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2019 Volume 30 Issue 3
2019, 30(3): 533-540
doi: 10.1016/j.cclet.2018.10.010
Abstract:
Melanin nanoparticles (MNPs) is a kind of natural nanomaterial, not only retain the inherent characteristics of melanin (metal ion chelation, photothermal conversion property, etc.) but also can exhibit more excellent properties, such as high dispersion stability, good biocompatibility and biodegradability. Furthermore, these performances can be enhanced to target the specific sites and treat diseases by the surface modification or combination with functional substance. All these advantages of MNPs made it an ideal platform for developing biomedical applications. In this paper, the MNPs preparation methods were summarized first. Biomedical applications of MNPs were also reviewed, including molecular imaging (magnetic resonance, positron emission tomography, and photoacoustic imaging) and treatment of diseases (drug delivery, photothermal therapy, antioxidant therapy, and iron overload therapy). Further development and prospects of MNPs for practice in biology or medicine were also discussed.
Melanin nanoparticles (MNPs) is a kind of natural nanomaterial, not only retain the inherent characteristics of melanin (metal ion chelation, photothermal conversion property, etc.) but also can exhibit more excellent properties, such as high dispersion stability, good biocompatibility and biodegradability. Furthermore, these performances can be enhanced to target the specific sites and treat diseases by the surface modification or combination with functional substance. All these advantages of MNPs made it an ideal platform for developing biomedical applications. In this paper, the MNPs preparation methods were summarized first. Biomedical applications of MNPs were also reviewed, including molecular imaging (magnetic resonance, positron emission tomography, and photoacoustic imaging) and treatment of diseases (drug delivery, photothermal therapy, antioxidant therapy, and iron overload therapy). Further development and prospects of MNPs for practice in biology or medicine were also discussed.
2019, 30(3): 541-544
doi: 10.1016/j.cclet.2018.11.017
Abstract:
In this work, we designed a facile and promising strategy for fluorescence determination of S1 endonuclease activity and inhibition based on fluorescence resonance energy transfer (FRET) between positively Ag nanorods (AgNRs) and negatively-charged ROX-labeled sing-stranded DNA (ROX-ssDNA). In the absence of S1 endonuclease, the fluorescence signal of the ROX-ssDNA was efficiently quenched when the ROX-ssDNA was adsorbed on the surface of AgNRs via strong electrostatic interaction. However, upon addition of different concentration of S1 endonuclease, the fluorescence was gradually restored owing to the reduction of FRET efficiency caused by S1 endonuclease specific cleavage ROX-ssDNA into short fragments, which reduced the electrostatic interaction between AgNRs and short oligonucleotide fragment. This assay strategy exhibited a high sensitivity and excellent specificity for S1 endonuclease with a detection limit of 0.004 U/mL and a dynamic concentration range from 0.01 U/mL to 5.0 U/mL. In addition, the capabilities for screening of S1 endonuclease inhibitors and S1 endonuclease detection from complex biological matrixes were also verified.
In this work, we designed a facile and promising strategy for fluorescence determination of S1 endonuclease activity and inhibition based on fluorescence resonance energy transfer (FRET) between positively Ag nanorods (AgNRs) and negatively-charged ROX-labeled sing-stranded DNA (ROX-ssDNA). In the absence of S1 endonuclease, the fluorescence signal of the ROX-ssDNA was efficiently quenched when the ROX-ssDNA was adsorbed on the surface of AgNRs via strong electrostatic interaction. However, upon addition of different concentration of S1 endonuclease, the fluorescence was gradually restored owing to the reduction of FRET efficiency caused by S1 endonuclease specific cleavage ROX-ssDNA into short fragments, which reduced the electrostatic interaction between AgNRs and short oligonucleotide fragment. This assay strategy exhibited a high sensitivity and excellent specificity for S1 endonuclease with a detection limit of 0.004 U/mL and a dynamic concentration range from 0.01 U/mL to 5.0 U/mL. In addition, the capabilities for screening of S1 endonuclease inhibitors and S1 endonuclease detection from complex biological matrixes were also verified.
2019, 30(3): 545-548
doi: 10.1016/j.cclet.2018.11.020
Abstract:
Bisulfite (HSO3-) is an important sulfur dioxide (SO2) derivative, which plays a major role in many physiological processes and is also closely associated with a variety of diseases. Thus the development of highly selective and sensitive fluorescent probes is essential to detect HSO3- in living cells. In this work, we report the synthesis and analysis of a ratiometric fluorescent probe for selective detection of HSO3- based on the 1, 4-nucleophilic addition reaction with the carbazole as an electron donor (D) and aldehyde group as an electron acceptor (A). The addition of HSO3- and other ions to our probe can be observed by UV vis and fluorescence spectrometry. Our investigation proved that the probe is highly selective and sensitive for HSO3- and ratiometric changes. Moreover, the probe has good cell permeability and was successfully applied to the detection of exogenous HSO3- in Hela cells and C. elegans.
Bisulfite (HSO3-) is an important sulfur dioxide (SO2) derivative, which plays a major role in many physiological processes and is also closely associated with a variety of diseases. Thus the development of highly selective and sensitive fluorescent probes is essential to detect HSO3- in living cells. In this work, we report the synthesis and analysis of a ratiometric fluorescent probe for selective detection of HSO3- based on the 1, 4-nucleophilic addition reaction with the carbazole as an electron donor (D) and aldehyde group as an electron acceptor (A). The addition of HSO3- and other ions to our probe can be observed by UV vis and fluorescence spectrometry. Our investigation proved that the probe is highly selective and sensitive for HSO3- and ratiometric changes. Moreover, the probe has good cell permeability and was successfully applied to the detection of exogenous HSO3- in Hela cells and C. elegans.
2019, 30(3): 549-552
doi: 10.1016/j.cclet.2018.11.026
Abstract:
We report a facile, effective and rapid screening method for the determination of total fluoroquinolones (FQs) in milk using lanthanide coordination polymer nanomaterials as the sensing platform. The nonluminescent coordination polymer nanosheets (CPNSs) used in this work are composed of adenosine monophosphate (AMP) and terbium (Tb3+) ions (AMP/Tb CPNSs). The as-prepared CPNSs were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy and fluorescence techniques. Tb3+ acts as the center ion of the coordination polymer, with AMP assembled through phosphate and amine groups. However, the reaction between FQs and AMP/Tb CPNSs noticeably turns on the fluorescence due to the strong coordination interaction between FQs and Tb3+. Under optimized conditions, the fluorescence intensity of AMP/Tb at 545 nm shows a linear relationship with FQ concentrations between 0.04 μmol/L and 5.0 μmol/L. The relative standard deviation (RSD) of the intraday precision is below 1%, and detection limits are as low as 0.01 μmol/L. The proposed method was successfully applied to the determination of FQs in milk samples.
We report a facile, effective and rapid screening method for the determination of total fluoroquinolones (FQs) in milk using lanthanide coordination polymer nanomaterials as the sensing platform. The nonluminescent coordination polymer nanosheets (CPNSs) used in this work are composed of adenosine monophosphate (AMP) and terbium (Tb3+) ions (AMP/Tb CPNSs). The as-prepared CPNSs were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy and fluorescence techniques. Tb3+ acts as the center ion of the coordination polymer, with AMP assembled through phosphate and amine groups. However, the reaction between FQs and AMP/Tb CPNSs noticeably turns on the fluorescence due to the strong coordination interaction between FQs and Tb3+. Under optimized conditions, the fluorescence intensity of AMP/Tb at 545 nm shows a linear relationship with FQ concentrations between 0.04 μmol/L and 5.0 μmol/L. The relative standard deviation (RSD) of the intraday precision is below 1%, and detection limits are as low as 0.01 μmol/L. The proposed method was successfully applied to the determination of FQs in milk samples.
2019, 30(3): 553-557
doi: 10.1016/j.cclet.2018.11.029
Abstract:
RNA modification has recently been proposed to play important roles in biological regulation. The detection and quantification of RNA modifications generally are challenging tasks since most of the modifications exist in low abundance in vivo. Here we developed an on-line trapping/capillary hydrophilic-interaction liquid chromatography/electrospray ionization-mass spectrometry (on-line trapping/cHILIC/MS) method for sensitive and simultaneous quantification of RNA modifications of N6-methyladenosine (m6A) and 5-methylcytosine (5-mC) from human blood. The hydrophilic organic-silica hybrid monolith was prepared using sol-gel combined with "thiol-ene" click reaction for the separation of nucleosides. A poly(MAA-co-EGDMA) monolithic capillary was used as the on-line trapping column. With the developed on-line trapping/cHILIC/MS analytical platform, the detection limits of m6A and 5-mC can reach to 0.06 fmol and 0.10 fmol. We then investigated the contents of m6A and 5-mC in human blood RNA from healthy persons at the age of 6-14 and 60-68 years. Our results showed that both m6A and 5-mC contents were significantly decreased in elder persons, suggesting the RNA modifications of m6A and 5-mC are correlated to aging.
RNA modification has recently been proposed to play important roles in biological regulation. The detection and quantification of RNA modifications generally are challenging tasks since most of the modifications exist in low abundance in vivo. Here we developed an on-line trapping/capillary hydrophilic-interaction liquid chromatography/electrospray ionization-mass spectrometry (on-line trapping/cHILIC/MS) method for sensitive and simultaneous quantification of RNA modifications of N6-methyladenosine (m6A) and 5-methylcytosine (5-mC) from human blood. The hydrophilic organic-silica hybrid monolith was prepared using sol-gel combined with "thiol-ene" click reaction for the separation of nucleosides. A poly(MAA-co-EGDMA) monolithic capillary was used as the on-line trapping column. With the developed on-line trapping/cHILIC/MS analytical platform, the detection limits of m6A and 5-mC can reach to 0.06 fmol and 0.10 fmol. We then investigated the contents of m6A and 5-mC in human blood RNA from healthy persons at the age of 6-14 and 60-68 years. Our results showed that both m6A and 5-mC contents were significantly decreased in elder persons, suggesting the RNA modifications of m6A and 5-mC are correlated to aging.
2019, 30(3): 558-562
doi: 10.1016/j.cclet.2018.12.013
Abstract:
Carboxylesterase 1 (CES1), one of the most abundant serine hydrolases in mammals, has drawn much attentions in recent years, owing to this enzyme involves in many physiological processes via hydrolysis of both endogenous esters and xenobiotic esters. Herein, to real-time monitor the activities of CES1 in various biological systems, a practical and isoform-specific fluorescent probe was developed on the basis of the substrate preference of CES1, as well as the structural and optical properties of BODIPY dyes. After screening of a panel of BODIPY ester derivatives, probe 1 displayed the best combination of specificity, sensitivity, enzymatic kinetics and applicability for monitoring CES1 activities in real samples. This probe was successfully used to detect CES1 activities in several biological systems including tissue preparations, living cells, tissue slices and zebrafish. Furthermore, the biomedical applications of probe 1 for screening of CES1 inhibitors were also demonstrated using tissue preparations or living cells as enzyme sources. In summary, a practical and broadly applicable tool for real-time monitoring CES1 in biological systems was developed and well-characterized, which held great promise for further investigations on CES1- associated drug discovery, clinical practice and fundamental research.
Carboxylesterase 1 (CES1), one of the most abundant serine hydrolases in mammals, has drawn much attentions in recent years, owing to this enzyme involves in many physiological processes via hydrolysis of both endogenous esters and xenobiotic esters. Herein, to real-time monitor the activities of CES1 in various biological systems, a practical and isoform-specific fluorescent probe was developed on the basis of the substrate preference of CES1, as well as the structural and optical properties of BODIPY dyes. After screening of a panel of BODIPY ester derivatives, probe 1 displayed the best combination of specificity, sensitivity, enzymatic kinetics and applicability for monitoring CES1 activities in real samples. This probe was successfully used to detect CES1 activities in several biological systems including tissue preparations, living cells, tissue slices and zebrafish. Furthermore, the biomedical applications of probe 1 for screening of CES1 inhibitors were also demonstrated using tissue preparations or living cells as enzyme sources. In summary, a practical and broadly applicable tool for real-time monitoring CES1 in biological systems was developed and well-characterized, which held great promise for further investigations on CES1- associated drug discovery, clinical practice and fundamental research.
