polymer ink-jetting are discussed. The research of viscoelastic polymer inks shows that rheological parameters and viscoelasticity are two key factors that determine the printability of polymer inks.
Inkjet printing is a new fabricating method that can realize the precise film deposition. For polymer inks, the coil-stretch transition of polymer chains always impacts the ink droplet formation and a beads-on-a string structure filament is formed, thus generating unwanted satellite droplets. This review provides a short introduction of the dynamic process of the droplet formation. Then fluid rheological requirements for a printable polymer ink are summarized. Finally the strain hardening phenomenon of polymer chains in the filament formation and its impact on polymer ink-jetting are discussed. The research of viscoelastic polymer inks shows that rheological parameters and viscoelasticity are two key factors that determine the printability of polymer inks.
2018, 29(3): 405-416
doi: 10.1016/j.cclet.2017.06.021
Abstract:
Among various gas sensing materials, metal oxide semiconductors have shown great potential as resistive type sensors. The ordered porous structural metal oxide semiconductors with well-defined meso-or macro-pores chemically synthesized via soft-templating method and nanocasting strategy have high porosity, highly interconnected pore channels and high surface area with enormous active sites for interacting with gaseous molecules. These features enable them good performance in gas sensing, including high sensitivity, fast response and recovery, good selectivity. This review gives a comprehensive summary about the porous metal oxides with focus on the synthesis methods, structure related properties, as well as the modification strategies for gas sensing improved performances.
Among various gas sensing materials, metal oxide semiconductors have shown great potential as resistive type sensors. The ordered porous structural metal oxide semiconductors with well-defined meso-or macro-pores chemically synthesized via soft-templating method and nanocasting strategy have high porosity, highly interconnected pore channels and high surface area with enormous active sites for interacting with gaseous molecules. These features enable them good performance in gas sensing, including high sensitivity, fast response and recovery, good selectivity. This review gives a comprehensive summary about the porous metal oxides with focus on the synthesis methods, structure related properties, as well as the modification strategies for gas sensing improved performances.
2018, 29(3): 417-422
doi: 10.1016/j.cclet.2017.08.040
Abstract:
Swainsonine (1) belongs to the family of indolizine alkaloid with strong neurologically toxic effects on herbivorous livestock. Recently, a great amount of evidence confirmed that this alkaloid displayed a wide range of bioactivities especially anti-cancer biological effects. The potential targets of swainsonine (1) were now revealed to be the mannosidase and Golgi mannosidase Ⅱ. Its low yield in plants or fungi, and no economically total synthesis route in practice as the key bottleneck restricted its further structureactivities relationships (SAR) investigation in drug discovery. This mini-review highlighted the biosynthetic advance of swainsonine (1) from 1973 to 2017 based on the results of isotope-labelled experiments and the recent research of its biosynthetic gene cluster, which could provide some thoughts for further biosynthetic investigation and efficiently biomimetic synthesis of swainsonine (1) in order to increase its output in practice.
Swainsonine (1) belongs to the family of indolizine alkaloid with strong neurologically toxic effects on herbivorous livestock. Recently, a great amount of evidence confirmed that this alkaloid displayed a wide range of bioactivities especially anti-cancer biological effects. The potential targets of swainsonine (1) were now revealed to be the mannosidase and Golgi mannosidase Ⅱ. Its low yield in plants or fungi, and no economically total synthesis route in practice as the key bottleneck restricted its further structureactivities relationships (SAR) investigation in drug discovery. This mini-review highlighted the biosynthetic advance of swainsonine (1) from 1973 to 2017 based on the results of isotope-labelled experiments and the recent research of its biosynthetic gene cluster, which could provide some thoughts for further biosynthetic investigation and efficiently biomimetic synthesis of swainsonine (1) in order to increase its output in practice.
2018, 29(3): 353-356
doi: 10.1016/j.cclet.2017.06.003
Abstract:
Cable-like Au@SiO2 Janus composite nanorods with PS and PEG grafting on both ends respectively are fabricated by skiving in combination of a post favorable modification. The cable-like Au@SiO2 composite nanofibers are synthesized in the channel of porous anodic aluminium oxide (AAO) membrane. After skiving, the corresponding composite nanorods are obtained. Following, PEG-SH and PS-SH are conjugated onto the two ends of the nanorods by a selective partial modification, respectively. Length and diameter of the Au@SiO2 Janus composite nanorods can be tuned controllably. It can be extended to fabricate a variety of different Janus nanorods with different compositions and microstructures.
Cable-like Au@SiO2 Janus composite nanorods with PS and PEG grafting on both ends respectively are fabricated by skiving in combination of a post favorable modification. The cable-like Au@SiO2 composite nanofibers are synthesized in the channel of porous anodic aluminium oxide (AAO) membrane. After skiving, the corresponding composite nanorods are obtained. Following, PEG-SH and PS-SH are conjugated onto the two ends of the nanorods by a selective partial modification, respectively. Length and diameter of the Au@SiO2 Janus composite nanorods can be tuned controllably. It can be extended to fabricate a variety of different Janus nanorods with different compositions and microstructures.
2018, 29(3): 357-360
doi: 10.1016/j.cclet.2017.11.006
Abstract:
This report investigated the ordering of the alky chain of sphingomyelin (SMs) monolayers induced by cholesterol at the air/water interface using high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS). The SFG spectra of the three nature sphingomyelin/cholesterol mixture monolayers with two concentrations of the cholesterol at the air/water interface are performed under different polarization combination. A new resolved CH2 symmetric stretching (d+, ~2834 cm-1) and the CH3 symmetric stretching (r+, ~2874 cm-1) mode are applied to characterize the conformational order in the sphingomyelin/cholesterol mixture monolayers. It was found that the cholesterol make the sphingosine backbones more conformational order. During this process, the conformational order of the N-linked acyl chain remains unaltered. Moreover, the sphingosine backbones of SMs have much larger contributions to gauche defects of SMs than one in the N-linked acyl chain. These results presented here not only shed lights on understanding of the interactions of sphingomyelin molecules with cholesterol molecules at interface but also demonstrates the ability of HR-BB-SFG to probe such complicated molecular systems.
This report investigated the ordering of the alky chain of sphingomyelin (SMs) monolayers induced by cholesterol at the air/water interface using high-resolution broadband sum frequency generation vibrational spectroscopy (HR-BB-SFG-VS). The SFG spectra of the three nature sphingomyelin/cholesterol mixture monolayers with two concentrations of the cholesterol at the air/water interface are performed under different polarization combination. A new resolved CH2 symmetric stretching (d+, ~2834 cm-1) and the CH3 symmetric stretching (r+, ~2874 cm-1) mode are applied to characterize the conformational order in the sphingomyelin/cholesterol mixture monolayers. It was found that the cholesterol make the sphingosine backbones more conformational order. During this process, the conformational order of the N-linked acyl chain remains unaltered. Moreover, the sphingosine backbones of SMs have much larger contributions to gauche defects of SMs than one in the N-linked acyl chain. These results presented here not only shed lights on understanding of the interactions of sphingomyelin molecules with cholesterol molecules at interface but also demonstrates the ability of HR-BB-SFG to probe such complicated molecular systems.
2018, 29(3): 361-365
doi: 10.1016/j.cclet.2017.11.009
Abstract:
We present a study of spectroscopic identification towards the molecular aggregates of zinc tetraphenylporphyrin (ZnTPP) illustrating how the energy states and intermolecular interactions determine the tunable properties of functional materials in condensation processes. Distinguishable fingerprints of ZnTPP nanorods and nanosheets are addressed utilizing X-ray diffraction (XRD), Raman and UV-vis absorption spectroscopies. Although these ZnTPPs are assigned to J-aggregation at different extent, the spectral analysis reveals a significant role of the intermolecular interactions associated with varying mesoscale architectures. Energy decomposition analysis (EDA) revealed that the varied ZnTPP aggregates are stabilized by altered dispersion interactions due to the dominant π…π stacking between the monomers.
We present a study of spectroscopic identification towards the molecular aggregates of zinc tetraphenylporphyrin (ZnTPP) illustrating how the energy states and intermolecular interactions determine the tunable properties of functional materials in condensation processes. Distinguishable fingerprints of ZnTPP nanorods and nanosheets are addressed utilizing X-ray diffraction (XRD), Raman and UV-vis absorption spectroscopies. Although these ZnTPPs are assigned to J-aggregation at different extent, the spectral analysis reveals a significant role of the intermolecular interactions associated with varying mesoscale architectures. Energy decomposition analysis (EDA) revealed that the varied ZnTPP aggregates are stabilized by altered dispersion interactions due to the dominant π…π stacking between the monomers.
2018, 29(3): 366-370
doi: 10.1016/j.cclet.2017.10.014
Abstract:
Ovalbumin-stabilized gold nanoclusters (OVA@AuNCs) were prepared with ascorbic acid as a reducing agent. This strategy could realize the synthesis of water-soluble OVA@AuNCs within 20 min. The asprepared fluorescent probe showed a red fluorescence emission at 630 nm. Moreover, the properties of the OVA@AuNCs were characterized by transmission electron microscope, dynamic light scattering, ultraviolet-visible spectroscopy, fluorescent spectroscopy. Based on the surface electron density decrease-induced fluorescence quenching mechanism, the OVA@AuNCs provided high sensitivity and selectivity for sensing copper ions. A good linear relationship was obtained between the fluorescence intensity of OVA@AuNCs and the concentration of copper ions in the range of 5.0-100.0 μmol/L (R2=0.999) with a detection limit of 640 nmol/L. Furthermore, the rat serum copper contents were determined by using the OVA@AuNCs based assay, indicating great potential of fluorescent probes for application in biological and clinical analysis.
Ovalbumin-stabilized gold nanoclusters (OVA@AuNCs) were prepared with ascorbic acid as a reducing agent. This strategy could realize the synthesis of water-soluble OVA@AuNCs within 20 min. The asprepared fluorescent probe showed a red fluorescence emission at 630 nm. Moreover, the properties of the OVA@AuNCs were characterized by transmission electron microscope, dynamic light scattering, ultraviolet-visible spectroscopy, fluorescent spectroscopy. Based on the surface electron density decrease-induced fluorescence quenching mechanism, the OVA@AuNCs provided high sensitivity and selectivity for sensing copper ions. A good linear relationship was obtained between the fluorescence intensity of OVA@AuNCs and the concentration of copper ions in the range of 5.0-100.0 μmol/L (R2=0.999) with a detection limit of 640 nmol/L. Furthermore, the rat serum copper contents were determined by using the OVA@AuNCs based assay, indicating great potential of fluorescent probes for application in biological and clinical analysis.
2018, 29(3): 371-373
doi: 10.1016/j.cclet.2017.08.006
Abstract:
In this work, a new star-shaped electron acceptor based on porphyrin as core, rhodanine and benzothiadiazole as end groups, was developed for non-fullerene solar cells. The molecule shows three distinct absorption regions due to the Soret and Q-bands of the porphyrin and the intramolecular charge transfer in the molecule. This molecule as electron acceptor was applied into non-fullerene solar cells by using a diketopyrrolopyrrole-based conjugated polymer as electron donor. An initial PCE of 1.9% was achieved with a broad photo-response from 300-850 nm. The results demonstrate that porphyrin can be used to design near-infrared electron acceptors for organic solar cells.
In this work, a new star-shaped electron acceptor based on porphyrin as core, rhodanine and benzothiadiazole as end groups, was developed for non-fullerene solar cells. The molecule shows three distinct absorption regions due to the Soret and Q-bands of the porphyrin and the intramolecular charge transfer in the molecule. This molecule as electron acceptor was applied into non-fullerene solar cells by using a diketopyrrolopyrrole-based conjugated polymer as electron donor. An initial PCE of 1.9% was achieved with a broad photo-response from 300-850 nm. The results demonstrate that porphyrin can be used to design near-infrared electron acceptors for organic solar cells.
2018, 29(3): 423-428
doi: 10.1016/j.cclet.2017.06.008
Abstract:
Controlling microstructure and thin film morphology of organic semiconductors by supramolecular arrangement is critical to improving their device performance. To realize well-controlling supramolecular assembly, a core-expanded naphthalene diimides derivative (1) was designed and synthesized as an n-type organic semiconductor and also as a halogen bonding (XB) donor that could form complementary XBs with 2, 2-dipyridine or 2, 2-bipyrimidine acceptor. The XB interactions in the solid state of 1/2, 2-dipyridine and 1/2, 2-bipyrimidine were confirmed by a series of characterization methods, such as thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) involving 19F NMR and solid-state 13C NMR. Organic field-effect transistors (OFETs) based on XB complexes 1/2, 2-dipyridine or 1/2, 2-bipyrimidine showed better device performance than that of devices based on pure 1, with the average electron mobility increased more than doubled (from 0.027 cm2 V-1 s-1 to 0.070 cm2 V-1 s-1).
Controlling microstructure and thin film morphology of organic semiconductors by supramolecular arrangement is critical to improving their device performance. To realize well-controlling supramolecular assembly, a core-expanded naphthalene diimides derivative (1) was designed and synthesized as an n-type organic semiconductor and also as a halogen bonding (XB) donor that could form complementary XBs with 2, 2-dipyridine or 2, 2-bipyrimidine acceptor. The XB interactions in the solid state of 1/2, 2-dipyridine and 1/2, 2-bipyrimidine were confirmed by a series of characterization methods, such as thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance (NMR) involving 19F NMR and solid-state 13C NMR. Organic field-effect transistors (OFETs) based on XB complexes 1/2, 2-dipyridine or 1/2, 2-bipyrimidine showed better device performance than that of devices based on pure 1, with the average electron mobility increased more than doubled (from 0.027 cm2 V-1 s-1 to 0.070 cm2 V-1 s-1).
2018, 29(3): 429-432
doi: 10.1016/j.cclet.2017.07.013
Abstract:
Work function plays a significant role in surface chemistry. Local work function provides the information of local dipole-dipole interaction and charge distribution between adsorbates and substrate, highlighting the local charge effect of the targeted spot which is normally smeared out in conventional average work function measurements. Chloroaluminum phthalocyanine (ClAlPc), an important optoelectronic molecule with a permanent dipole moment pointing from the Pc ring to the ending Cl atom, adsorbed on Au(111) in either Cl-up or Cl-down configuration. Scanning tunneling microscopy/spectroscopy measurements revealed that at the centers of Cl-up and Cl-down molecules, the local work functions changed oppositely with respect to the Au(111) substrate. At their Pc lobes, however, the local work functions unanimously increased due to charging effect of the indole lobes in the ClAlPc molecule.
Work function plays a significant role in surface chemistry. Local work function provides the information of local dipole-dipole interaction and charge distribution between adsorbates and substrate, highlighting the local charge effect of the targeted spot which is normally smeared out in conventional average work function measurements. Chloroaluminum phthalocyanine (ClAlPc), an important optoelectronic molecule with a permanent dipole moment pointing from the Pc ring to the ending Cl atom, adsorbed on Au(111) in either Cl-up or Cl-down configuration. Scanning tunneling microscopy/spectroscopy measurements revealed that at the centers of Cl-up and Cl-down molecules, the local work functions changed oppositely with respect to the Au(111) substrate. At their Pc lobes, however, the local work functions unanimously increased due to charging effect of the indole lobes in the ClAlPc molecule.
2018, 29(3): 433-436
doi: 10.1016/j.cclet.2017.08.017
Abstract:
Poly(vinyl alcohol)/montmorillonite aerogels with high thermal stability and flame retardancy were prepared with a facile heat treatment method, in which the poly(vinyl alcohol)/montmorillonite aerogels was first prepared by an eco-friendly freeze-drying method, following by a heat treatment process. The structure of the aerogels before and after heat treatment process was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The thermal stability of the aerogel treated for 3 h at 200℃ was improved significantly, which was accompanied by a slight decrease of mechanical property. Meanwhile, cone calorimetry (CC) test revealed that the flame-retardant performance of the heat treated aerogel was improved remarkably.
Poly(vinyl alcohol)/montmorillonite aerogels with high thermal stability and flame retardancy were prepared with a facile heat treatment method, in which the poly(vinyl alcohol)/montmorillonite aerogels was first prepared by an eco-friendly freeze-drying method, following by a heat treatment process. The structure of the aerogels before and after heat treatment process was characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The thermal stability of the aerogel treated for 3 h at 200℃ was improved significantly, which was accompanied by a slight decrease of mechanical property. Meanwhile, cone calorimetry (CC) test revealed that the flame-retardant performance of the heat treated aerogel was improved remarkably.
2018, 29(3): 437-440
doi: 10.1016/j.cclet.2017.08.028
Abstract:
Graphite-phase polymeric carbon nitride (CN) was reported to be a promising material in photoelectrochemical solar energy conversion. However, its high recombination rate of photogenerated carriers limits its potential applications. In this article, a heterojunction of CN and sulfur-doped CN (CNS) was constructed through a solution-based processing way. Interestingly, it was observed that the photocatalytic hydrogen production of the as-prepared composite was 32.6 times higher than that of bulk carbon nitride and 2.3 times higher than that of the composites by conventional impregnating method. This study opens a new avenue to construct heterojunction of CN for large-scale industrial applications in environmental remediation.
Graphite-phase polymeric carbon nitride (CN) was reported to be a promising material in photoelectrochemical solar energy conversion. However, its high recombination rate of photogenerated carriers limits its potential applications. In this article, a heterojunction of CN and sulfur-doped CN (CNS) was constructed through a solution-based processing way. Interestingly, it was observed that the photocatalytic hydrogen production of the as-prepared composite was 32.6 times higher than that of bulk carbon nitride and 2.3 times higher than that of the composites by conventional impregnating method. This study opens a new avenue to construct heterojunction of CN for large-scale industrial applications in environmental remediation.
2018, 29(3): 441-446
doi: 10.1016/j.cclet.2017.08.035
Abstract:
A series of novel title compounds 6a-6r and 7a-7c have been synthesized by Mannich reaction of the new triazole Schiff base intermidiates, substituted piperazine and formaldehyde under mild conditions in excellent yields. The crystal structure of compound 6i was determined to show a chair conformation of the piperazine ring and an (E)-configuration of the C=N double bond. The bioassay results indicated that most of the newly synthesized compounds exhibited excellent in vitro inhibitory activities and broader spectrum against several plant fungi, and were more effective than the control Triadimefon. Several compounds also displayed favourable in vivo antifungal activities. The relationships between the compound structures and various biological activities were discussed. Furthermore, the CoMFA calculation based on the antifungal activity data of compounds 6 against R. cerealis was carried out to establish a 3D-QSAR model, which revealed that steric and electrostatic fields were two most important factors for contributing the bioactivity of the compounds. The present work will provide significant information for guiding optimization of such new structures to develop novel agrochemicals with higher antifungal activities.