2019, 30(3): 563-565
doi: 10.1016/j.cclet.2018.12.017
Abstract:
In this work, we presented a fluorescent probe (MCQ-DNBS) for selective and sensitive detection of biothiols based on a methylated chromenoquinoline (MCQ) derivative. Probe MCQ-DNBS was constructed by masking the OH group in MCQ with a common sensing unit, 2, 4-dinitrobezensulfonate group (DNBS) for biothiols. Due to the photo-induced electron transfer (PET) process between MCQ and DNBS, this probe was weekly fluorescent. Upon the addition of biothiols (Cys, Hcy and GSH), this probe emitted a strong red fluorescence (λlem max=613 nm) with a large Stokes shift (115 nm). In addition, fluorescence imaging of biothiols in living cells was successfully realized using MCQ-DNBS as a detector.
In this work, we presented a fluorescent probe (MCQ-DNBS) for selective and sensitive detection of biothiols based on a methylated chromenoquinoline (MCQ) derivative. Probe MCQ-DNBS was constructed by masking the OH group in MCQ with a common sensing unit, 2, 4-dinitrobezensulfonate group (DNBS) for biothiols. Due to the photo-induced electron transfer (PET) process between MCQ and DNBS, this probe was weekly fluorescent. Upon the addition of biothiols (Cys, Hcy and GSH), this probe emitted a strong red fluorescence (λlem max=613 nm) with a large Stokes shift (115 nm). In addition, fluorescence imaging of biothiols in living cells was successfully realized using MCQ-DNBS as a detector.
2019, 30(3): 566-568
doi: 10.1016/j.cclet.2018.11.014
Abstract:
Perfluorooctanoic acid (PFOA) or perfluorooctane sulphonate (PFOS) was one of the most prominent fluorosurfactants and applied widely in firefighting and daily chemical, etc. However, these surfactants have recently been identified as toxic and undegradability in the environment. Developing an efficient approach to environment-friendly fluorosurfactants is essential. A fluorocarbon branched chain strategy was adopted to develop /PFOS substitutes. A series of intermediates of novel branched fluorinated surfactants with CF3CF2CF2C(CF3)2 group were synthesized from perfluoro-2-methyl-2-pentene. All the steps were mild, easy-handled and cheap. It is expected to be a very significant direction for the development of non-bioaccumulable alternatives of PFOA or PFOS.
Perfluorooctanoic acid (PFOA) or perfluorooctane sulphonate (PFOS) was one of the most prominent fluorosurfactants and applied widely in firefighting and daily chemical, etc. However, these surfactants have recently been identified as toxic and undegradability in the environment. Developing an efficient approach to environment-friendly fluorosurfactants is essential. A fluorocarbon branched chain strategy was adopted to develop /PFOS substitutes. A series of intermediates of novel branched fluorinated surfactants with CF3CF2CF2C(CF3)2 group were synthesized from perfluoro-2-methyl-2-pentene. All the steps were mild, easy-handled and cheap. It is expected to be a very significant direction for the development of non-bioaccumulable alternatives of PFOA or PFOS.
Copper(Ⅱ)-catalyzed enantioselective conjugate addition of nitro esters to 2-enoyl-pyridine N-oxides
2019, 30(3): 569-572
doi: 10.1016/j.cclet.2018.11.024
Abstract:
A highly enantioselective Michael addition of nitro esters to 2-enoyl-pyridine N-oxides was developed by using chiral copper catalysts. The Michael addition products can be obtained in high yields and with up to 96% ee. Moreover, asymmetric Michael addition product of nitromethane to 2-enoyl-pyridine N-oxides can be obtained in one step. An analogue of nicotine, dihydro-2H-pyrrol 4b was synthesized with this developed method.
A highly enantioselective Michael addition of nitro esters to 2-enoyl-pyridine N-oxides was developed by using chiral copper catalysts. The Michael addition products can be obtained in high yields and with up to 96% ee. Moreover, asymmetric Michael addition product of nitromethane to 2-enoyl-pyridine N-oxides can be obtained in one step. An analogue of nicotine, dihydro-2H-pyrrol 4b was synthesized with this developed method.
2019, 30(3): 573-576
doi: 10.1016/j.cclet.2018.11.031
Abstract:
Fluorescence imaging has facilitated fluorescent probes to analyze the subcellular localization and dynamics of biological targets. In this paper, we reported a fluorogenic probe for bacteria imaging. The probe was an imidazolium-derived pyrene compound, which self-assembled to form nano-particles and the pyrene fluorescence was quenched by the aggregation effects. When the self-assembly nanoparticles interacted with anionic bacteria surfaces, synergistic effects of electrostatic interaction and hydrophobic force caused competing binding between bacteria surfaces and imidazoliums. This binding resulted in the disassembly of the aggregates to give fluorescence turn-on signal. Meanwhile, the probe bound bacteria surfaces and displayed both pyrene-excimer and pyrene-monomer fluorescence, which gave ratiometric signal. Then, fluorescent labeling by the probe enabled the two-photo ratiometric imaging of bacteria.
Fluorescence imaging has facilitated fluorescent probes to analyze the subcellular localization and dynamics of biological targets. In this paper, we reported a fluorogenic probe for bacteria imaging. The probe was an imidazolium-derived pyrene compound, which self-assembled to form nano-particles and the pyrene fluorescence was quenched by the aggregation effects. When the self-assembly nanoparticles interacted with anionic bacteria surfaces, synergistic effects of electrostatic interaction and hydrophobic force caused competing binding between bacteria surfaces and imidazoliums. This binding resulted in the disassembly of the aggregates to give fluorescence turn-on signal. Meanwhile, the probe bound bacteria surfaces and displayed both pyrene-excimer and pyrene-monomer fluorescence, which gave ratiometric signal. Then, fluorescent labeling by the probe enabled the two-photo ratiometric imaging of bacteria.
2019, 30(3): 577-581
doi: 10.1016/j.cclet.2018.12.002
Abstract:
Several cyclodextrin-cucurbit[6]uril-cowheeled [4]rotaxanes were synthesized through the cucurbit[6] uril-templated azide-alkyne 1, 3-dipolar cycloaddition. The intramolecular interaction between the aromatic axle and the capping groups of cyclodextrin moieties was investigated by UV-vis, fluorescence, circular dichroism and NMR spectroscopic studies. The rotational kinetic of the wheel around the axle can be manipulated by adjusting the temperature. The capping group apparently slowed down the rotation of the wheel, playing a role of the brake, and lowering the temperature can stop the rotation of the wheel on the NMR timescale.
Several cyclodextrin-cucurbit[6]uril-cowheeled [4]rotaxanes were synthesized through the cucurbit[6] uril-templated azide-alkyne 1, 3-dipolar cycloaddition. The intramolecular interaction between the aromatic axle and the capping groups of cyclodextrin moieties was investigated by UV-vis, fluorescence, circular dichroism and NMR spectroscopic studies. The rotational kinetic of the wheel around the axle can be manipulated by adjusting the temperature. The capping group apparently slowed down the rotation of the wheel, playing a role of the brake, and lowering the temperature can stop the rotation of the wheel on the NMR timescale.
2019, 30(3): 582-586
doi: 10.1016/j.cclet.2018.12.011
Abstract:
Hydroxylated multi-walled carbon nanotubes (h-MWCNTs) and carboxylated MWCNTs (c-MWCNTs) have potential applications in biomedicine, but their toxicity to human endothelial cells under stressed conditions associated with chronic diseases was less studied in vitro. This study stressed human umbilical vein endothelial cells (HUVECs) with ER stress inducer thapsigargin (TG), and investigated the toxicity of h-MWCNTs and c-MWCNTs to normal and stressed HUVECs. h-MWCNTs and c-MWCNTs modestly reduced cellular viability, significantly promoted soluble ICAM-1 (sICAM-1), soluble VCAM-1 (sVCAM-1) as well as intracellular ROS, and decreased the expression of transcription factor KLF2 and KLF4. Pre-treatment with TG significantly reduced cellular viability, promoted IL-6 and THP-1 monocyte adhesion, and increased the expression of a panel of ER stress genes. ANOVA indicated no interaction between MWCNTs and TG pre-treatment on most of the endpoints. It was concluded that the toxicity of h-MWCNTs and c-MWCNTs to HUVECs might not be exacerbated by ER stress inducer.
Hydroxylated multi-walled carbon nanotubes (h-MWCNTs) and carboxylated MWCNTs (c-MWCNTs) have potential applications in biomedicine, but their toxicity to human endothelial cells under stressed conditions associated with chronic diseases was less studied in vitro. This study stressed human umbilical vein endothelial cells (HUVECs) with ER stress inducer thapsigargin (TG), and investigated the toxicity of h-MWCNTs and c-MWCNTs to normal and stressed HUVECs. h-MWCNTs and c-MWCNTs modestly reduced cellular viability, significantly promoted soluble ICAM-1 (sICAM-1), soluble VCAM-1 (sVCAM-1) as well as intracellular ROS, and decreased the expression of transcription factor KLF2 and KLF4. Pre-treatment with TG significantly reduced cellular viability, promoted IL-6 and THP-1 monocyte adhesion, and increased the expression of a panel of ER stress genes. ANOVA indicated no interaction between MWCNTs and TG pre-treatment on most of the endpoints. It was concluded that the toxicity of h-MWCNTs and c-MWCNTs to HUVECs might not be exacerbated by ER stress inducer.
2019, 30(3): 587-591
doi: 10.1016/j.cclet.2018.12.014
Abstract:
The interaction between monosaccharides exhibits an important role in the assembly of monosaccharide-containing molecules. In this work, three common monosaccharides, glucose, galactose and mannose, are employed to investigate the effect of monosaccharide on the self-assembly of benzenetricarboxamide (BTA) core-containing molecules. In the presence of monosaccharides, three benzenetricarboxamide derivatives aggregate into different ordered structures. When alanine linkers are introduced to these molecules between the core and the monosacchride, morphologies of three types of monosaccharide BTAs turned to disordered, meanwhile their structures become similar with the increase of the length of alanine linkers, indicating the disappearance of the monosaccharide effects.
The interaction between monosaccharides exhibits an important role in the assembly of monosaccharide-containing molecules. In this work, three common monosaccharides, glucose, galactose and mannose, are employed to investigate the effect of monosaccharide on the self-assembly of benzenetricarboxamide (BTA) core-containing molecules. In the presence of monosaccharides, three benzenetricarboxamide derivatives aggregate into different ordered structures. When alanine linkers are introduced to these molecules between the core and the monosacchride, morphologies of three types of monosaccharide BTAs turned to disordered, meanwhile their structures become similar with the increase of the length of alanine linkers, indicating the disappearance of the monosaccharide effects.
2019, 30(3): 592-596
doi: 10.1016/j.cclet.2018.12.020
Abstract:
Luminogenic molecules with aggregation-induced emission (AIE) property are free of aggregationcaused quenching and thus have great potential in the fabrication of efficient non-doped OLEDs. Herein, a series of new carbazole-substituted siloles have been synthesized and characterized. Their crystal and electronic structures, thermal stabilities, electrochemical behaviors, and photophysical properties are thoroughly investigated. These silole derivatives exhibit prominent AIE characteristics with high emission efficiencies in solid films. They can function as light-emitting layers in non-doped OLEDs, affording eminent electroluminescence efficiencies of 17.59 cd/A, 12.55 lm/W and 5.63%, amongst the most efficient non-doped OLEDs based on fluorescent emitters, indicating their promising applications in OLEDs.
Luminogenic molecules with aggregation-induced emission (AIE) property are free of aggregationcaused quenching and thus have great potential in the fabrication of efficient non-doped OLEDs. Herein, a series of new carbazole-substituted siloles have been synthesized and characterized. Their crystal and electronic structures, thermal stabilities, electrochemical behaviors, and photophysical properties are thoroughly investigated. These silole derivatives exhibit prominent AIE characteristics with high emission efficiencies in solid films. They can function as light-emitting layers in non-doped OLEDs, affording eminent electroluminescence efficiencies of 17.59 cd/A, 12.55 lm/W and 5.63%, amongst the most efficient non-doped OLEDs based on fluorescent emitters, indicating their promising applications in OLEDs.
2019, 30(3): 597-600
doi: 10.1016/j.cclet.2018.12.027
Abstract:
A ligand-free nickel-catalyzed Kumada cross-coupling of aryl bromides and tert-butyl Grignard reagents led to the formation of a series of tert-butyl aryls in moderate to good yields, excellent tBu/iBu ratios, and good functional group compatibility. A radical coupling process is indicated and a mechanism with a Ni(Ⅰ)-Ni(Ⅲ) catalytic cycle is proposed.