A series of novel title compounds 6a-6r and 7a-7c have been synthesized by Mannich reaction of the new triazole Schiff base intermidiates, substituted piperazine and formaldehyde under mild conditions in excellent yields. The crystal structure of compound 6i was determined to show a chair conformation of the piperazine ring and an (E)-configuration of the C=N double bond. The bioassay results indicated that most of the newly synthesized compounds exhibited excellent in vitro inhibitory activities and broader spectrum against several plant fungi, and were more effective than the control Triadimefon. Several compounds also displayed favourable in vivo antifungal activities. The relationships between the compound structures and various biological activities were discussed. Furthermore, the CoMFA calculation based on the antifungal activity data of compounds 6 against R. cerealis was carried out to establish a 3D-QSAR model, which revealed that steric and electrostatic fields were two most important factors for contributing the bioactivity of the compounds. The present work will provide significant information for guiding optimization of such new structures to develop novel agrochemicals with higher antifungal activities.
2018, 29(3): 447-450
doi: 10.1016/j.cclet.2017.09.030
Abstract:
One single crystal based on Th4+ and cucurbit[6 ]uril (CB6) in nitric acid aqueous solutions was synthesized by slow evaporation method. The single crystal was characterized by elemental analysis, single crystal X-ray diffraction, XRD, FT-IR and TGA. The complexed cation of Th4+ is a ten coordinated structure, in which the central thorium ion is coordinated by six monodentate water molecules and two bidentate nitrates. While CB6, as a second-sphere ligand, coordinates with the water molecules of[Th (NO3)2(H2O)6]2+ through the formation of hydrogen bonding. Two other nitrate ions act as the counter anions. Besides, there are two free water molecules in the crystal system. The formation of the Th4+-CB6 complex can contribute to the study of the coordination of CB6 and the extraction of Th4+ in HNO3 system
One single crystal based on Th4+ and cucurbit[
2018, 29(3): 451-455
doi: 10.1016/j.cclet.2017.09.016
Abstract:
To make photoinitiators (PI) to be polymeric and water-soluble is an effective approach to develop the high efficient photoinitiator systems with low-migration, low-toxic and environment-friend. We developed a series of novel amphiphilic hyperbranched polymeric photoinitiators (hPEA-TXs, and hPEABPs) by introducing thioxanthone (TX) or benzophenone (BP) moieties into the periphery of the hyperbranched poly(ether amine) (hPEA) comprised of the hydrophilic poly(ethylene oxide) (PEO) short chain and coinitiator amine moieties in the backbone. Compared with their water-soluble low-molecular weight analogues, the resulting hyperbranched polymeric photoinitiators hPEA101-TX, hPEA211-TX, hPEA101-BP and hPEA211-BP could be dissolved very well not only in many organic systems including acrylate monomers, but also in water with high solubility of 10 wt%. The photopolymerization kinetics of water-soluble monomer acrylamide (AM) and three hydrophobic multifunctional acrylate monomers initiated by these hyperbranched photoinitiators were investigated in detail by photo-differential scanning calorimetric (photo-DSC). Both hPEA-TXs and hPEA-BPs can initiate photopolymerization of AM as efficiently as their low-molecular weight analogues MGA-TX and MGA-BP, respectively. The final double bond conversion (DBC) of oil-soluble monomer hexanediol diacrylate (HDDA) photoinitiated by these hyperbranched photoinitiators can reach as high as 99%. Especially for photopolymerization of multifunctional monomers initiated by these hyperbranched polymeric photoinitiators, the final DBC of trimethylolpropane triacrylate (TMPTA) and pentaerythritol tetraacrylate (PETTA) can reach 80% and 60%, respectively, which is much higher than that of low-molecular weight photoinitiators.
To make photoinitiators (PI) to be polymeric and water-soluble is an effective approach to develop the high efficient photoinitiator systems with low-migration, low-toxic and environment-friend. We developed a series of novel amphiphilic hyperbranched polymeric photoinitiators (hPEA-TXs, and hPEABPs) by introducing thioxanthone (TX) or benzophenone (BP) moieties into the periphery of the hyperbranched poly(ether amine) (hPEA) comprised of the hydrophilic poly(ethylene oxide) (PEO) short chain and coinitiator amine moieties in the backbone. Compared with their water-soluble low-molecular weight analogues, the resulting hyperbranched polymeric photoinitiators hPEA101-TX, hPEA211-TX, hPEA101-BP and hPEA211-BP could be dissolved very well not only in many organic systems including acrylate monomers, but also in water with high solubility of 10 wt%. The photopolymerization kinetics of water-soluble monomer acrylamide (AM) and three hydrophobic multifunctional acrylate monomers initiated by these hyperbranched photoinitiators were investigated in detail by photo-differential scanning calorimetric (photo-DSC). Both hPEA-TXs and hPEA-BPs can initiate photopolymerization of AM as efficiently as their low-molecular weight analogues MGA-TX and MGA-BP, respectively. The final double bond conversion (DBC) of oil-soluble monomer hexanediol diacrylate (HDDA) photoinitiated by these hyperbranched photoinitiators can reach as high as 99%. Especially for photopolymerization of multifunctional monomers initiated by these hyperbranched polymeric photoinitiators, the final DBC of trimethylolpropane triacrylate (TMPTA) and pentaerythritol tetraacrylate (PETTA) can reach 80% and 60%, respectively, which is much higher than that of low-molecular weight photoinitiators.
2018, 29(3): 456-460
doi: 10.1016/j.cclet.2017.09.062
Abstract:
Although large amounts of engineered nanomaterials have been used for the arsenic removal, today there still remains several serious impediments to its further application, including consumption of expensive and pure salts, and only application for the removal of inorganic arsenic. In this work, we developed an eco-economic and facile electrochemical method to synthesize iron porous coordination polymers (FePCPs) for the simultaneous removal of inorganic and organic arsenic from natural water.
Although large amounts of engineered nanomaterials have been used for the arsenic removal, today there still remains several serious impediments to its further application, including consumption of expensive and pure salts, and only application for the removal of inorganic arsenic. In this work, we developed an eco-economic and facile electrochemical method to synthesize iron porous coordination polymers (FePCPs) for the simultaneous removal of inorganic and organic arsenic from natural water.
2018, 29(3): 461-463
doi: 10.1016/j.cclet.2017.09.055
Abstract:
Assembled protein-based substances are emerging and promising classes of materials that provide unique properties for various applications in biotechnology and nanotechnolegy. Self-assembly is an effective way to immobilize protein. In this study, DNAs-conjugated bovine serum albumin (BSA) assembled into fibers via DNA hybridization is demonstrated. The morphology of fibers was observed by optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM), and the assembly mechanism was then analysed and discussed. BSA molecules were first linked by DNA molecule and formed linear chains. These chains then were parallelly linked through additional DNA hybridization. Finally, several BSA chains further assembled into fibers by layering lamellae in a parallel manner. This work perhaps will provide a guide to the immobilization of enzyme, which could be applied to increase its catalytic efficiency in biomedicine and nanotechnology.
Assembled protein-based substances are emerging and promising classes of materials that provide unique properties for various applications in biotechnology and nanotechnolegy. Self-assembly is an effective way to immobilize protein. In this study, DNAs-conjugated bovine serum albumin (BSA) assembled into fibers via DNA hybridization is demonstrated. The morphology of fibers was observed by optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM), and the assembly mechanism was then analysed and discussed. BSA molecules were first linked by DNA molecule and formed linear chains. These chains then were parallelly linked through additional DNA hybridization. Finally, several BSA chains further assembled into fibers by layering lamellae in a parallel manner. This work perhaps will provide a guide to the immobilization of enzyme, which could be applied to increase its catalytic efficiency in biomedicine and nanotechnology.
2018, 29(3): 464-466
doi: 10.1016/j.cclet.2017.10.036
Abstract:
A mild and efficient methodology for the direct oxidative synthesis of nitriles from easily available alcohols and aqueous ammonia by employing CuCl/DABCO/4-HO-TEMPO as the catalysts is described. This protocol uses the air as a green oxidant and aqueous ammonia as the nitrogen source at room temperature. A variety of aryl, heterocyclic and allylic alcohols are smoothly converted into the corresponding nitriles in good to excellent yields.
A mild and efficient methodology for the direct oxidative synthesis of nitriles from easily available alcohols and aqueous ammonia by employing CuCl/DABCO/4-HO-TEMPO as the catalysts is described. This protocol uses the air as a green oxidant and aqueous ammonia as the nitrogen source at room temperature. A variety of aryl, heterocyclic and allylic alcohols are smoothly converted into the corresponding nitriles in good to excellent yields.
2018, 29(3): 467-470
doi: 10.1016/j.cclet.2017.10.009
Abstract:
One new sesquiterpene lactone, corialactone E (1), one new neolignan, coriarianeolignan A (2), together with three known apocarotenoids (3-5) and one known neolignan (6) have been isolated from a CHCl3 extract of the roots of Coriaria nepalensis. The structures including absolute configurations of 1-6 were elucidated through extensive NMR, HR-ESIMS, and CD data analysis. Structurally, compound 1 possessed novel variations in the structure, including the newly formed ether ring of C-3/O/C-9 and the lactone ring connecting C-13 and C-5. Compound 5 showed cytotoxic activity against SKOV3 (human ovarian cancer) cells with IC50 values of 4.67μmol/L. In vivo system, compound 3 showed anti-convulsant activity by 34% at the dose of 5 mg/kg.
One new sesquiterpene lactone, corialactone E (1), one new neolignan, coriarianeolignan A (2), together with three known apocarotenoids (3-5) and one known neolignan (6) have been isolated from a CHCl3 extract of the roots of Coriaria nepalensis. The structures including absolute configurations of 1-6 were elucidated through extensive NMR, HR-ESIMS, and CD data analysis. Structurally, compound 1 possessed novel variations in the structure, including the newly formed ether ring of C-3/O/C-9 and the lactone ring connecting C-13 and C-5. Compound 5 showed cytotoxic activity against SKOV3 (human ovarian cancer) cells with IC50 values of 4.67μmol/L. In vivo system, compound 3 showed anti-convulsant activity by 34% at the dose of 5 mg/kg.
2018, 29(3): 471-474
doi: 10.1016/j.cclet.2017.07.025
Abstract:
2, 7-Di(9, 9-dimethyl-9H-fluoren-1-yl)-9H-thioxanthen-9-one (DMBFTX) with thermally activated delayed fluorescence (TADF) was well designed and synthesized. The phosphorescent organic lightemitting device (PHOLED) based on this novel TADF host material displays a stable red phosphorescence region, a peak external quantum efficiency (EQE) value of 12.9% and a low EQE roll-off of 38.8% at a luminance of 10000 cd/m2, which is benefited from the reverse intersystem crossing (RISC) of TADF host and less populated triplet exitons. Notably, the red device based on the TADF host DMBFTX exhibits superior electroluminescence performance and reduced efficiency roll-off compared with the one hosted by commercially available host 1, 3-bis(9-carbazolyl)benzene (mCP), illustrating the high potential of employing the TADF host material with small energy gap to reduce efficiency roll-off in PHOLED.
2, 7-Di(9, 9-dimethyl-9H-fluoren-1-yl)-9H-thioxanthen-9-one (DMBFTX) with thermally activated delayed fluorescence (TADF) was well designed and synthesized. The phosphorescent organic lightemitting device (PHOLED) based on this novel TADF host material displays a stable red phosphorescence region, a peak external quantum efficiency (EQE) value of 12.9% and a low EQE roll-off of 38.8% at a luminance of 10000 cd/m2, which is benefited from the reverse intersystem crossing (RISC) of TADF host and less populated triplet exitons. Notably, the red device based on the TADF host DMBFTX exhibits superior electroluminescence performance and reduced efficiency roll-off compared with the one hosted by commercially available host 1, 3-bis(9-carbazolyl)benzene (mCP), illustrating the high potential of employing the TADF host material with small energy gap to reduce efficiency roll-off in PHOLED.
2018, 29(3): 501-504
doi: 10.1016/j.cclet.2017.08.014
Abstract:
We reported a kind of inorganic-organic hybrid supramolecular hydrogel with excellent anti-biofouling capability. The hydrogel was formed via ionic interaction between the negative-charged sodium polyacrylate (SPA) entwined clay nanosheets (CNS) and positive-charged polyhedral oligomeric silsesquioxane (POSS) core-based generation one (L-Arginine) dendrimer (POSS-R). Due to their strong ionic interaction, this kind of hydrogel exhibited a rapid gelation behavior which accomplished even at a low POSS-R concentration about 1% w/v. With the increase of POSS-R concentration, these hydrogels appeared more compact structure, accompanied by remarkable enhanced mechanical strength. In addition, these hydrogels demonstrated rapid thixotropic response and shape-memory capability, as well as good biocompatibility. More importantly, these hydrogels exhibited outstanding anti-biofouling property due to the inherent anti-biofouling capability of SPA. Overall, these findings demonstrated a novel sort of inorganic-organic hybrid supramolecular hydrogel with tunable mechanical strength and excellent anti-biofouling capability, which may have a broad application potential in tissue engineering.
We reported a kind of inorganic-organic hybrid supramolecular hydrogel with excellent anti-biofouling capability. The hydrogel was formed via ionic interaction between the negative-charged sodium polyacrylate (SPA) entwined clay nanosheets (CNS) and positive-charged polyhedral oligomeric silsesquioxane (POSS) core-based generation one (L-Arginine) dendrimer (POSS-R). Due to their strong ionic interaction, this kind of hydrogel exhibited a rapid gelation behavior which accomplished even at a low POSS-R concentration about 1% w/v. With the increase of POSS-R concentration, these hydrogels appeared more compact structure, accompanied by remarkable enhanced mechanical strength. In addition, these hydrogels demonstrated rapid thixotropic response and shape-memory capability, as well as good biocompatibility. More importantly, these hydrogels exhibited outstanding anti-biofouling property due to the inherent anti-biofouling capability of SPA. Overall, these findings demonstrated a novel sort of inorganic-organic hybrid supramolecular hydrogel with tunable mechanical strength and excellent anti-biofouling capability, which may have a broad application potential in tissue engineering.
2018, 29(3): 505-508
doi: 10.1016/j.cclet.2017.08.018
Abstract:
Fluorescent dye (YOYO-1) intercalated with single DNA molecules were investigated via bindingactivated localization microscopy (BALM) at sub-diffraction limit resolutions. Various dye-to-DNA base pair (bp) ratios were imaged using the blinking property of YOYO-1 dye under optimum BALM switching buffer conditions. Individual DNA molecules exhibited regular/irregular intercalating phenomena with respect to dye-to-DNA bp ratio. The acquired images were reconstructed into super-resolution images by applying a Gaussian fit to the centroid of the point spread function. The YOYO-1 intercalated with λ-DNA possessed a non-homogeneous region due to the different binding modes of YOYO-1 with λ-DNA. Each binding mode was imaged at the sub-diffraction limit super-resolution. The distance between homogenously localized intercalating dyes within the DNA molecules was measured to be 34 nm (n=10; dye:DNAbp=1:100) without photocleavage in 50 mmol/L β-mercaptoethylamine buffer. The results were similar to those of the theoretical values without photocleavage in the base pairs of single DNA molecules below the diffraction limit. The results paved the way for an in-depth microscopic analysis of molecular variation with single λ-DNA molecules. With this method, it should be possible to analyze the exact base pair breakdown during various stages of cell apoptosis.
Fluorescent dye (YOYO-1) intercalated with single DNA molecules were investigated via bindingactivated localization microscopy (BALM) at sub-diffraction limit resolutions. Various dye-to-DNA base pair (bp) ratios were imaged using the blinking property of YOYO-1 dye under optimum BALM switching buffer conditions. Individual DNA molecules exhibited regular/irregular intercalating phenomena with respect to dye-to-DNA bp ratio. The acquired images were reconstructed into super-resolution images by applying a Gaussian fit to the centroid of the point spread function. The YOYO-1 intercalated with λ-DNA possessed a non-homogeneous region due to the different binding modes of YOYO-1 with λ-DNA. Each binding mode was imaged at the sub-diffraction limit super-resolution. The distance between homogenously localized intercalating dyes within the DNA molecules was measured to be 34 nm (n=10; dye:DNAbp=1:100) without photocleavage in 50 mmol/L β-mercaptoethylamine buffer. The results were similar to those of the theoretical values without photocleavage in the base pairs of single DNA molecules below the diffraction limit. The results paved the way for an in-depth microscopic analysis of molecular variation with single λ-DNA molecules. With this method, it should be possible to analyze the exact base pair breakdown during various stages of cell apoptosis.
2018, 29(3): 509-512
doi: 10.1016/j.cclet.2017.08.012
Abstract:
Bisphenol A (BPA) was one of the environmental hormones that would cause endocrine and metabolic disorders in human or wildlife. This paper proposed a method to detect the trace amounts of BPA in water samples by fully utilizing the enrichment and resonance amplification functions of a new dual-functional membrane. In this work, gold nanoparticles (AuNPs) modified by 3-amino-5-mercapto-1, 2, 4-triazole (AMT) were embedded in nylon66 membrane to produce a dual-functional membrane which could carry out sample enrichment by capturing BPA molecules from water and achieve resonance amplification by connecting BPA to the surfaces of AuNPs. By designing an automatic sampler for large-volume enrichment, the SERS enhancement factor (EF) of the method was further improved to 1.2 ×105. The present method had been successfully applied to detect BPA in drinking water and environmental water by SERS with the detection limit of 0.012 μg/L. It had the potential for on-site detecting of BPA in various water samples.
Bisphenol A (BPA) was one of the environmental hormones that would cause endocrine and metabolic disorders in human or wildlife. This paper proposed a method to detect the trace amounts of BPA in water samples by fully utilizing the enrichment and resonance amplification functions of a new dual-functional membrane. In this work, gold nanoparticles (AuNPs) modified by 3-amino-5-mercapto-1, 2, 4-triazole (AMT) were embedded in nylon66 membrane to produce a dual-functional membrane which could carry out sample enrichment by capturing BPA molecules from water and achieve resonance amplification by connecting BPA to the surfaces of AuNPs. By designing an automatic sampler for large-volume enrichment, the SERS enhancement factor (EF) of the method was further improved to 1.2 ×105. The present method had been successfully applied to detect BPA in drinking water and environmental water by SERS with the detection limit of 0.012 μg/L. It had the potential for on-site detecting of BPA in various water samples.