A ligand-free nickel-catalyzed Kumada cross-coupling of aryl bromides and tert-butyl Grignard reagents led to the formation of a series of tert-butyl aryls in moderate to good yields, excellent tBu/iBu ratios, and good functional group compatibility. A radical coupling process is indicated and a mechanism with a Ni(Ⅰ)-Ni(Ⅲ) catalytic cycle is proposed.
2019, 30(3): 601-604
doi: 10.1016/j.cclet.2018.12.008
Abstract:
Understanding relationships between molecular structures and fluorescent properties is critical to enable rational deployment of fluorophores. 1-Acetylpyrene is an important pyrene-derivative, used extensively as an environment-sensitive probe. In the past, the fluorescence of 1-acetylpyrene was considered to be polarity-sensitive with a large positive solvatochromism, and its monomer emissions were believed in the range of 410-470 nm. In this paper, our experimental and theoretical studies showed that the monomer fluorescence of 1-acetylpyrene is centered at ~390 nm, which is similar to that of pyrene dyes and not polarity-sensitive. Previously observed "monomer emission" has been re-assigned to that of dimers, which represent the dominant existence form of 1-acetylpyrene in the solution phase, as a result of strong intermolecular π-π stacking interactions.
Understanding relationships between molecular structures and fluorescent properties is critical to enable rational deployment of fluorophores. 1-Acetylpyrene is an important pyrene-derivative, used extensively as an environment-sensitive probe. In the past, the fluorescence of 1-acetylpyrene was considered to be polarity-sensitive with a large positive solvatochromism, and its monomer emissions were believed in the range of 410-470 nm. In this paper, our experimental and theoretical studies showed that the monomer fluorescence of 1-acetylpyrene is centered at ~390 nm, which is similar to that of pyrene dyes and not polarity-sensitive. Previously observed "monomer emission" has been re-assigned to that of dimers, which represent the dominant existence form of 1-acetylpyrene in the solution phase, as a result of strong intermolecular π-π stacking interactions.
2019, 30(3): 605-609
doi: 10.1016/j.cclet.2018.10.018
Abstract:
A novel bimetallic Ni/Co-based metal-organic framework (Ni/Co-MOF) was successfully synthesized via a simple solvothermal method, and used as electrode material for high performance supercapacitors. After doping of Co element, the Ni/Co-MOF materials retain the original crystalline topology structure of Ni3(BTC)2·12H2O. The as-obtained Ni/Co-MOF demonstrates an excellent specific capacitance of 1067 and 780 F/g at current density of 1 and 10 A/g, respectively, and can also retain 68.4% of the original capacitance after 2500 cycles. These results suggest that bimetallic Ni/Co-based MOFs are promising materials for the next generation supercapacitance, owing to their excellent electrochemical performance. The synthetic procedure can be applied to synthesize other bimetallic MOFs and enhance their conductive property.
A novel bimetallic Ni/Co-based metal-organic framework (Ni/Co-MOF) was successfully synthesized via a simple solvothermal method, and used as electrode material for high performance supercapacitors. After doping of Co element, the Ni/Co-MOF materials retain the original crystalline topology structure of Ni3(BTC)2·12H2O. The as-obtained Ni/Co-MOF demonstrates an excellent specific capacitance of 1067 and 780 F/g at current density of 1 and 10 A/g, respectively, and can also retain 68.4% of the original capacitance after 2500 cycles. These results suggest that bimetallic Ni/Co-based MOFs are promising materials for the next generation supercapacitance, owing to their excellent electrochemical performance. The synthetic procedure can be applied to synthesize other bimetallic MOFs and enhance their conductive property.
2019, 30(3): 610-617
doi: 10.1016/j.cclet.2018.08.018
Abstract:
As an alloying type anode material, silicon is a promising alternative of graphitic carbon due to its high theoretical capacity and natural abundance. Developing an industrially viable silicon anode, however, is still a huge challenge because of several problems: First of all, the common process to synthesize a silicon anode is complicated, costly, and energy-intensive. Besides, the huge volume expansion, inevitable side reactions with the electrolyte, and low intrinsic conductivity of silicon are eventually responsible for the poor cyclability and unsatisfactory rate capability. Herein, we aim to address these issues by proposing synthesis of hollow Si@void@C yolk-shell microspheres from sand by low-temperature aluminothermic reduction, which energetically combines a cost-effective silicon source with an energy-efficient, highyield methodology. The hollow Si@void@C yolk-shell microspheres effectively accommodate the diffusion-induced stress by providing the hollow interior and the void space. Moreover, the carbon shell not only functions as an electrolyte-blocking layer to protect the silicon yolk from undesirable side reactions and SEI formation, but also acts as a conductive framework to reduce the resistance to electron and Li+ ion transport. Benefiting from these synergistic effects, the hollow Si@void@C yolk-shell microspheres exhibit superior long-term cyclability and rate capability.
As an alloying type anode material, silicon is a promising alternative of graphitic carbon due to its high theoretical capacity and natural abundance. Developing an industrially viable silicon anode, however, is still a huge challenge because of several problems: First of all, the common process to synthesize a silicon anode is complicated, costly, and energy-intensive. Besides, the huge volume expansion, inevitable side reactions with the electrolyte, and low intrinsic conductivity of silicon are eventually responsible for the poor cyclability and unsatisfactory rate capability. Herein, we aim to address these issues by proposing synthesis of hollow Si@void@C yolk-shell microspheres from sand by low-temperature aluminothermic reduction, which energetically combines a cost-effective silicon source with an energy-efficient, highyield methodology. The hollow Si@void@C yolk-shell microspheres effectively accommodate the diffusion-induced stress by providing the hollow interior and the void space. Moreover, the carbon shell not only functions as an electrolyte-blocking layer to protect the silicon yolk from undesirable side reactions and SEI formation, but also acts as a conductive framework to reduce the resistance to electron and Li+ ion transport. Benefiting from these synergistic effects, the hollow Si@void@C yolk-shell microspheres exhibit superior long-term cyclability and rate capability.
2019, 30(3): 618-623
doi: 10.1016/j.cclet.2018.12.018
Abstract:
The NO oxidation processes on CrO2(110) was investigated by virtue of DFT + U calculation together with microkinetic analysis, aiming to uncover the reaction mechanism and activity-limiting factors for CrO2 catalyst. It was found that NO oxidation on CrO2(110) has to be triggered with the lattice Obri involved (Mars-van Krevelen mechanism) rather than the Langmuir-Hinshelwood path occurring at the Cr5c sites alone. Specifically, the optimal reaction path was identified. Quantitatively, the microkinetic analysis showed that CrO2(110) can exhibit a high turnover rate of 0.978 s-1 for NO oxidation at room temperature. Such an activity could originate from the bifunctional synergetic catalytic mechanism, in which the Cr5c sites can exclusively adsorb NO and the Obri is very reactive and provides oxidative species. However, it is worth noting that, as the reactive Obri tightly binds NO2, the nitrate species was found to be difficult removed and constituted the key poisoning species, eventually limiting the overall activity of CrO2. This work demonstrated the considerable catalytic ability of CrO2 for NO oxidation at room temperature, and the understanding may facilitate the further design of more active Cr-based catalyst.
The NO oxidation processes on CrO2(110) was investigated by virtue of DFT + U calculation together with microkinetic analysis, aiming to uncover the reaction mechanism and activity-limiting factors for CrO2 catalyst. It was found that NO oxidation on CrO2(110) has to be triggered with the lattice Obri involved (Mars-van Krevelen mechanism) rather than the Langmuir-Hinshelwood path occurring at the Cr5c sites alone. Specifically, the optimal reaction path was identified. Quantitatively, the microkinetic analysis showed that CrO2(110) can exhibit a high turnover rate of 0.978 s-1 for NO oxidation at room temperature. Such an activity could originate from the bifunctional synergetic catalytic mechanism, in which the Cr5c sites can exclusively adsorb NO and the Obri is very reactive and provides oxidative species. However, it is worth noting that, as the reactive Obri tightly binds NO2, the nitrate species was found to be difficult removed and constituted the key poisoning species, eventually limiting the overall activity of CrO2. This work demonstrated the considerable catalytic ability of CrO2 for NO oxidation at room temperature, and the understanding may facilitate the further design of more active Cr-based catalyst.
2019, 30(3): 624-629
doi: 10.1016/j.cclet.2018.10.039
Abstract:
High active and durable non-noble metal electrocatalysts are urgently developed to satisfy the high performance oxygen reduction reaction (ORR). We successfully synthesized Co-CoOx anchored on nitrogen-doped carbon via a facile sand-bath method (SBM), i.e., Co-CoOx/N-C (SBM). The as-obtained Co-CoOx/N-C (SBM) exhibited overwhelming superiorities to Co-CoO/N-C prepared by conventional heat treatment (CHT), particularly in electrochemical performance of ORR. Although Co-CoOx/N-C (SBM) showed smaller specific surface area of 276.8 m2/g than that of 939.5 m2/g from Co-CoO/N-C (CHT), the Co-CoOx/N-C (SBM) performed larger pore diameter and more Co3O4 active component resulting in better ORR performance in 0.1 mol/L KOH solution. The Co-CoOx/N-C (SBM) delivered onset potential of 0.91 V vs. RHE, mid-wave potential of 0.85 V vs. RHE and limited current density of 5.46 mA/cm2 much better than those of the Co-CoO/N-C (CHT). Furthermore, Co-CoOx/N-C (SBM) showed greater stability and better methanol tolerance superior to the commercial 20 wt% Pt/C.
High active and durable non-noble metal electrocatalysts are urgently developed to satisfy the high performance oxygen reduction reaction (ORR). We successfully synthesized Co-CoOx anchored on nitrogen-doped carbon via a facile sand-bath method (SBM), i.e., Co-CoOx/N-C (SBM). The as-obtained Co-CoOx/N-C (SBM) exhibited overwhelming superiorities to Co-CoO/N-C prepared by conventional heat treatment (CHT), particularly in electrochemical performance of ORR. Although Co-CoOx/N-C (SBM) showed smaller specific surface area of 276.8 m2/g than that of 939.5 m2/g from Co-CoO/N-C (CHT), the Co-CoOx/N-C (SBM) performed larger pore diameter and more Co3O4 active component resulting in better ORR performance in 0.1 mol/L KOH solution. The Co-CoOx/N-C (SBM) delivered onset potential of 0.91 V vs. RHE, mid-wave potential of 0.85 V vs. RHE and limited current density of 5.46 mA/cm2 much better than those of the Co-CoO/N-C (CHT). Furthermore, Co-CoOx/N-C (SBM) showed greater stability and better methanol tolerance superior to the commercial 20 wt% Pt/C.
2019, 30(3): 630-633
doi: 10.1016/j.cclet.2018.11.007
Abstract:
Preferential depositing coordination polymers onto substrates is of significance in realizing the potential of the coordination polymers for applications such as electronics, batteries, personal wearable devices. In this work, we reported a room-temperature method to deposit self-adhesive coordination polymers nanoplates on glass slides preferentially. Optical microscopy and scanning electron microscopy were employed to characterize the shape and thickness of the film. By investigating the humidity and concentration of the nanoplates, structure change between disk-like film and ring-like film was illustrated. A phase-diagram was drawn to distinguish the disk-like ring-like depositions. The preferential deposition of nanoplates can give the possibility to explore further applications of coordination polymers in the future.
Preferential depositing coordination polymers onto substrates is of significance in realizing the potential of the coordination polymers for applications such as electronics, batteries, personal wearable devices. In this work, we reported a room-temperature method to deposit self-adhesive coordination polymers nanoplates on glass slides preferentially. Optical microscopy and scanning electron microscopy were employed to characterize the shape and thickness of the film. By investigating the humidity and concentration of the nanoplates, structure change between disk-like film and ring-like film was illustrated. A phase-diagram was drawn to distinguish the disk-like ring-like depositions. The preferential deposition of nanoplates can give the possibility to explore further applications of coordination polymers in the future.
2019, 30(3): 634-637
doi: 10.1016/j.cclet.2018.11.010
Abstract:
Searching for highly efficient catalysts toward dehydrogenation of hydrazine for chemical hydrogen storage is highly desirable for the development of hydrogen economy. Herein, we report a simple in situ co-reduction synthesis of NiPt nanoparticles supported on CeO2 nanospheres and their superior catalytic performance for hydrogen generation from alkaline solution of hydrazine at room temperature. Thanks to the strong electronic interaction arising from synergistic effect at atomic lever and support-metal interaction between NiPt and CeO2. The obtained Ni5Pt5-CeO2 catalyst exhibits 100% hydrogen selectivity and superior catalytic performance for hydrogen generation from alkaline solution of hydrazine at room temperature, with a TOF value of 416 h-1.