2018, 29(3): 513-516
doi: 10.1016/j.cclet.2017.08.019
Abstract:
Conjugated polymers with bisindolylmaleimide (BIM) backbone are obtained by the condensation polymerization of methyl and octanyl N-substituted BIMs with 4, 4'-difluoro-diphenylsulfone and 4, 4'-difluoro-diphenylketone. The structures of polymers are confirmed by FTIR and NMR spectroscopy. The polymers exhibit both high glass transition temperatures (Tg > 175℃) and high decomposition temperatures (T5 > 395℃). Meanwhile, The UV-vis absorption and fluorescence spectra of the polymers are similar to the corresponding substituted BIMs. The quantum chemistry calculations indicate that the first excited states of polymers are mostly contributed by BIM structures.
Conjugated polymers with bisindolylmaleimide (BIM) backbone are obtained by the condensation polymerization of methyl and octanyl N-substituted BIMs with 4, 4'-difluoro-diphenylsulfone and 4, 4'-difluoro-diphenylketone. The structures of polymers are confirmed by FTIR and NMR spectroscopy. The polymers exhibit both high glass transition temperatures (Tg > 175℃) and high decomposition temperatures (T5 > 395℃). Meanwhile, The UV-vis absorption and fluorescence spectra of the polymers are similar to the corresponding substituted BIMs. The quantum chemistry calculations indicate that the first excited states of polymers are mostly contributed by BIM structures.
2018, 29(3): 517-520
doi: 10.1016/j.cclet.2017.08.048
Abstract:
Based on an umpolung strategy, a series of novel full substituted, optically active dihydrothiophenes, which contain several functional groups, such as amine, ester and oxime groups, were obtained via an efficient organocatalytic asymmetric a formal thio[3 + 2]-cyclization of acyclic thioamides with (E)-α-nitrostyrenes.
Based on an umpolung strategy, a series of novel full substituted, optically active dihydrothiophenes, which contain several functional groups, such as amine, ester and oxime groups, were obtained via an efficient organocatalytic asymmetric a formal thio[3 + 2]-cyclization of acyclic thioamides with (E)-α-nitrostyrenes.
2018, 29(3): 521-523
doi: 10.1016/j.cclet.2017.08.056
Abstract:
Restricted-access materials (RAMs) have found their broad application in sample pretreatment of bioanalysis. Boronate affinity (BA) adsorption is a very efficient and facile method for isolation and enrichment of cis-diol containing biomolecules which are a large important group compounds in biosystems. However, preparation of BA-RAMs are rarely reported to date. In this study, a novel BA-RAM with external surface comprised of hydrophilic bottlebrush polymers was prepared exploiting the excellent capability of the bottlebrush polymers for protein exclusion. A diblock copolymer poly(3-acrylamidophenylboronic acid)-block-poly(2-hydroxyethyl methacrylate) (PAAPBA-b-PHEMA) was first grafted from the silica surface via surface-initiated reversible addition-fragmentation chain transfer polymerization (SI-RAFT), and poly(N-isopropylacrylamide) (PNIPAAm) was then grafted from the PHEMA via surface-initiated atom transfer radical polymerization (SI-ATRP) to yield the BA-RAM. The BARAM exhibits high selectivity to cis-diol containing small molecules and has good capability to exclude proteins. Its practical application in bioanalysis was tested by pretreatment of serum sample for analysis of catecholamines with high recoveries and good precision. The preparation strategy for the BA-RAM is very versatile and is easy to be expanded to other modes of RAMs.
Restricted-access materials (RAMs) have found their broad application in sample pretreatment of bioanalysis. Boronate affinity (BA) adsorption is a very efficient and facile method for isolation and enrichment of cis-diol containing biomolecules which are a large important group compounds in biosystems. However, preparation of BA-RAMs are rarely reported to date. In this study, a novel BA-RAM with external surface comprised of hydrophilic bottlebrush polymers was prepared exploiting the excellent capability of the bottlebrush polymers for protein exclusion. A diblock copolymer poly(3-acrylamidophenylboronic acid)-block-poly(2-hydroxyethyl methacrylate) (PAAPBA-b-PHEMA) was first grafted from the silica surface via surface-initiated reversible addition-fragmentation chain transfer polymerization (SI-RAFT), and poly(N-isopropylacrylamide) (PNIPAAm) was then grafted from the PHEMA via surface-initiated atom transfer radical polymerization (SI-ATRP) to yield the BA-RAM. The BARAM exhibits high selectivity to cis-diol containing small molecules and has good capability to exclude proteins. Its practical application in bioanalysis was tested by pretreatment of serum sample for analysis of catecholamines with high recoveries and good precision. The preparation strategy for the BA-RAM is very versatile and is easy to be expanded to other modes of RAMs.
2018, 29(3): 524-526
doi: 10.1016/j.cclet.2017.09.001
Abstract:
The nucleophilic ring opening reaction of propargyl epoxides by amines based on a silver catalyst is presented. The reaction takes place under mild conditions and features a high regioselectivity to provide an effective method for the synthesis of 2-amino homopropargyl alcohols in moderate to high yields.
The nucleophilic ring opening reaction of propargyl epoxides by amines based on a silver catalyst is presented. The reaction takes place under mild conditions and features a high regioselectivity to provide an effective method for the synthesis of 2-amino homopropargyl alcohols in moderate to high yields.
2018, 29(3): 547-550
doi: 10.1016/j.cclet.2017.09.025
Abstract:
TiO2/EDTA-rich carbon composites (TiO2/EDTA-RC) have been successfully synthesized via a low temperature carbonization process. TiO2/EDTA-RC exhibits marked absorption of visible light and excellent photoreduction of Cr(Ⅵ) activity under visible light irradiation (λ > 420 nm). Due to the high carboxyl group content and strong coordination ability of EDTA, TiO2-EDTA complex can be easily fabricated between EDTA incorporated in carbon sheet and titanol group on the surface of TiO2. TiO2-EDTA complexes on the surface of TiO2/EDTA-RC, the LMCT complex, are responsible for the prominent photoreduction of Cr(Ⅵ) properties of TiO2/EDTA-RC under visible light irradiation. In addition, the unique structure of TiO2/EDTA-RC is also propitious to the visible-light photocatalytic reduction of Cr(Ⅵ). Carbon sheet of TiO2/EDTA-RC acts as a supporter. TiO2 nanoparticles and EDTA homogeneously disperse into the carbon sheet supporter and form the TiO2-EDTA complexes, which can avoid the aggregation of TiO2 nanoparticles in the aqueous solution and provide more photocatalytic reaction points for the reduction of Cr(Ⅵ).
TiO2/EDTA-rich carbon composites (TiO2/EDTA-RC) have been successfully synthesized via a low temperature carbonization process. TiO2/EDTA-RC exhibits marked absorption of visible light and excellent photoreduction of Cr(Ⅵ) activity under visible light irradiation (λ > 420 nm). Due to the high carboxyl group content and strong coordination ability of EDTA, TiO2-EDTA complex can be easily fabricated between EDTA incorporated in carbon sheet and titanol group on the surface of TiO2. TiO2-EDTA complexes on the surface of TiO2/EDTA-RC, the LMCT complex, are responsible for the prominent photoreduction of Cr(Ⅵ) properties of TiO2/EDTA-RC under visible light irradiation. In addition, the unique structure of TiO2/EDTA-RC is also propitious to the visible-light photocatalytic reduction of Cr(Ⅵ). Carbon sheet of TiO2/EDTA-RC acts as a supporter. TiO2 nanoparticles and EDTA homogeneously disperse into the carbon sheet supporter and form the TiO2-EDTA complexes, which can avoid the aggregation of TiO2 nanoparticles in the aqueous solution and provide more photocatalytic reaction points for the reduction of Cr(Ⅵ).
Positioning a fluorescent probe at the core of a glassy star polymer for detection of local dynamics
2018, 29(3): 374-380
doi: 10.1016/j.cclet.2017.07.010
Abstract:
Accessing local dynamics within a single macromolecule is the key to understand the physical origin of the viscoelasticity and especially the glass transition. In order to extract specific information on the dynamics of the branch point of a star polymer around its glass transition temperature, four-arm star poly (n-butyl methacrylate) with a fluorescent core was synthesized using perylene diimide as initiator and polymerization conducted via atom transfer radical polymerization. The process is found to be effective in positioning the fluorophore at the branch point with the fluorophore intact, which allows the successful application of single molecule fluorescence defocus imaging in examining the local sitesensitive dynamics. The power spectra of rotation trajectories, the population of rotating fluorophores as well as the distribution of angular displacement were used to revel the difference in local dynamics between branch point and the arm's end. It is discovered that the local dynamics at the core of the star polymer is much less activated than that at the arm's end. The results demonstrate the strong effect dues to the topological constrain at the branch point and the more free space at the arm's end.
Accessing local dynamics within a single macromolecule is the key to understand the physical origin of the viscoelasticity and especially the glass transition. In order to extract specific information on the dynamics of the branch point of a star polymer around its glass transition temperature, four-arm star poly (n-butyl methacrylate) with a fluorescent core was synthesized using perylene diimide as initiator and polymerization conducted via atom transfer radical polymerization. The process is found to be effective in positioning the fluorophore at the branch point with the fluorophore intact, which allows the successful application of single molecule fluorescence defocus imaging in examining the local sitesensitive dynamics. The power spectra of rotation trajectories, the population of rotating fluorophores as well as the distribution of angular displacement were used to revel the difference in local dynamics between branch point and the arm's end. It is discovered that the local dynamics at the core of the star polymer is much less activated than that at the arm's end. The results demonstrate the strong effect dues to the topological constrain at the branch point and the more free space at the arm's end.
2018, 29(3): 381-384
doi: 10.1016/j.cclet.2017.11.018
Abstract:
Recently, the fused-ring based low band gap (LBG) small molecule acceptors (SMAs) have emerged as efficient nonfullerene acceptors. So far, these LBG SMAs are mainly designed with IC (2-methylene-(3-(1, 1-dicyanomethylene)indanone)) or its analogs, the benzo-type electron-accepting (A) units. Compared to benzene, thiophene is less aromatic and thus the thiophene-involving semiconducting molecule has more quinoidal character, which effectively reduces the energy gap between the highest occupied molecular orbit (HOMO) and the lowest unoccupied molecular orbit (LUMO). Herein, we show that replacing the IC units in ITIC with the CT (cyclopenta[c]thiophen-4-one-5-methylene-6-(1, 1-dicyanomethylene)), a thiophene-fused A unit, the quinoidal character is enhanced from 0.0353 on ITIC to 0.0349 on ITCT, the CT-ended SMA. The increase in the quinoidal character reduces the optical band gap and enhances the near IR absorptivity. When blended with the wide band gap (WBG) polymer donor, PBDB-T, an average power conversion efficiency of 10.99% is obtained with a short-circuit current-density (Jsc) of 17.88 mA/cm2 and a fill-factor (FF) of 0.723. For comparisons, the Jsc is of 16.92 mA/cm2, FF is of 0.655 and PCE is of 9.94% obtained from the ITIC:PBDB-T device. This case indicates that the replacement of the benzene ring on the IC unit with a more polarizable five-member ring such as thiophene is an effective way to enhance the absorption of the near IR solar photons towards designing high-performance nonfullerene polymer solar cells.
Recently, the fused-ring based low band gap (LBG) small molecule acceptors (SMAs) have emerged as efficient nonfullerene acceptors. So far, these LBG SMAs are mainly designed with IC (2-methylene-(3-(1, 1-dicyanomethylene)indanone)) or its analogs, the benzo-type electron-accepting (A) units. Compared to benzene, thiophene is less aromatic and thus the thiophene-involving semiconducting molecule has more quinoidal character, which effectively reduces the energy gap between the highest occupied molecular orbit (HOMO) and the lowest unoccupied molecular orbit (LUMO). Herein, we show that replacing the IC units in ITIC with the CT (cyclopenta[c]thiophen-4-one-5-methylene-6-(1, 1-dicyanomethylene)), a thiophene-fused A unit, the quinoidal character is enhanced from 0.0353 on ITIC to 0.0349 on ITCT, the CT-ended SMA. The increase in the quinoidal character reduces the optical band gap and enhances the near IR absorptivity. When blended with the wide band gap (WBG) polymer donor, PBDB-T, an average power conversion efficiency of 10.99% is obtained with a short-circuit current-density (Jsc) of 17.88 mA/cm2 and a fill-factor (FF) of 0.723. For comparisons, the Jsc is of 16.92 mA/cm2, FF is of 0.655 and PCE is of 9.94% obtained from the ITIC:PBDB-T device. This case indicates that the replacement of the benzene ring on the IC unit with a more polarizable five-member ring such as thiophene is an effective way to enhance the absorption of the near IR solar photons towards designing high-performance nonfullerene polymer solar cells.
2018, 29(3): 385-389
doi: 10.1016/j.cclet.2017.11.014
Abstract:
A N, N, N', N'-tetraphenylbenzidine-bridged bis(2, 2'-bipyridine) ligand and corresponding diruthenium complexes were synthesized and characterized. They show rich multistep redox processes due to the stepwise oxidations of the amine units and ruthenium components. Their absorption and emission spectral changes in response to electrochemical stimulus were examined by spectroelectrochemical measurements. DFT and TDDFT calculations were performed to complement the experimental results.
A N, N, N', N'-tetraphenylbenzidine-bridged bis(2, 2'-bipyridine) ligand and corresponding diruthenium complexes were synthesized and characterized. They show rich multistep redox processes due to the stepwise oxidations of the amine units and ruthenium components. Their absorption and emission spectral changes in response to electrochemical stimulus were examined by spectroelectrochemical measurements. DFT and TDDFT calculations were performed to complement the experimental results.
2018, 29(3): 390-394
doi: 10.1016/j.cclet.2018.01.006
Abstract:
Polypropylene microporous membranes are typical hydrophobic separation membranes, but the high hydrophobicity and lack of functionality easily cause bacterial adhesion, thus inducing membrane pollution. Poly(AMS-co-DMAEMA) (PAD) was designed and synthesized by copolymerization of α-methyl styrene (AMS) and functional monomer 2-(dimethylamino)ethyl methacrylate (DMAEMA), and then grafted onto PP chains by melt blending. Microporous membranes of blended PP containing different contents of PAD are made by casting and stretching, and the polycation microporous membrane is then obtained via quaternization. The permeability and porosity of the microporous membrane achieve the best when the grafting efficiency reaches 42.16%, and the hydrophilicity of the microporous membrane is improved. The results show that the modified membranes fabricated in this method have good antibacterial properties.
Polypropylene microporous membranes are typical hydrophobic separation membranes, but the high hydrophobicity and lack of functionality easily cause bacterial adhesion, thus inducing membrane pollution. Poly(AMS-co-DMAEMA) (PAD) was designed and synthesized by copolymerization of α-methyl styrene (AMS) and functional monomer 2-(dimethylamino)ethyl methacrylate (DMAEMA), and then grafted onto PP chains by melt blending. Microporous membranes of blended PP containing different contents of PAD are made by casting and stretching, and the polycation microporous membrane is then obtained via quaternization. The permeability and porosity of the microporous membrane achieve the best when the grafting efficiency reaches 42.16%, and the hydrophilicity of the microporous membrane is improved. The results show that the modified membranes fabricated in this method have good antibacterial properties.
2018, 29(3): 395-398
doi: 10.1016/j.cclet.2018.01.023
Abstract:
Bioactive glass-chitosan-alginate hybrid scaffolds (BG-C-A scaffolds) were fabricated using BG sol as a dual function additive, which behaves as both bioactive inorganic phase to confer the bioactivity and cross-linker to improve the structural stability and mechanical properties. The microstructure, physicochemical and mechanical properties, in vitro bioactivity and cellular biocompatibility of the scaffolds were investigated. The results indicated that BG component was successfully incorporated into the BG-C-A scaffolds through a facile BG sol-immersing method and the original interconnected microstructure could be well preserved. The obtained BG-C-A scaffolds showed improved mechanical properties and structural stability as compared to C-A scaffolds. At the same time, they presented excellent in vitro bioactivity and cellular compatibility. All these results demonstrated that these BG-C-A scaffolds have promising potential for tissue engineering.
Bioactive glass-chitosan-alginate hybrid scaffolds (BG-C-A scaffolds) were fabricated using BG sol as a dual function additive, which behaves as both bioactive inorganic phase to confer the bioactivity and cross-linker to improve the structural stability and mechanical properties. The microstructure, physicochemical and mechanical properties, in vitro bioactivity and cellular biocompatibility of the scaffolds were investigated. The results indicated that BG component was successfully incorporated into the BG-C-A scaffolds through a facile BG sol-immersing method and the original interconnected microstructure could be well preserved. The obtained BG-C-A scaffolds showed improved mechanical properties and structural stability as compared to C-A scaffolds. At the same time, they presented excellent in vitro bioactivity and cellular compatibility. All these results demonstrated that these BG-C-A scaffolds have promising potential for tissue engineering.
2018, 29(3): 475-478
doi: 10.1016/j.cclet.2017.09.020
Abstract:
PtSnNa/γ-Al2O3 catalyst is widely used in the dehydrogenation of light alkane. This paper reports a new fabrication method of the catalyst. In the work, γ-Al2O3, SnCl4 and NaCl were ball milled to upload Sn and Na+ onto the support instead of the conventionally used immersion method. The subsequent baking procedures frimly fixed Sn onto the support, which could disperse Pt introduced by immersion. The effects of Sn and Na+ additives on the catalytic performance of PtSnNa/γ-Al2O3 catalyst were investigated. It was found that the appropriate molar ratio of Sn/Pt was 6:1 while the favorable weight percentage of Na+ was 0.90%. Compared with the reaction catalyzed by the industrially employed PtSnNa/γ-Al2O3 catalyst, the conversion of propane and the selectivity of propylene had been greatly improved, which were 26.97% and 99.18% respectively after 12 h reaction.