Searching for highly efficient catalysts toward dehydrogenation of hydrazine for chemical hydrogen storage is highly desirable for the development of hydrogen economy. Herein, we report a simple in situ co-reduction synthesis of NiPt nanoparticles supported on CeO2 nanospheres and their superior catalytic performance for hydrogen generation from alkaline solution of hydrazine at room temperature. Thanks to the strong electronic interaction arising from synergistic effect at atomic lever and support-metal interaction between NiPt and CeO2. The obtained Ni5Pt5-CeO2 catalyst exhibits 100% hydrogen selectivity and superior catalytic performance for hydrogen generation from alkaline solution of hydrazine at room temperature, with a TOF value of 416 h-1.
2019, 30(3): 638-642
doi: 10.1016/j.cclet.2018.08.004
Abstract:
In this work, we report a facile synthesis method for NDs-Au@AgNPs surface-enhanced Raman scattering (SERS) substrate using Au seeds prepared by nitrogen-rich quantum dots (NDs). As a new member of quantum-dots family, NDs are rich in nitrogen and oxygen-containing functional groups and therefore can be used as an efficient reducing and stabilizing agent for the synthesis of AuNPs. The NDs-Au@AgNPs with core-shell structures was synthesized by seed-mediated growth method in presence of NDs-AuNPs seeds and exhibited high SERS activity with a high SERS enhancement factor of 107. The NDs-Au@AgNPs SERS substrate was effectively used for the recognition and detection of isomers of meta, ortho and para nitroanilines, while commercial SERS substrate cannot. In addition, the possible adsorption behavior was further studied, which is of great significance for the related work about differentiation of isomers and the mechanism of SERS enhancement.
In this work, we report a facile synthesis method for NDs-Au@AgNPs surface-enhanced Raman scattering (SERS) substrate using Au seeds prepared by nitrogen-rich quantum dots (NDs). As a new member of quantum-dots family, NDs are rich in nitrogen and oxygen-containing functional groups and therefore can be used as an efficient reducing and stabilizing agent for the synthesis of AuNPs. The NDs-Au@AgNPs with core-shell structures was synthesized by seed-mediated growth method in presence of NDs-AuNPs seeds and exhibited high SERS activity with a high SERS enhancement factor of 107. The NDs-Au@AgNPs SERS substrate was effectively used for the recognition and detection of isomers of meta, ortho and para nitroanilines, while commercial SERS substrate cannot. In addition, the possible adsorption behavior was further studied, which is of great significance for the related work about differentiation of isomers and the mechanism of SERS enhancement.
2019, 30(3): 643-649
doi: 10.1016/j.cclet.2018.10.013
Abstract:
Three novel β-cyclodextrin compounds derived with piperidine which is flexible, L-proline containing a chiral center, ionic liquid with 3, 5-diamino-1, 2, 4-triazole as the cation were designed and synthesized as chiral selectors for enantiomer separation, whose name were (mono-6-deoxy-6-(piperidine)-β-cyclodextrin, mono-6-deoxy-6-(L-proline)-β-cyclodextrin, mono-6-deoxy-6-(3, 5-diamino-1, 2, 4-triazole)-β-cyclodextrin, multi-substituted 3, 5-diamino-1, 2, 4-triazole-(p-toluenesulfonic)-β-cyclodextrin), respectively. In addition, to enhance the polarity of chiral stationary phases, hydrosilylation and silylation reactions were implemented to derive ordinary silica, the common used selector carrier, to hydride silica, whose surface is covered with proton. 31 pyrrolidine compounds and some chiral drugs were tested in both polar organic mobile phase mode and normal mobile phase mode. 6-Deoxy-6-Lproline-β-cyclodextrin-CSP showed satisfactory separations in polar organic mobile phase mode and exihibited a strong separation capability in different pH values; multi-substituted 3, 5-diamino-1, 2, 4- triazole-(p-toluenesulfonic)-β-cyclodextrin-CSP can separate pyrrolidine compounds in both mobile phase modes with high resolutions and separation efficiency compared to commercially available CSPs, making it to be the most valuable object to study. The composition of mobile phase, type of stationary phase as well as the peak problem of chromatograms was discussed deeply.
Three novel β-cyclodextrin compounds derived with piperidine which is flexible, L-proline containing a chiral center, ionic liquid with 3, 5-diamino-1, 2, 4-triazole as the cation were designed and synthesized as chiral selectors for enantiomer separation, whose name were (mono-6-deoxy-6-(piperidine)-β-cyclodextrin, mono-6-deoxy-6-(L-proline)-β-cyclodextrin, mono-6-deoxy-6-(3, 5-diamino-1, 2, 4-triazole)-β-cyclodextrin, multi-substituted 3, 5-diamino-1, 2, 4-triazole-(p-toluenesulfonic)-β-cyclodextrin), respectively. In addition, to enhance the polarity of chiral stationary phases, hydrosilylation and silylation reactions were implemented to derive ordinary silica, the common used selector carrier, to hydride silica, whose surface is covered with proton. 31 pyrrolidine compounds and some chiral drugs were tested in both polar organic mobile phase mode and normal mobile phase mode. 6-Deoxy-6-Lproline-β-cyclodextrin-CSP showed satisfactory separations in polar organic mobile phase mode and exihibited a strong separation capability in different pH values; multi-substituted 3, 5-diamino-1, 2, 4- triazole-(p-toluenesulfonic)-β-cyclodextrin-CSP can separate pyrrolidine compounds in both mobile phase modes with high resolutions and separation efficiency compared to commercially available CSPs, making it to be the most valuable object to study. The composition of mobile phase, type of stationary phase as well as the peak problem of chromatograms was discussed deeply.
2019, 30(3): 650-652
doi: 10.1016/j.cclet.2018.10.015
Abstract:
Simultaneous separation and detection of three organomercury species, namely methylmercury (MeHg), ethylmercury (EtHg), and phenylmercury (PhHg), was performed by using capillary electrophoresis (CE) with UV detection. Pre-column derivatization with thiosalicylic acid and on-line salt-induced stacking significantly improved the detection performance. Buffer pH, ion strength, and additive were optimized for CE separation, concentration of NaCl in sample solution and injection time were optimized for on-line stacking. The limits of detection were 76.9, 83.0 and 76.4 mg/L for PhHg, EtHg and MeHg, respectively. The developed method was validated by certified reference material and liquid chromatography-atomic fluorescence spectroscopy, which suggests this method could be useful in the speciation of organomercury compounds in biological samples.
Simultaneous separation and detection of three organomercury species, namely methylmercury (MeHg), ethylmercury (EtHg), and phenylmercury (PhHg), was performed by using capillary electrophoresis (CE) with UV detection. Pre-column derivatization with thiosalicylic acid and on-line salt-induced stacking significantly improved the detection performance. Buffer pH, ion strength, and additive were optimized for CE separation, concentration of NaCl in sample solution and injection time were optimized for on-line stacking. The limits of detection were 76.9, 83.0 and 76.4 mg/L for PhHg, EtHg and MeHg, respectively. The developed method was validated by certified reference material and liquid chromatography-atomic fluorescence spectroscopy, which suggests this method could be useful in the speciation of organomercury compounds in biological samples.
2019, 30(3): 653-655
doi: 10.1016/j.cclet.2018.11.032
Abstract:
A series of novel benzofuran-isatin-hydroxylimine/thiosemicarbazide hybrids were designed, synthesized and evaluated for their in vitro anti-TB activities against drug-sensitive MTB H37Rv and MDR-TB isolates as well as cytotoxicity. All benzofuran-isatin-hydroxylimine/thiosemicarbazide hybrids exhibited considerable in vitro anti-mycobacterial activities against the tested three MTB strains, and all of them also showed acceptable cytotoxicity. The most active hybrid 7f was >4.8 and >51 folds more potent than the first line anti-TB agents RIF and INH against both drug-sensitive MTB H37Rv and MDR-TB isolates, respectively. The results demonstrated the potential utility of benzofuran-isatin-hydroxylimine/-thiosemicarbazide hybrids as anti-TB agents.
A series of novel benzofuran-isatin-hydroxylimine/thiosemicarbazide hybrids were designed, synthesized and evaluated for their in vitro anti-TB activities against drug-sensitive MTB H37Rv and MDR-TB isolates as well as cytotoxicity. All benzofuran-isatin-hydroxylimine/thiosemicarbazide hybrids exhibited considerable in vitro anti-mycobacterial activities against the tested three MTB strains, and all of them also showed acceptable cytotoxicity. The most active hybrid 7f was >4.8 and >51 folds more potent than the first line anti-TB agents RIF and INH against both drug-sensitive MTB H37Rv and MDR-TB isolates, respectively. The results demonstrated the potential utility of benzofuran-isatin-hydroxylimine/-thiosemicarbazide hybrids as anti-TB agents.
2019, 30(3): 656-659
doi: 10.1016/j.cclet.2018.12.003
Abstract:
Magnetic nanoparticles (MNPs) are widely used for the immobilization of enzyme owing to the unique properties such as good biocompatibility and rapid separation. Herein, we used Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) as the carrier core with (3-aminopropyl)triethoxysilane (APTES) modification by our approach, in which α-glucosidase was stereoscopically immobilized on the surface of Fe3O4 MNPs via covalent binding. The result of immobilization was characterized by scanning electron microscope (SEM) and fourier transform-infrared spectroscopy (FT-IR). Then we optimized some key parameters of the immobilization reaction, including the ratio of MNPs to enzyme, GA concentration, crosslinking time and immobilization time. Moreover, under the optimal conditions, pH tolerance, thermo stability and reusability of the immobilized enzyme were investigated and compared with the free one. In order to evaluate the change of the affinity of the enzyme to its specific substrate after immobilization, the Michaelis-Menten constant (Km) was also studied. Finally, the immobilized α-glucosidase combining with high performance liquid chromatography-tandem mass spectrometry technique (HPLC-MS/MS) was applied to screen and identify eight inhibitors from Polygonum cuspidatum extract. These results indicated that the established method had the broad prospects for biotechnological applications.
Magnetic nanoparticles (MNPs) are widely used for the immobilization of enzyme owing to the unique properties such as good biocompatibility and rapid separation. Herein, we used Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) as the carrier core with (3-aminopropyl)triethoxysilane (APTES) modification by our approach, in which α-glucosidase was stereoscopically immobilized on the surface of Fe3O4 MNPs via covalent binding. The result of immobilization was characterized by scanning electron microscope (SEM) and fourier transform-infrared spectroscopy (FT-IR). Then we optimized some key parameters of the immobilization reaction, including the ratio of MNPs to enzyme, GA concentration, crosslinking time and immobilization time. Moreover, under the optimal conditions, pH tolerance, thermo stability and reusability of the immobilized enzyme were investigated and compared with the free one. In order to evaluate the change of the affinity of the enzyme to its specific substrate after immobilization, the Michaelis-Menten constant (Km) was also studied. Finally, the immobilized α-glucosidase combining with high performance liquid chromatography-tandem mass spectrometry technique (HPLC-MS/MS) was applied to screen and identify eight inhibitors from Polygonum cuspidatum extract. These results indicated that the established method had the broad prospects for biotechnological applications.
2019, 30(3): 660-663
doi: 10.1016/j.cclet.2018.10.001
Abstract:
Gold nanoclusters were rapid synthesized within 3 min at 120℃ by using papaya juice as a capping and reducing agent (P-AuNCs). The properties of the fluorescent probe were characterized by fluorescent spectroscopy, UV-vis spectroscopy, dynamic light scattering and transmission electron microscope. Based on the surface electron density increase-induced fluorescence enhancing principle, a high selective method for detection of L-lysine was developed with the as-prepared P-AuNCs coupling the fluorescence emission at 440 nm. The fluorescent probe showed high stability and good biocompatibility. Its fluorescence intensity was found to be linearly dependent on the L-lysine concentration in the range of 10.0 μmol/L to 1000.0 μmol/L (R2=0.969) with a limit of detection of 6.0 μmol/L. Furthermore, the PAuNCs based approach was applied for monitoring the urine L-lysine contents, demonstrating great potential of fluorescent probes in real samples analysis.
Gold nanoclusters were rapid synthesized within 3 min at 120℃ by using papaya juice as a capping and reducing agent (P-AuNCs). The properties of the fluorescent probe were characterized by fluorescent spectroscopy, UV-vis spectroscopy, dynamic light scattering and transmission electron microscope. Based on the surface electron density increase-induced fluorescence enhancing principle, a high selective method for detection of L-lysine was developed with the as-prepared P-AuNCs coupling the fluorescence emission at 440 nm. The fluorescent probe showed high stability and good biocompatibility. Its fluorescence intensity was found to be linearly dependent on the L-lysine concentration in the range of 10.0 μmol/L to 1000.0 μmol/L (R2=0.969) with a limit of detection of 6.0 μmol/L. Furthermore, the PAuNCs based approach was applied for monitoring the urine L-lysine contents, demonstrating great potential of fluorescent probes in real samples analysis.
2019, 30(3): 664-667
doi: 10.1016/j.cclet.2018.10.021
Abstract:
An electrochemical immunosensor was developed for ultrasensitive detection of microcystin-LR in water. MIL-101, a porous metal-organic frameworks (MOFs) material based on trivalent chromium skeleton were synthesized by hydrothermal synthesis method, and loaded with Au nanoparticles (Au NPs) to prepare Au NPs@MIL-101 composite materials which were used as a marker to label anti microcystin-LR (Anti-MC-LR). The composite materials have strong catalytic properties to the oxidation of ascorbic acid. Anti-MC-LR was immobilized on glassy carbon electrode surface using electrodeposition graphene oxide (GO) as an immobilization matrix to construct a competitive microcystin-LR immunosensor. The electrochemical immunosensor display linear relationship in the range of 0.05 ng/mL-75 μg/mL with linear correlation coefficient of 0.9951 and detection limit of 0.02 ng/mL (S/N=3). This sensor was used to detect microcystin-LR in the water sample. The recovery was 102.43%, which is satisfied. The good testing results indicate the sensor has a great prospect in practical application.
An electrochemical immunosensor was developed for ultrasensitive detection of microcystin-LR in water. MIL-101, a porous metal-organic frameworks (MOFs) material based on trivalent chromium skeleton were synthesized by hydrothermal synthesis method, and loaded with Au nanoparticles (Au NPs) to prepare Au NPs@MIL-101 composite materials which were used as a marker to label anti microcystin-LR (Anti-MC-LR). The composite materials have strong catalytic properties to the oxidation of ascorbic acid. Anti-MC-LR was immobilized on glassy carbon electrode surface using electrodeposition graphene oxide (GO) as an immobilization matrix to construct a competitive microcystin-LR immunosensor. The electrochemical immunosensor display linear relationship in the range of 0.05 ng/mL-75 μg/mL with linear correlation coefficient of 0.9951 and detection limit of 0.02 ng/mL (S/N=3). This sensor was used to detect microcystin-LR in the water sample. The recovery was 102.43%, which is satisfied. The good testing results indicate the sensor has a great prospect in practical application.
2019, 30(3): 668-671
doi: 10.1016/j.cclet.2018.11.001
Abstract:
A series of (R)-2-phenyl-4, 5-dihydrothiazole-4-carboxamide derivatives containing a sulfur ether moiety were synthesized and characterized on the basis of NMR and elemental analysis (EA). The crystal structure of (R)-N-(2-methyl-1-(methylthio)propan-2-yl)-2-(4-nitrophenyl)-4, 5-dihydrothiazole-4-carboxamide (13d) was determined to show R configuration. The bioasssy results indicated that most title compounds displayed good and broad spectrum antifungal activities against several phytopathogenic fungi. The structure activity relationships were discussed. Based on the antifungal activity of title compounds against Phytophthora capsici, a CoMSIA calculation was performed to establish a 3D-QSAR model, which revealed that electrostatic and hydrophobic fields were the two most significant factors for antifungal activity. According to the established 3D-QSAR model, structure optimization was carried out to find (R)-N-((R)-1-(methylthio)propan-2-yl)-2-(p-tolyl)-4, 5-dihydrothiazole-4-carboxamide (15h) with excellent activity against Phytophthora capsici, thus emerging as a new lead compound for novel antiphytopathogenic fungus agent development.
A series of (R)-2-phenyl-4, 5-dihydrothiazole-4-carboxamide derivatives containing a sulfur ether moiety were synthesized and characterized on the basis of NMR and elemental analysis (EA). The crystal structure of (R)-N-(2-methyl-1-(methylthio)propan-2-yl)-2-(4-nitrophenyl)-4, 5-dihydrothiazole-4-carboxamide (13d) was determined to show R configuration. The bioasssy results indicated that most title compounds displayed good and broad spectrum antifungal activities against several phytopathogenic fungi. The structure activity relationships were discussed. Based on the antifungal activity of title compounds against Phytophthora capsici, a CoMSIA calculation was performed to establish a 3D-QSAR model, which revealed that electrostatic and hydrophobic fields were the two most significant factors for antifungal activity. According to the established 3D-QSAR model, structure optimization was carried out to find (R)-N-((R)-1-(methylthio)propan-2-yl)-2-(p-tolyl)-4, 5-dihydrothiazole-4-carboxamide (15h) with excellent activity against Phytophthora capsici, thus emerging as a new lead compound for novel antiphytopathogenic fungus agent development.
2019, 30(3): 672-675
doi: 10.1016/j.cclet.2018.11.006
Abstract:
Cell adhesion is the basis for some cell isolation methods, and is influenced by both of the biochemical and topographic characteristics of the substrates. Herein, based on cell imprinting and click chemistry, we have developed a cell-imprinted polydimethylsiloxane (PDMS) with aptamer functionalization (APTCIS). The atom force microscopic analysis results showed that the hierarchical structure matching well with the target cells is successfully introduced on the surface of the APT-CIS. By using the synergistic effects of hierarchical structure and aptamer affinity, the APT-CIS was successfully used for the selective cell adhesion, and 93.9%±0.8% of the captured cells could then be released. Thus, the APT-CIS holds promise in selective cell isolation and sorting fields.
Cell adhesion is the basis for some cell isolation methods, and is influenced by both of the biochemical and topographic characteristics of the substrates. Herein, based on cell imprinting and click chemistry, we have developed a cell-imprinted polydimethylsiloxane (PDMS) with aptamer functionalization (APTCIS). The atom force microscopic analysis results showed that the hierarchical structure matching well with the target cells is successfully introduced on the surface of the APT-CIS. By using the synergistic effects of hierarchical structure and aptamer affinity, the APT-CIS was successfully used for the selective cell adhesion, and 93.9%±0.8% of the captured cells could then be released. Thus, the APT-CIS holds promise in selective cell isolation and sorting fields.
2019, 30(3): 676-680
doi: 10.1016/j.cclet.2018.12.016
Abstract:
Sialylation is one of important glycosylation in human beings and plays an important role in cancer development. α2, 3-Linked and α2, 6-linked sialic acids are normally observed on the end of N-glycans and have different functions. Derivatization on sialic acid was designed to detect the different linkages by MALDI-TOF MS. In this study, a two-step derivatization by dimethylamine and ammonium hydroxide was improved to modify the sialic acid and made it easier to detect the different linkages of sialic acids on MALDI-TOF MS. Using this derivatization method, specific sialic acids linkages on N-glycans of protein samples such as fetuin and lactoferrinwere detected. For complex cell samples, increased α2, 3-linked and α2, 6-linked sialic acids on bi-antennary and tri-antennary N-glycans were observed in A549 cells induced by hypoxia environment. Taken together, our two-step derivatization of sialic acids offers a simple and accurate way to detect specific linkages on N-glycans with MALDI-TOF mass spectrometer.
Sialylation is one of important glycosylation in human beings and plays an important role in cancer development. α2, 3-Linked and α2, 6-linked sialic acids are normally observed on the end of N-glycans and have different functions. Derivatization on sialic acid was designed to detect the different linkages by MALDI-TOF MS. In this study, a two-step derivatization by dimethylamine and ammonium hydroxide was improved to modify the sialic acid and made it easier to detect the different linkages of sialic acids on MALDI-TOF MS. Using this derivatization method, specific sialic acids linkages on N-glycans of protein samples such as fetuin and lactoferrinwere detected. For complex cell samples, increased α2, 3-linked and α2, 6-linked sialic acids on bi-antennary and tri-antennary N-glycans were observed in A549 cells induced by hypoxia environment. Taken together, our two-step derivatization of sialic acids offers a simple and accurate way to detect specific linkages on N-glycans with MALDI-TOF mass spectrometer.
2019, 30(3): 681-685
doi: 10.1016/j.cclet.2018.09.017
Abstract:
Cobalt and nitrogen codoped carbon materials (Co-N-C) were fabricated by pyrolysis of the mixture of poly(4-vinylpyridine) and cobalt chloride using SiO2 nanoparticles as hard template, which were the first transition metal/nitrogen-codoped carbon bifunctional electrocatalyst derived from noncarbonizable polymer for ORR and HER. The as-made Co-N-C possessed hierarchical pore structure and high specific surface area, achieving excellent electrocatalytic performances for ORR and HER. Its ORR catalytic performances were comparable to those of Pt/C catalyst and its HER catalytic performances were superior to those of most doped carbon catalysts in KOH electrolyte. Moreover, its bifunctional electrocatalytic performances for ORR and HER were better than those of most bifunctional doped carbon catalysts in alkaline electrolyte.
Cobalt and nitrogen codoped carbon materials (Co-N-C) were fabricated by pyrolysis of the mixture of poly(4-vinylpyridine) and cobalt chloride using SiO2 nanoparticles as hard template, which were the first transition metal/nitrogen-codoped carbon bifunctional electrocatalyst derived from noncarbonizable polymer for ORR and HER. The as-made Co-N-C possessed hierarchical pore structure and high specific surface area, achieving excellent electrocatalytic performances for ORR and HER. Its ORR catalytic performances were comparable to those of Pt/C catalyst and its HER catalytic performances were superior to those of most doped carbon catalysts in KOH electrolyte. Moreover, its bifunctional electrocatalytic performances for ORR and HER were better than those of most bifunctional doped carbon catalysts in alkaline electrolyte.
2019, 30(3): 686-689
doi: 10.1016/j.cclet.2018.06.012
Abstract:
An efficient and facile approach has been developed for the construction of chondroitin sulfate E (CS-E) oligosaccharide precursors. In this approach, the disaccharide unit with the GalNAc-GlcA sequence was first elongated to form tetra- and hexasaccharides followed by the introduction of anomeric groups via glycosylation couplings. A number of CS-E tetra- and hexasaccharide precursors were prepared in high yields.
An efficient and facile approach has been developed for the construction of chondroitin sulfate E (CS-E) oligosaccharide precursors. In this approach, the disaccharide unit with the GalNAc-GlcA sequence was first elongated to form tetra- and hexasaccharides followed by the introduction of anomeric groups via glycosylation couplings. A number of CS-E tetra- and hexasaccharide precursors were prepared in high yields.
2019, 30(3): 690-693
doi: 10.1016/j.cclet.2018.10.009
Abstract:
Oleanolic acid (OA) and echinocystic acid (EA), two naturally occurring pentacyclic oleanane triterpenes, are gaining increasing attention due to their promising pharmacological activities. Conjugation with amphiphilic α(β)-cyclodextrin (CD) via "click chemistry" can improve their solubility and anti-HCV entry potency. In the present work, four water-soluble β-CD-pentacyclic triterpene conjugates were designed and synthesized, in which OA and EA was coupled to one of the primary hydroxyl groups of β-CD via ester and amide bonds. The structures of the conjugates were unambiguously determined by 1H NMR, 13C NMR and HRMS or MALDI-TOF-MS. All the conjugates showed lower hydrophobicity (AlogP) than their parent compounds and no significant cytotoxicity was found to HL-60, A549, Hela and Bel-7402 cells at concentrations up to 10 μmol/L. Further anti-HCV entry activity and mechanism studies are under way in our laboratory.
Oleanolic acid (OA) and echinocystic acid (EA), two naturally occurring pentacyclic oleanane triterpenes, are gaining increasing attention due to their promising pharmacological activities. Conjugation with amphiphilic α(β)-cyclodextrin (CD) via "click chemistry" can improve their solubility and anti-HCV entry potency. In the present work, four water-soluble β-CD-pentacyclic triterpene conjugates were designed and synthesized, in which OA and EA was coupled to one of the primary hydroxyl groups of β-CD via ester and amide bonds. The structures of the conjugates were unambiguously determined by 1H NMR, 13C NMR and HRMS or MALDI-TOF-MS. All the conjugates showed lower hydrophobicity (AlogP) than their parent compounds and no significant cytotoxicity was found to HL-60, A549, Hela and Bel-7402 cells at concentrations up to 10 μmol/L. Further anti-HCV entry activity and mechanism studies are under way in our laboratory.