PtSnNa/γ-Al2O3 catalyst is widely used in the dehydrogenation of light alkane. This paper reports a new fabrication method of the catalyst. In the work, γ-Al2O3, SnCl4 and NaCl were ball milled to upload Sn and Na+ onto the support instead of the conventionally used immersion method. The subsequent baking procedures frimly fixed Sn onto the support, which could disperse Pt introduced by immersion. The effects of Sn and Na+ additives on the catalytic performance of PtSnNa/γ-Al2O3 catalyst were investigated. It was found that the appropriate molar ratio of Sn/Pt was 6:1 while the favorable weight percentage of Na+ was 0.90%. Compared with the reaction catalyzed by the industrially employed PtSnNa/γ-Al2O3 catalyst, the conversion of propane and the selectivity of propylene had been greatly improved, which were 26.97% and 99.18% respectively after 12 h reaction.
2018, 29(3): 479-481
doi: 10.1016/j.cclet.2017.06.023
Abstract:
In the presence of molecular iodine, the reaction of alkenes with diselenides proceeds efficiently under air and at room temperature in mixed solvent MeCN/H2O, which affording β-hydroxy selenides with high regioselectivity and in good to excellent yields. This iodine-mediated vicinal difunctionalization of alkenes requires mild reaction conditions and is a simple procedure, which extends the synthetic application of molecular iodine in organic synthesis.
In the presence of molecular iodine, the reaction of alkenes with diselenides proceeds efficiently under air and at room temperature in mixed solvent MeCN/H2O, which affording β-hydroxy selenides with high regioselectivity and in good to excellent yields. This iodine-mediated vicinal difunctionalization of alkenes requires mild reaction conditions and is a simple procedure, which extends the synthetic application of molecular iodine in organic synthesis.
2018, 29(3): 482-484
doi: 10.1016/j.cclet.2017.07.031
Abstract:
Herein, we report the effects of doped K and Al on the carbon dioxide (CO2) adsorption performance of the Li4SiO4-based adsorbents. The CO2 adsorption capacity of 0.8 wt% K and 1.5 wt% Al doped Li4SiO4 is~2.2 times and~1.3 times higher than that of the pristine Li4SiO4 at 500 and 600℃, respectively. The kinetic study further indicated that the reaction rates of the lithium diffusion process is greatly improved by K and Al doping, and the lithium diffusion rate of 0.8 wt% K and 1.5 wt% Al doped Li4SiO4 is~2 times higher than that of the pristine Li4SiO4 at 575-650℃. K and Al doping increases the adsorption capacity of Li4SiO4-based adsorbents, and widens its effective adsorption temperature range
Herein, we report the effects of doped K and Al on the carbon dioxide (CO2) adsorption performance of the Li4SiO4-based adsorbents. The CO2 adsorption capacity of 0.8 wt% K and 1.5 wt% Al doped Li4SiO4 is~2.2 times and~1.3 times higher than that of the pristine Li4SiO4 at 500 and 600℃, respectively. The kinetic study further indicated that the reaction rates of the lithium diffusion process is greatly improved by K and Al doping, and the lithium diffusion rate of 0.8 wt% K and 1.5 wt% Al doped Li4SiO4 is~2 times higher than that of the pristine Li4SiO4 at 575-650℃. K and Al doping increases the adsorption capacity of Li4SiO4-based adsorbents, and widens its effective adsorption temperature range
2018, 29(3): 485-488
doi: 10.1016/j.cclet.2017.07.003
Abstract:
A chirality induced helicity method has been developed to modulate the peptide's biophysical and biochemical properties. We report herein a novel approach for reversibly switching the conformation of short constraint α-helical peptides through alkylation of the in-tether thioether and dealkylation of the chiral sulfonium. This traceless redox sensitive tagging strategy broadened our scope of CIH (chirality induced helicity) strategy and provided a valuable approach to functionalize the peptide tether.
A chirality induced helicity method has been developed to modulate the peptide's biophysical and biochemical properties. We report herein a novel approach for reversibly switching the conformation of short constraint α-helical peptides through alkylation of the in-tether thioether and dealkylation of the chiral sulfonium. This traceless redox sensitive tagging strategy broadened our scope of CIH (chirality induced helicity) strategy and provided a valuable approach to functionalize the peptide tether.
2018, 29(3): 489-492
doi: 10.1016/j.cclet.2017.07.023
Abstract:
In this research, the flame retardancy of neat alginate fiber, flame retardant viscose fiber (FRV) and alginate/FRV (50/50) blending fibers were investigated by vertical burning and cone calorimeter tests. The vertical burning test showed that the afterflame time of alginate fiber was 0 s, but alginate presented serious smoldering behavior with the afterglow time of 605 s and damaged length of 85 mm, while the afterglow time of FRV was 0 s. When the FRV was incorporated into alginate with the weight ratio of 50/50, the afterglow time and damaged length were significantly reduced to 85 s and 35 mm, indicating the smoldering of alginate can be effectively decreased. The morphology and chemical structure of the alginate residual demonstrated that it was seriously destroyed during smoldering process, which was ascribed to its relative low initial thermal degradation temperature. Based on the thermal properties analysis, alginate and FRV fibers shared the concurrence of rapid degradation in the same temperature region of 250-300℃, through which, the compact and stable char formed by FRV can prevent the heat transmission and suppress the smoldering of alginate. Further, the cone calorimeter results demonstrated that the time to ignition (TTI) significantly increased and peak heat release rate (PHRR) decreased for alginate/FRV (50/50) compared with FRV. With this research, a new method to overcome the smoldering of alginate was proposed by blending with FRV
In this research, the flame retardancy of neat alginate fiber, flame retardant viscose fiber (FRV) and alginate/FRV (50/50) blending fibers were investigated by vertical burning and cone calorimeter tests. The vertical burning test showed that the afterflame time of alginate fiber was 0 s, but alginate presented serious smoldering behavior with the afterglow time of 605 s and damaged length of 85 mm, while the afterglow time of FRV was 0 s. When the FRV was incorporated into alginate with the weight ratio of 50/50, the afterglow time and damaged length were significantly reduced to 85 s and 35 mm, indicating the smoldering of alginate can be effectively decreased. The morphology and chemical structure of the alginate residual demonstrated that it was seriously destroyed during smoldering process, which was ascribed to its relative low initial thermal degradation temperature. Based on the thermal properties analysis, alginate and FRV fibers shared the concurrence of rapid degradation in the same temperature region of 250-300℃, through which, the compact and stable char formed by FRV can prevent the heat transmission and suppress the smoldering of alginate. Further, the cone calorimeter results demonstrated that the time to ignition (TTI) significantly increased and peak heat release rate (PHRR) decreased for alginate/FRV (50/50) compared with FRV. With this research, a new method to overcome the smoldering of alginate was proposed by blending with FRV
2018, 29(3): 493-496
doi: 10.1016/j.cclet.2017.08.004
Abstract:
Four novel palladium(Ⅱ) complexes coordinated by phosphorus atoms from both 3, 5-disubstituted-1H-1, 2, 4-diazaphospholes in monodentate fashion were developed as efficient catalyst for the MizorokiHeck reaction of aryl halides with electron-deficient olefins. The coupling reaction of aryl halide bearig different functional groups with olefin derivatives took place and the corresponding products were isolated in good to excellent yields under optimal conditions. The procedure exhibits good functional group tolerance and wide substrate scope. This Mizoroki-Heck reaction was further achieved using Pd(OAc)2 and 3, 5-di-isopropyl-1H-1, 2, 4-diazaphospholes as combined catalyst, which provide the convenient and alternative method in organic synthesis
Four novel palladium(Ⅱ) complexes coordinated by phosphorus atoms from both 3, 5-disubstituted-1H-1, 2, 4-diazaphospholes in monodentate fashion were developed as efficient catalyst for the MizorokiHeck reaction of aryl halides with electron-deficient olefins. The coupling reaction of aryl halide bearig different functional groups with olefin derivatives took place and the corresponding products were isolated in good to excellent yields under optimal conditions. The procedure exhibits good functional group tolerance and wide substrate scope. This Mizoroki-Heck reaction was further achieved using Pd(OAc)2 and 3, 5-di-isopropyl-1H-1, 2, 4-diazaphospholes as combined catalyst, which provide the convenient and alternative method in organic synthesis
2018, 29(3): 497-500
doi: 10.1016/j.cclet.2017.08.008
Abstract:
Aggregation-induced emission-active 4-(3, 4, 5-bis(octyloxy)phenyl-9-anthracene acylhydrazone (AHPT8) has been designed and synthesized, and the photo-responsive properties of organogel and xerogel irradiated by visible light were investigated systematically. AHP-T8 can form thermo-reversible gels in some of the tested solvents. The enhanced fluorescence emission has been observed after gelation although the dilute solution of AHP-T8 was almost non-fluorescent. When the organogel was exposed under visible light, the gel-sol phase transition occurred, and the corresponding morphology, fluorescence intensity, intermolecular hydrogen bonding and the structure all changed. In addition, the xerogel is more sensitive to visible light than that of organogel. The photoresponsive behaviour of AHP-T8 upon irradiation by visible light was demonstrated to be due to the E-Z isomerizations of -C=N-group, rather than the photodimerization of anthracene groups
Aggregation-induced emission-active 4-(3, 4, 5-bis(octyloxy)phenyl-9-anthracene acylhydrazone (AHPT8) has been designed and synthesized, and the photo-responsive properties of organogel and xerogel irradiated by visible light were investigated systematically. AHP-T8 can form thermo-reversible gels in some of the tested solvents. The enhanced fluorescence emission has been observed after gelation although the dilute solution of AHP-T8 was almost non-fluorescent. When the organogel was exposed under visible light, the gel-sol phase transition occurred, and the corresponding morphology, fluorescence intensity, intermolecular hydrogen bonding and the structure all changed. In addition, the xerogel is more sensitive to visible light than that of organogel. The photoresponsive behaviour of AHP-T8 upon irradiation by visible light was demonstrated to be due to the E-Z isomerizations of -C=N-group, rather than the photodimerization of anthracene groups
2018, 29(3): 527-530
doi: 10.1016/j.cclet.2017.09.007
Abstract:
In this study, Fe-doped TiO2/SiO2 (Fe@TS) nanofibrous membranes with molecular imprinted modification, were fabricated by a combination of sol-gel process, electrospinning, calcination and liquid phase deposition techniques. The precursor sol was prepared from one-pot condensation of poly (vinylpyrrolidone), ferric chloride hexahydrate, tetraethyl orthosilicate and titanium n-butoxide in the mixture solvents of N, N-dimethylformamide and ethyl alcohol. Fibrous membrane wasthen fabricated by electrospinning, followed by calcination to form the Fe@TS composite. The physicochemical properties of Fe@TS were characterized. Thereafter, 4-nitrophenol (4NP) was used as the template to deposit onto nanofibrous Fe@TS membranes, with a thin layer of molecular imprinted polymer in liquid phase. The photodegradation capabilities of 4NP and methyl orange wereexamined in both single and binary systems. The results demonstrated that molecular imprinted Fe@TS membranes exhibited excellent selectivity for photodegradation of 4NP.