2019, 30(3): 694-697
doi: 10.1016/j.cclet.2018.10.011
Abstract:
Cyanine dyes have attracted more and more interest due to their controllable assembly and disassembly process with biomolecular templates. The self-assembly of cyanine dye not only depend on the environment, but also on their structures. Here, we report assembly and disassembly of two cyanine dyes, a dimeric cyaine dye (TC-P4) and its corresponding monomer (TC). In PBS, these dyes could form aggregates. The parallel c-myc G-quadruplex as a template causes the transformation of TC-P4 from Haggregates to dimer and monomer; while duplex and single-stranded DNAs could not. The interaction between these DNAs motifs and TC could all induce the appearance of monomer band. Parallel c-myc Gquadruplex could enhance the fluorescence intensity of TC-P4 and TC. The self-assembly and disassembly of TC and TC-P4 could be regulated and used as probes for G-quadruplex recognition from duplex and single-stranded DNAs in solution.
Cyanine dyes have attracted more and more interest due to their controllable assembly and disassembly process with biomolecular templates. The self-assembly of cyanine dye not only depend on the environment, but also on their structures. Here, we report assembly and disassembly of two cyanine dyes, a dimeric cyaine dye (TC-P4) and its corresponding monomer (TC). In PBS, these dyes could form aggregates. The parallel c-myc G-quadruplex as a template causes the transformation of TC-P4 from Haggregates to dimer and monomer; while duplex and single-stranded DNAs could not. The interaction between these DNAs motifs and TC could all induce the appearance of monomer band. Parallel c-myc Gquadruplex could enhance the fluorescence intensity of TC-P4 and TC. The self-assembly and disassembly of TC and TC-P4 could be regulated and used as probes for G-quadruplex recognition from duplex and single-stranded DNAs in solution.
2019, 30(3): 698-701
doi: 10.1016/j.cclet.2018.10.023
Abstract:
We report herein an efficient catalytic epoxidation reaction for the synthesis of epoxyketone (tert-butyl ((S)-4-methyl-1-((R)-2-methyloxiran-2-yl)-1-oxopentan-2-yl)carbamate), which is an important synthetic intermediate of carfilzomib. A series of bioinspired manganese complexes bearing N4 ligands are carefully investigated in the epoxidation of enone precursor with H2O2 as oxidant in the presence of carboxylic acid (e.g., acetic acid).
We report herein an efficient catalytic epoxidation reaction for the synthesis of epoxyketone (tert-butyl ((S)-4-methyl-1-((R)-2-methyloxiran-2-yl)-1-oxopentan-2-yl)carbamate), which is an important synthetic intermediate of carfilzomib. A series of bioinspired manganese complexes bearing N4 ligands are carefully investigated in the epoxidation of enone precursor with H2O2 as oxidant in the presence of carboxylic acid (e.g., acetic acid).
2019, 30(3): 702-706
doi: 10.1016/j.cclet.2018.09.022
Abstract:
The palladium-catalyzed late-stage aroylation of 4-methyl-1, 5-diaryl-1H-pyrazole-3-carboxylates has been developed via direct and exclusive mono-Csp2-H bond activation with broad substrate scope and good functional group tolerance. A dual-core dimeric palladacycle is confirmed by X-ray single crystal crystallography, and probably serves as an active species in the catalytic cycle.
The palladium-catalyzed late-stage aroylation of 4-methyl-1, 5-diaryl-1H-pyrazole-3-carboxylates has been developed via direct and exclusive mono-Csp2-H bond activation with broad substrate scope and good functional group tolerance. A dual-core dimeric palladacycle is confirmed by X-ray single crystal crystallography, and probably serves as an active species in the catalytic cycle.
2019, 30(3): 707-709
doi: 10.1016/j.cclet.2018.10.024
Abstract:
Low-molecular-weight supramolecular hydrogels are of significant attractive soft materials as particular functions can be facilely introduced by the straightforward fabrication of such self-assembled systems. In this study, an azobenzene-bridged dicationic pyridinium salt was synthesized, from which photoresponsive supramolecular hydrogel could be fabricated through the π-π stacking and hydrophobic interactions in the aqueous solution. By taking advantages of the UV-vis light induced E/Z photoisomerization behaviors of the incorporated azobenzene photochromophore, reversible gel-sol transformation of such supramolecular hydrogel could be achieved under the alternating UV-vis irradiation conditions. We believed that this photoresponsive supramolecular hydrogel will be a good supplementary in the creation of intelligent soft material.
Low-molecular-weight supramolecular hydrogels are of significant attractive soft materials as particular functions can be facilely introduced by the straightforward fabrication of such self-assembled systems. In this study, an azobenzene-bridged dicationic pyridinium salt was synthesized, from which photoresponsive supramolecular hydrogel could be fabricated through the π-π stacking and hydrophobic interactions in the aqueous solution. By taking advantages of the UV-vis light induced E/Z photoisomerization behaviors of the incorporated azobenzene photochromophore, reversible gel-sol transformation of such supramolecular hydrogel could be achieved under the alternating UV-vis irradiation conditions. We believed that this photoresponsive supramolecular hydrogel will be a good supplementary in the creation of intelligent soft material.
2019, 30(3): 710-713
doi: 10.1016/j.cclet.2018.11.012
Abstract:
The complexation of γ-allyloxymethyl 18-crown-6 (AC6) induced inferior mechanical and thermal properties of polyimide (PI) in spite of lowered dielectric constant (k). To solve this puzzle, tetrakis-(dimethylsiloxy)-silane was employed to crosslink the complex of AC6 and PI (AC6-PI) through hydrosilylation reaction. The crosslinked AC6-PI (SiAC-PI) composites possessed excellent mechanical and thermal properties as well as low k. The tensile strength and fracture energy of SiAC-PI were increased by 87% and 716%, and the glass transition temperature and 5% weight loss temperature elevated 14.5℃ and 38.8℃, respectively, compared with those of AC6-PI. The structure of SiAC-PI was characterized by FTIR spectra, crosslinked density and XRD diffraction patterns.
The complexation of γ-allyloxymethyl 18-crown-6 (AC6) induced inferior mechanical and thermal properties of polyimide (PI) in spite of lowered dielectric constant (k). To solve this puzzle, tetrakis-(dimethylsiloxy)-silane was employed to crosslink the complex of AC6 and PI (AC6-PI) through hydrosilylation reaction. The crosslinked AC6-PI (SiAC-PI) composites possessed excellent mechanical and thermal properties as well as low k. The tensile strength and fracture energy of SiAC-PI were increased by 87% and 716%, and the glass transition temperature and 5% weight loss temperature elevated 14.5℃ and 38.8℃, respectively, compared with those of AC6-PI. The structure of SiAC-PI was characterized by FTIR spectra, crosslinked density and XRD diffraction patterns.
2019, 30(3): 714-716
doi: 10.1016/j.cclet.2018.11.013
Abstract:
As trifluoromethylthiolation has received increasing attention recently, many CF3S-reagents and trifluoromethylthiolation methods have been developed. Herein we describe trifluoromethylthiolation of alkyl halides by using Ph3P+CF2CO2- as a fluoride and difluorocarbene source. Difluorocarbene is a versatile intermediate, but its side reactions are usually ignored and the by-products would therefore be discarded. In this work, a side reaction of difluorocarbene, the generation of a fluoride anion from difluorocarbene, was developed into a synthetic tool. Although the trifluoromethylthiolation reaction involved multi-sequential steps, the cleavage of C-F bond, the formation of CF2=S bond, F-C(S)F2 bond, and C-SCF3 bond, the conversion proceeded fast and was completed within 10 min.
As trifluoromethylthiolation has received increasing attention recently, many CF3S-reagents and trifluoromethylthiolation methods have been developed. Herein we describe trifluoromethylthiolation of alkyl halides by using Ph3P+CF2CO2- as a fluoride and difluorocarbene source. Difluorocarbene is a versatile intermediate, but its side reactions are usually ignored and the by-products would therefore be discarded. In this work, a side reaction of difluorocarbene, the generation of a fluoride anion from difluorocarbene, was developed into a synthetic tool. Although the trifluoromethylthiolation reaction involved multi-sequential steps, the cleavage of C-F bond, the formation of CF2=S bond, F-C(S)F2 bond, and C-SCF3 bond, the conversion proceeded fast and was completed within 10 min.
2019, 30(3): 717-720
doi: 10.1016/j.cclet.2018.08.017
Abstract:
Based on the reversible host-guest inclusion/exclusion of cyclodextrin-functionalized graphene oxide (GO-CD) and azobenzene-terminated polyhedral oligomeric silsesquioxane (Azo-POSS), a novel kind of light-responsive nanocomposites GO-POSS was developed under mild condition. 1H NMR, FT-IR, TG, TEM and UV-vis spectroscopy were conducted to characterize the chemical composition and photoresponsive performance of obtained GO-POSS nanocomposites. The results demonstrated that nanocagestructured POSS and nanosheet GO components in GO-POSS exhibited pronounced supramolecular assembly/disassembly behavior upon UV/vis irradiation. Moreover, GO-POSS nanocomposites showed good water dispersity and had remarkable impact on oxygen permeability of conventional PVA-coated films under varied light irradiation conditions, which would be valuable for developing smart gas barrier materials in packaging.
Based on the reversible host-guest inclusion/exclusion of cyclodextrin-functionalized graphene oxide (GO-CD) and azobenzene-terminated polyhedral oligomeric silsesquioxane (Azo-POSS), a novel kind of light-responsive nanocomposites GO-POSS was developed under mild condition. 1H NMR, FT-IR, TG, TEM and UV-vis spectroscopy were conducted to characterize the chemical composition and photoresponsive performance of obtained GO-POSS nanocomposites. The results demonstrated that nanocagestructured POSS and nanosheet GO components in GO-POSS exhibited pronounced supramolecular assembly/disassembly behavior upon UV/vis irradiation. Moreover, GO-POSS nanocomposites showed good water dispersity and had remarkable impact on oxygen permeability of conventional PVA-coated films under varied light irradiation conditions, which would be valuable for developing smart gas barrier materials in packaging.
2019, 30(3): 721-724
doi: 10.1016/j.cclet.2018.12.015
Abstract:
We report here a one-pot synthetic method for the synthesis of a bisester-functionalized copillar[5]arene (BECP5A) with yield up to 20%. The properties of BECP5A in solution and in solid state were deeply investigated with the aid of 1D and 2D NMR spectra and X-ray diffraction, showing that this molecule has a fully self-included conformation in chloroform and partial self-inclusion in DMSO, and the compound has an asymmetrical structure with only one self-included side in the cavity of pillar[5]arene in the solid state. This compound will be used as the precursor of complex systems such as polymers and mechanically interlocked molecules.
We report here a one-pot synthetic method for the synthesis of a bisester-functionalized copillar[5]arene (BECP5A) with yield up to 20%. The properties of BECP5A in solution and in solid state were deeply investigated with the aid of 1D and 2D NMR spectra and X-ray diffraction, showing that this molecule has a fully self-included conformation in chloroform and partial self-inclusion in DMSO, and the compound has an asymmetrical structure with only one self-included side in the cavity of pillar[5]arene in the solid state. This compound will be used as the precursor of complex systems such as polymers and mechanically interlocked molecules.
2019, 30(3): 725-728
doi: 10.1016/j.cclet.2018.11.025
Abstract:
An efficient method for preparation of substituted 1, 2-phenylenedimethanols and aliphatic 1, 4-diols that are valuable intermediates in organic synthesis, has been developed by the base-promoted reduction of isobenzofuran-1(3H)-ones and γ-lactones with silane under mild conditions. Compared with traditional procedures using stoichiometric amounts of metal hydrides and alkyl reductants, the present method avoids the use of sensitive reagents and is operationally simple and a broad variety of functional groups are tolerated.
An efficient method for preparation of substituted 1, 2-phenylenedimethanols and aliphatic 1, 4-diols that are valuable intermediates in organic synthesis, has been developed by the base-promoted reduction of isobenzofuran-1(3H)-ones and γ-lactones with silane under mild conditions. Compared with traditional procedures using stoichiometric amounts of metal hydrides and alkyl reductants, the present method avoids the use of sensitive reagents and is operationally simple and a broad variety of functional groups are tolerated.