In this study, Fe-doped TiO2/SiO2 (Fe@TS) nanofibrous membranes with molecular imprinted modification, were fabricated by a combination of sol-gel process, electrospinning, calcination and liquid phase deposition techniques. The precursor sol was prepared from one-pot condensation of poly (vinylpyrrolidone), ferric chloride hexahydrate, tetraethyl orthosilicate and titanium n-butoxide in the mixture solvents of N, N-dimethylformamide and ethyl alcohol. Fibrous membrane wasthen fabricated by electrospinning, followed by calcination to form the Fe@TS composite. The physicochemical properties of Fe@TS were characterized. Thereafter, 4-nitrophenol (4NP) was used as the template to deposit onto nanofibrous Fe@TS membranes, with a thin layer of molecular imprinted polymer in liquid phase. The photodegradation capabilities of 4NP and methyl orange wereexamined in both single and binary systems. The results demonstrated that molecular imprinted Fe@TS membranes exhibited excellent selectivity for photodegradation of 4NP.
2018, 29(3): 531-534
doi: 10.1016/j.cclet.2017.09.010
Abstract:
G-quadruplex ligands have been accepted as potential therapeutic agents for anticancer treatment. Thioflavin T (ThT), a highly selective G-quadruplex ligand, can bind G-quadruplex with a fluorescent light-up signal change and high specificity against DNA duplex. However, there are still different opinions that ThT induces/stabilizes G-quadruplex foldings/topologies in human telomere sequence. Here, a sensitive single-molecule nanopore technology was utilized to analyze the interactions between human telomeric DNA (Tel DNA) and ThT. Both translocation time and current blockade were measured to investigate the translocation behaviors. Furthermore, the effects of metal ion (K+ and Na+) and pH on the translocation behaviors were studied. Based on the single-molecule level analysis, there are some conclusions:(1) In the electrolyte solution containing 50 mmol/L KCl and 450 mmol/L NaCl, ThT can bind strongly with Tel DNA but nearly does not change the G-quadruplex form; (2) In the presence of high concentration K+, the ThT binding induces the structural change of hybrid G-quadruplex into antiparallel topology with an enhanced structural stability; (3) In either alkaline or acidic buffer, G-quadruplex form will change in certain degree. All above conclusions are helpful to deeply understand the interaction behaviors between Tel DNA and ThT. This nanopore platform, investigating G-quadruplex ligands at the single-molecule level, has great potential for the design of new drugs and sensors.
G-quadruplex ligands have been accepted as potential therapeutic agents for anticancer treatment. Thioflavin T (ThT), a highly selective G-quadruplex ligand, can bind G-quadruplex with a fluorescent light-up signal change and high specificity against DNA duplex. However, there are still different opinions that ThT induces/stabilizes G-quadruplex foldings/topologies in human telomere sequence. Here, a sensitive single-molecule nanopore technology was utilized to analyze the interactions between human telomeric DNA (Tel DNA) and ThT. Both translocation time and current blockade were measured to investigate the translocation behaviors. Furthermore, the effects of metal ion (K+ and Na+) and pH on the translocation behaviors were studied. Based on the single-molecule level analysis, there are some conclusions:(1) In the electrolyte solution containing 50 mmol/L KCl and 450 mmol/L NaCl, ThT can bind strongly with Tel DNA but nearly does not change the G-quadruplex form; (2) In the presence of high concentration K+, the ThT binding induces the structural change of hybrid G-quadruplex into antiparallel topology with an enhanced structural stability; (3) In either alkaline or acidic buffer, G-quadruplex form will change in certain degree. All above conclusions are helpful to deeply understand the interaction behaviors between Tel DNA and ThT. This nanopore platform, investigating G-quadruplex ligands at the single-molecule level, has great potential for the design of new drugs and sensors.
2018, 29(3): 535-537
doi: 10.1016/j.cclet.2017.09.006
Abstract:
A new epipolythiodioxopiperazine (ETP), asperterzine (1), along with two known analogs, bisdethiobis (methylthio)-acetylaranotin (2) and bisdethiobis(methylthio)-acetylapoaranotin (3), was isolated from the plant endophytic fungus Aspergillus terreus PR-P-2. The structure elucidation of 1 was accomplished by a combination of spectral methods and electronic circular dichroism (ECD) spectrum. Asperterzine (1) was a symmetric aromatized ETP found as a natural product for the first time. Compounds 2 and 3 showed strong cytotoxicity against HL-60 cell line. The putative biosynthetic pathway of 1 was also detailed in the text.
A new epipolythiodioxopiperazine (ETP), asperterzine (1), along with two known analogs, bisdethiobis (methylthio)-acetylaranotin (2) and bisdethiobis(methylthio)-acetylapoaranotin (3), was isolated from the plant endophytic fungus Aspergillus terreus PR-P-2. The structure elucidation of 1 was accomplished by a combination of spectral methods and electronic circular dichroism (ECD) spectrum. Asperterzine (1) was a symmetric aromatized ETP found as a natural product for the first time. Compounds 2 and 3 showed strong cytotoxicity against HL-60 cell line. The putative biosynthetic pathway of 1 was also detailed in the text.
2018, 29(3): 538-542
doi: 10.1016/j.cclet.2017.09.018
Abstract:
The hexagonal (h)-WO3-Cr2O3 nanocomposites with different W/Cr molar ratio of 4:1, 10:1 and 40:1 were prepared by a facile two-step hydrothermal method, and its gas sensing properties were investigated under optimum working temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) were used to characterize the morphology, microstructure and crystallinity of the as-synthesized samples. The hexagonal WO3 nanorods show a better crystallinity than Cr2O3 nanoparticles. When the molar ratio of W/Cr is 10:1, the hexagonal WO3-Cr2O3 nanocomposite shows obvious selectivity toward 2-butanone at 205¦ compared with other typical reducing gases, and the response value to 100 ppm 2-butanone can reach 5.6. However, there is no selectivity toward 2-butanone when the Cr/W molar ratio is 1:4 and 1:40. Furthermore, hexagonal WO3-Cr2O3 nanocomposites have a short response and recovery time to 5 ppm 2-butanone, which is 10 s and 80 s, respectively. The measured results indicate that hexagonal WO3-Cr2O3 nanocomposite is a potential gas sensing material for monitoring volatile organic compounds (VOCs).
The hexagonal (h)-WO3-Cr2O3 nanocomposites with different W/Cr molar ratio of 4:1, 10:1 and 40:1 were prepared by a facile two-step hydrothermal method, and its gas sensing properties were investigated under optimum working temperature. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) were used to characterize the morphology, microstructure and crystallinity of the as-synthesized samples. The hexagonal WO3 nanorods show a better crystallinity than Cr2O3 nanoparticles. When the molar ratio of W/Cr is 10:1, the hexagonal WO3-Cr2O3 nanocomposite shows obvious selectivity toward 2-butanone at 205¦ compared with other typical reducing gases, and the response value to 100 ppm 2-butanone can reach 5.6. However, there is no selectivity toward 2-butanone when the Cr/W molar ratio is 1:4 and 1:40. Furthermore, hexagonal WO3-Cr2O3 nanocomposites have a short response and recovery time to 5 ppm 2-butanone, which is 10 s and 80 s, respectively. The measured results indicate that hexagonal WO3-Cr2O3 nanocomposite is a potential gas sensing material for monitoring volatile organic compounds (VOCs).
2018, 29(3): 543-546
doi: 10.1016/j.cclet.2017.09.022
Abstract:
We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes (g-CNN) by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.
We investigated the thickness effect on the photophysics and charge carrier kinetics of graphitic carbon nitride nanoflakes (g-CNN) by using ultraviolet visible diffuse reflectance spectroscopy, atomic force microscopy, femtosecond transient absorption spectroscopy, and picosecond time-correlated single photon counting measurement. For the first time, we found that g-CNN displays a layer-dependent indirect bandgap and layer-dependent charge carrier kinetics.