2019, 30(3): 729-734
doi: 10.1016/j.cclet.2018.08.014
Abstract:
In this work, a spherical hollow mesoporous silica (SHMS) with high surface area (902 m2/g) and large mesopore volume (1.31 cm3/g) was prepared via a facile and scalable two-step soft-hard dual templateassisted sol-gel approach (OSDSG) by using glucose-derived carbon nano/micro particles (NMCP) as a hard template and cetyltrimethylammonium bromide (CTAB) as a soft template, respectively, in which the size-preselected carbon submicro-particle was used to replace ploymer sphere, and no extra precious additives like n-octadecyltrimethoxysilane (C18TMS). Supported phosphotungstic acid (PTA) catalysts on SHMS (PTA/SHMS) and on previously reported spherical mesoporous silica (PTA/SMS) with 25 wt% of PTA loading were prepared and employed as solid acid catalysts for diverse reactions. Transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD), and NH3 temperatureprogrammed desorption (NH3-TPD) techniques were employed to characterize the nature of carriers and supported PTA catalysts for revealing the structure-performance relationship. The developed PTA/ SHMS catalyst demonstrates much higher catalytic activity than PTA/SMS for diverse reactions including alkenylation, esterification, alkylation, and benzylation, ascribed to the strengthened mass transfer and enlarged exposure degree of acidic sites to reactants those resulting from unique hollow and mesoporous morphology. Moreover, PTA/SHMS catalyst also exhibits outstanding catalytic performance for the diverse α-arylstyrenes via solid acid-mediated alkenylation. PTA/SHMS could be considered as a practical solid acid catalyst for diverse transformations.
In this work, a spherical hollow mesoporous silica (SHMS) with high surface area (902 m2/g) and large mesopore volume (1.31 cm3/g) was prepared via a facile and scalable two-step soft-hard dual templateassisted sol-gel approach (OSDSG) by using glucose-derived carbon nano/micro particles (NMCP) as a hard template and cetyltrimethylammonium bromide (CTAB) as a soft template, respectively, in which the size-preselected carbon submicro-particle was used to replace ploymer sphere, and no extra precious additives like n-octadecyltrimethoxysilane (C18TMS). Supported phosphotungstic acid (PTA) catalysts on SHMS (PTA/SHMS) and on previously reported spherical mesoporous silica (PTA/SMS) with 25 wt% of PTA loading were prepared and employed as solid acid catalysts for diverse reactions. Transmission electron microscopy (TEM), N2 adsorption-desorption, X-ray diffraction (XRD), and NH3 temperatureprogrammed desorption (NH3-TPD) techniques were employed to characterize the nature of carriers and supported PTA catalysts for revealing the structure-performance relationship. The developed PTA/ SHMS catalyst demonstrates much higher catalytic activity than PTA/SMS for diverse reactions including alkenylation, esterification, alkylation, and benzylation, ascribed to the strengthened mass transfer and enlarged exposure degree of acidic sites to reactants those resulting from unique hollow and mesoporous morphology. Moreover, PTA/SHMS catalyst also exhibits outstanding catalytic performance for the diverse α-arylstyrenes via solid acid-mediated alkenylation. PTA/SHMS could be considered as a practical solid acid catalyst for diverse transformations.
2019, 30(3): 735-738
doi: 10.1016/j.cclet.2018.08.020
Abstract:
A novel ZnCo2O4/Bi2O3 heterojunction photocatalyst was prepared, and the formation of the heterojunction was confirmed via HRTEM. Photocatalytic activity of as-prepared samples was evaluated through photodegradation of malachite green (MG). The degradation results show that the as-prepared 13% ZnCo2O4/Bi2O3 heterojunction photocatalyst exhibits higher activity than pure Bi2O3. The MG degradation rate for the as-prepared catalyst is as high as 94%. The enhanced photocatalytic activity is mainly attributed to the broad photoabsorption and low recombination rate of photogenerated electronhole pairs, which is driven by the photogenerated potential difference formed at the ZnCo2O4/Bi2O3 heterojunction interface.
A novel ZnCo2O4/Bi2O3 heterojunction photocatalyst was prepared, and the formation of the heterojunction was confirmed via HRTEM. Photocatalytic activity of as-prepared samples was evaluated through photodegradation of malachite green (MG). The degradation results show that the as-prepared 13% ZnCo2O4/Bi2O3 heterojunction photocatalyst exhibits higher activity than pure Bi2O3. The MG degradation rate for the as-prepared catalyst is as high as 94%. The enhanced photocatalytic activity is mainly attributed to the broad photoabsorption and low recombination rate of photogenerated electronhole pairs, which is driven by the photogenerated potential difference formed at the ZnCo2O4/Bi2O3 heterojunction interface.
2019, 30(3): 739-742
doi: 10.1016/j.cclet.2018.09.008
Abstract:
Fragranced products are wildly used in our daily life. However, their storage, application and quality are severely influenced by their strong volatility. In order to overcome these natural defects of fragrances, fragrance encapsulation approaches have been developed recently. In this study, a mild, simple and lowcost method of fragrance encapsulation was invented. Liposomes composed of soya lecithin/DSPEPEG2000/PLGA were prepared to encapsulate lily fragrance (LF). And these nanosized fragrance products was named LF-NPs. The hydrodynamic diameters of LF-NPs were approximately 100 nm and their encapsulation efficiency was up to 21.9%. Besides, LF-NPs could also prolong the release time of lily fragrance. Finally, the cytotoxicity tests indicated that LF-NPs offered biocompatibility. Therefore, LF-NPs were expected to have application prospects.
Fragranced products are wildly used in our daily life. However, their storage, application and quality are severely influenced by their strong volatility. In order to overcome these natural defects of fragrances, fragrance encapsulation approaches have been developed recently. In this study, a mild, simple and lowcost method of fragrance encapsulation was invented. Liposomes composed of soya lecithin/DSPEPEG2000/PLGA were prepared to encapsulate lily fragrance (LF). And these nanosized fragrance products was named LF-NPs. The hydrodynamic diameters of LF-NPs were approximately 100 nm and their encapsulation efficiency was up to 21.9%. Besides, LF-NPs could also prolong the release time of lily fragrance. Finally, the cytotoxicity tests indicated that LF-NPs offered biocompatibility. Therefore, LF-NPs were expected to have application prospects.
2019, 30(3): 743-746
doi: 10.1016/j.cclet.2018.09.003
Abstract:
Ubiquitin-propargylamide (Ub-PA) is one of the most widely used activity-based probe to measure the activity of deubiquitinases (DUBs) and help validate DUBs targeting inhibitors. However, current synthetic route of Ub-PA is cumbersome. In this work, we report a novel semi-synthetic strategy to prepare Ub-PA in large-scale. Biochemical assays prove that semi-synthetic Ub-PA is an effective probe in identifying DUBs targeting inhibitors.
Ubiquitin-propargylamide (Ub-PA) is one of the most widely used activity-based probe to measure the activity of deubiquitinases (DUBs) and help validate DUBs targeting inhibitors. However, current synthetic route of Ub-PA is cumbersome. In this work, we report a novel semi-synthetic strategy to prepare Ub-PA in large-scale. Biochemical assays prove that semi-synthetic Ub-PA is an effective probe in identifying DUBs targeting inhibitors.
2019, 30(3): 747-749
doi: 10.1016/j.cclet.2018.09.015
Abstract:
Fragrances are widely used in our daily life and have made great contributions to creating a clean and fresh healthy air environment. However, the rapid volatilization severely influences their storage, application and quality. Therefore, it is necessary and urgent to develop approaches to controllably release the odorants as demanded. In this study, photo-driven mesoporous silica nanospheres loaded with sandela 803 was designed, prepared and named as S803@MS-S. S803@MS-S possessed ordered mesoporous, large specific surface area and pore volume. After adsorption of sandela 803, the S803@MSS was added into wallpaper to prepare fragrant wallpaper S803@MS-S-W. And this wallpaper exhibited excellent sustained and controlled release performances stimulated by light.
Fragrances are widely used in our daily life and have made great contributions to creating a clean and fresh healthy air environment. However, the rapid volatilization severely influences their storage, application and quality. Therefore, it is necessary and urgent to develop approaches to controllably release the odorants as demanded. In this study, photo-driven mesoporous silica nanospheres loaded with sandela 803 was designed, prepared and named as S803@MS-S. S803@MS-S possessed ordered mesoporous, large specific surface area and pore volume. After adsorption of sandela 803, the S803@MSS was added into wallpaper to prepare fragrant wallpaper S803@MS-S-W. And this wallpaper exhibited excellent sustained and controlled release performances stimulated by light.
2019, 30(3): 750-756
doi: 10.1016/j.cclet.2018.09.013
Abstract:
All-solid-state flexible supercapacitors have shown great potential in wearable and portable electronics. In this work, a flexible asymmetric pseudocapacitor (FAPC) is fabricated by using MnO2 nanosheetscarbon fabric as cathode and Fe2O3 nanowire-carbon fabric as anode in the presence of PVA-LiCl as gel electrolyte. With high area capacitances of MnO2 and Fe2O3 based electrodes by optimizing the reaction conditions, the device shows high working potential of 1.8 V, high area capacitance of 83.3 mF/cm2 (119 F/g), stable cycling performance with 82.3% of capacitance retention after 5000 cycles, and a competitive energy density of 53.55 Wh/kg in the broader context of MnO2-based supercapacitors. In addition, the FAPC demonstrates excellent mechanical stability and flexibility with negligible degradation of electrochemical performance after numerous bending tests, establishing it as a promising candidate for portable and wearable energy storage.
All-solid-state flexible supercapacitors have shown great potential in wearable and portable electronics. In this work, a flexible asymmetric pseudocapacitor (FAPC) is fabricated by using MnO2 nanosheetscarbon fabric as cathode and Fe2O3 nanowire-carbon fabric as anode in the presence of PVA-LiCl as gel electrolyte. With high area capacitances of MnO2 and Fe2O3 based electrodes by optimizing the reaction conditions, the device shows high working potential of 1.8 V, high area capacitance of 83.3 mF/cm2 (119 F/g), stable cycling performance with 82.3% of capacitance retention after 5000 cycles, and a competitive energy density of 53.55 Wh/kg in the broader context of MnO2-based supercapacitors. In addition, the FAPC demonstrates excellent mechanical stability and flexibility with negligible degradation of electrochemical performance after numerous bending tests, establishing it as a promising candidate for portable and wearable energy storage.
2019, 30(3): 757-761
doi: 10.1016/j.cclet.2018.09.016
Abstract:
In our present work, the high-silica hierarchical porous ZSM-5 with appropriate Brönsted acidity and hierarchical porous structure was synthesized by sol-gel method for continuously catalytic conversion of benzene alkylation with methanol to xylene. The effects of temperature, pressure, benzene/methanol molar ratio and weight hour space velocity (WHSV) on the catalytic performance of the catalyst were investigated as well. As a result, the high-silica hierarchical porous ZSM-5 showed great performance as the yield of xylene was up to 41.1% under the optimum reaction conditions (500℃, 0.1 MPa, Mbenzene/Mmethanol=1:1.5 and WHSV=4 h-1), while the selectivity to by-product, ethylbenzene, was well suppressed (below 0.1%). In addition, the catalyst structure and properties were characterized by the means of XRD, IR, TPD, SEM, TEM and N2 physical adsorption technologies.
In our present work, the high-silica hierarchical porous ZSM-5 with appropriate Brönsted acidity and hierarchical porous structure was synthesized by sol-gel method for continuously catalytic conversion of benzene alkylation with methanol to xylene. The effects of temperature, pressure, benzene/methanol molar ratio and weight hour space velocity (WHSV) on the catalytic performance of the catalyst were investigated as well. As a result, the high-silica hierarchical porous ZSM-5 showed great performance as the yield of xylene was up to 41.1% under the optimum reaction conditions (500℃, 0.1 MPa, Mbenzene/Mmethanol=1:1.5 and WHSV=4 h-1), while the selectivity to by-product, ethylbenzene, was well suppressed (below 0.1%). In addition, the catalyst structure and properties were characterized by the means of XRD, IR, TPD, SEM, TEM and N2 physical adsorption technologies.
2019, 30(3): 762-766
doi: 10.1016/j.cclet.2018.11.005
Abstract:
The adsorption properties of the Pb(Ⅱ)-Cd(Ⅱ) double-imprinted electrospun crosslinked chitosan nanofibers (Pd/Cd-DIECCNs) prepared by electropspinning and imprinting process for the removal of Pb (Ⅱ) and Cd(Ⅱ) from aqueous solutions were investigated. The prepared nanofibers were characterized by scanning electron microscope (SEM) analysis. Under the optimum experimental conditions, the minimum fiber average diameter was obtained 110 nm. Then the adsorption experiments were carried out to study the effect of different adsorption parameters, such as pH, the ratio between Pb(Ⅱ) and Cd(Ⅱ) in the mixed solutions, contact time, the Pd/Cd-DIECCNs dose and temperature in a batch system. The Extended Langmuir model was applied to describe the equilibrium data of Pb(Ⅱ) and Cd(Ⅱ). The maximum adsorption capacities of the Pd/Cd-DIECCNs arrived at 567 mg/g for Pb(Ⅱ) and 341 mg/g for Cd (Ⅱ), respectively.
The adsorption properties of the Pb(Ⅱ)-Cd(Ⅱ) double-imprinted electrospun crosslinked chitosan nanofibers (Pd/Cd-DIECCNs) prepared by electropspinning and imprinting process for the removal of Pb (Ⅱ) and Cd(Ⅱ) from aqueous solutions were investigated. The prepared nanofibers were characterized by scanning electron microscope (SEM) analysis. Under the optimum experimental conditions, the minimum fiber average diameter was obtained 110 nm. Then the adsorption experiments were carried out to study the effect of different adsorption parameters, such as pH, the ratio between Pb(Ⅱ) and Cd(Ⅱ) in the mixed solutions, contact time, the Pd/Cd-DIECCNs dose and temperature in a batch system. The Extended Langmuir model was applied to describe the equilibrium data of Pb(Ⅱ) and Cd(Ⅱ). The maximum adsorption capacities of the Pd/Cd-DIECCNs arrived at 567 mg/g for Pb(Ⅱ) and 341 mg/g for Cd (Ⅱ), respectively.
2019, 30(3): 767-770
doi: 10.1016/j.cclet.2018.09.019
Abstract:
Tetrathiafulvalene (TTF), as a classical building unit, has attracted considerable attention, especially its functional derivatives. Hydrogen bonding (H-bonding) networks are a class of traditional and stable nanostructures, which play an important role in two-dimensional self-assembly and multi-component co-assembly. In this paper, we studied the regulation of H-bonding networks by functional groups in TTF derivatives. The results indicate that the position of pyridine on TTF not only affects their self-assembly structures in different solvents, but also controls the H-bonding networks through different mechanisms. Both para-TTF and meta-TTF molecules show different co-assembled structures with solvents depending on whether or not the presence of carboxylic acid group. On the pre-prepared H-bonding networks formed by famous 1, 3, 5-tris(10-carboxydecyloxy)-benzene (TCDB) molecule, both para-TTF and meta-TTF disturbed the original network structures with different degree of TCDB deformation. The formed new H-bonding networks with or without TTF derivatives participation are mainly attributed to the position of pyridine in TTF-based molecules. These results would be important for design of exceptional and functional nanostructures starting with the design of building block.
Tetrathiafulvalene (TTF), as a classical building unit, has attracted considerable attention, especially its functional derivatives. Hydrogen bonding (H-bonding) networks are a class of traditional and stable nanostructures, which play an important role in two-dimensional self-assembly and multi-component co-assembly. In this paper, we studied the regulation of H-bonding networks by functional groups in TTF derivatives. The results indicate that the position of pyridine on TTF not only affects their self-assembly structures in different solvents, but also controls the H-bonding networks through different mechanisms. Both para-TTF and meta-TTF molecules show different co-assembled structures with solvents depending on whether or not the presence of carboxylic acid group. On the pre-prepared H-bonding networks formed by famous 1, 3, 5-tris(10-carboxydecyloxy)-benzene (TCDB) molecule, both para-TTF and meta-TTF disturbed the original network structures with different degree of TCDB deformation. The formed new H-bonding networks with or without TTF derivatives participation are mainly attributed to the position of pyridine in TTF-based molecules. These results would be important for design of exceptional and functional nanostructures starting with the design of building block.
2019, 30(3): 771-774
doi: 10.1016/j.cclet.2018.10.006
Abstract:
In this study, SnNb2O6 and Sn2Nb2O7 nanosheets are synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. The SnNb2O6 electrode exhibits high reversible capacity and excellent cycling stability (498 mAh/g at 0.1 A/g after 100 cycles), which is superior to that of Sn2Nb2O7 electrode (173 mAh/g at 0.1 A/g after 100 cycles). Even increasing the current density to 2.0 A/g, the SnNb2O6 electrode still delivers a reversible capacity up to 306 mA h/g. The rate performance of the SnNb2O6 electrode is also better than that of Sn2Nb2O7 electrode at different current densities from 0.1 A/g to 2.0 A/g. The enhanced electrochemical performance of SnNb2O6 nanosheets can be attributed to the unique layered structure, which is conducive to the diffusion of the lithium ions and the migration of electrons during discharge/charge.
In this study, SnNb2O6 and Sn2Nb2O7 nanosheets are synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. The SnNb2O6 electrode exhibits high reversible capacity and excellent cycling stability (498 mAh/g at 0.1 A/g after 100 cycles), which is superior to that of Sn2Nb2O7 electrode (173 mAh/g at 0.1 A/g after 100 cycles). Even increasing the current density to 2.0 A/g, the SnNb2O6 electrode still delivers a reversible capacity up to 306 mA h/g. The rate performance of the SnNb2O6 electrode is also better than that of Sn2Nb2O7 electrode at different current densities from 0.1 A/g to 2.0 A/g. The enhanced electrochemical performance of SnNb2O6 nanosheets can be attributed to the unique layered structure, which is conducive to the diffusion of the lithium ions and the migration of electrons during discharge/charge.
2019, 30(3): 775-778
doi: 10.1016/j.cclet.2018.10.005
Abstract:
CuY zeolite is a promising catalyst in the field of manufacturing dimethyl carbonate (DMC) through oxidative carbonylation of methanol. Cu+ exchanged with Brønsted acid sites are supposed to be active for this reaction. However, the location of Cu+ in small cages can not interact with reactants because of steric hindrance, which lead to a waste of Cu species. In this work, NH4F solution was used to modify the pore structure of zeolite Y by etching the framework T atoms. Physical and chemical adsorption of probe molecules with different size are used to determine the changes of porosity as well as the accessibility of Cu+ sites. At an optimized etching time, the small cages were opened with maintained zeolitic framework. As a result, more Cu+ species located in small cages become accessible to reactants, which contributes to the enhanced activity in this reaction.
CuY zeolite is a promising catalyst in the field of manufacturing dimethyl carbonate (DMC) through oxidative carbonylation of methanol. Cu+ exchanged with Brønsted acid sites are supposed to be active for this reaction. However, the location of Cu+ in small cages can not interact with reactants because of steric hindrance, which lead to a waste of Cu species. In this work, NH4F solution was used to modify the pore structure of zeolite Y by etching the framework T atoms. Physical and chemical adsorption of probe molecules with different size are used to determine the changes of porosity as well as the accessibility of Cu+ sites. At an optimized etching time, the small cages were opened with maintained zeolitic framework. As a result, more Cu+ species located in small cages become accessible to reactants, which contributes to the enhanced activity in this reaction.
2019, 30(3): 779-782
doi: 10.1016/j.cclet.2018.10.019
Abstract:
By taking advantage of recent advances in aptamer biology and nanotechnology, we developed a general approach for the design and fabrication of bioresponsive controlled delivery systems. It utilized the structure-switchable aptamer directed assembly and disassembly of gold nanoparticles from mesoporous silica supports, which enables the control of cargo release from the inside of the mesoporous nanoparticles specifically in the presence of target molecule.
By taking advantage of recent advances in aptamer biology and nanotechnology, we developed a general approach for the design and fabrication of bioresponsive controlled delivery systems. It utilized the structure-switchable aptamer directed assembly and disassembly of gold nanoparticles from mesoporous silica supports, which enables the control of cargo release from the inside of the mesoporous nanoparticles specifically in the presence of target molecule.
2019, 30(3): 783-786
doi: 10.1016/j.cclet.2018.10.036
Abstract:
Three-dimensional (3D) navel-like Bi2WO6 (BWO) hierarchical microspheres (HMSs) were successfully prepared using a simple hydrothermal method. The as-obtained BWO samples were characterized by a variety of techniques. XRD result indicated that the as-synthesized samples were well-crystallized orthorhombic phase Bi2WO6 structure. SEM observations revealed that the hierarchical microspheres with an average diameter of 2 μm were built from several dozen of nanosheets. UV-vis diffuse reflectance spectrum study revealed that the obtained BWO sample had band gap energy of about 3.3 eV. Photoluminescence (PL) result showed that the sample had weak emission intensity. The BET specific surface area of the BWO sample was about 35.40 m2/g. The photocatalytic efficiency of the as-obtained BWO was evaluated by the degradation of norfloxacin (NOR) antibiotic. The result showed an about 67% NOR degradation in 8 h.
Three-dimensional (3D) navel-like Bi2WO6 (BWO) hierarchical microspheres (HMSs) were successfully prepared using a simple hydrothermal method. The as-obtained BWO samples were characterized by a variety of techniques. XRD result indicated that the as-synthesized samples were well-crystallized orthorhombic phase Bi2WO6 structure. SEM observations revealed that the hierarchical microspheres with an average diameter of 2 μm were built from several dozen of nanosheets. UV-vis diffuse reflectance spectrum study revealed that the obtained BWO sample had band gap energy of about 3.3 eV. Photoluminescence (PL) result showed that the sample had weak emission intensity. The BET specific surface area of the BWO sample was about 35.40 m2/g. The photocatalytic efficiency of the as-obtained BWO was evaluated by the degradation of norfloxacin (NOR) antibiotic. The result showed an about 67% NOR degradation in 8 h.
2019, 30(3): 787-791
doi: 10.1016/j.cclet.2018.11.003
Abstract:
In this work, nitrogen doped clews-like carbon materials were successfully fabricated through hydrothermal polymerization method, followed by post treatment that integrated the carbonization, activation and post-nitrogen doping into one process. This preparation method can form particular hierarchical porous structure without using any sacrificial templates. The experimental results show that the nitrogen doped clews-like hierarchical porous carbon materials possess a relatively high specific surface area of 815 m2/g with the nitrogen content of 10.58 at%. The electrochemical properties show that the resulting sample delivers 258 F/g at a 0.5 A/g and excellent capacity retention of 79% at 20 A/g. After conducting 10, 000 charge-discharge cycles at 10 A/g, the capacitance retention of 98.3% is achieved. These intriguing results demonstrate that the obtained nitrogen doped clews-like carbon materials will be promising electrode materials for supercapacitor and other energy storage devices.
In this work, nitrogen doped clews-like carbon materials were successfully fabricated through hydrothermal polymerization method, followed by post treatment that integrated the carbonization, activation and post-nitrogen doping into one process. This preparation method can form particular hierarchical porous structure without using any sacrificial templates. The experimental results show that the nitrogen doped clews-like hierarchical porous carbon materials possess a relatively high specific surface area of 815 m2/g with the nitrogen content of 10.58 at%. The electrochemical properties show that the resulting sample delivers 258 F/g at a 0.5 A/g and excellent capacity retention of 79% at 20 A/g. After conducting 10, 000 charge-discharge cycles at 10 A/g, the capacitance retention of 98.3% is achieved. These intriguing results demonstrate that the obtained nitrogen doped clews-like carbon materials will be promising electrode materials for supercapacitor and other energy storage devices.
2019, 30(3): 792-796
doi: 10.1016/j.cclet.2018.11.004
Abstract:
The nominal Li3-xFe2-xTix(PO4)2.55(VO4)0.45 (x=0~0.3) compounds were synthesized by a sol-gel process. Different from the single VO43- doping, further introduction of Ti4+ ion was easy to result in precipitation of a little secondary phases, besides the main NASICON products. The simultaneous substitution of Ti4+ and VO43- for Fe3+ and PO43-, respectively, in the Li3Fe2(PO4)3 resulted in a net improvement in the rate capability and cycling performance, as compared with the single Ti4+ or VO43--substituted compound. The sample with x=0.2 presented a high initial discharging capacity of 125.4 mAh/g at the rate of 0.5C, about 25% higher than the Ti4+-substituted Li2.8Fe1.8Ti0.2(PO4)3, and 102.6 mAh/g after 60 cycles at 2C, about 12% higher than the single VO43--substituted one. The high rate performance between 0.5C to 10C suggested that this sample had a good stability and reversibility. These results proved that the combination of the Ti4+ substitution for Fe3+ with the VO43- substitution for PO43- was a promising method of improving electrochemical performance of the studied Li3Fe2(PO4)3 cathode material.
The nominal Li3-xFe2-xTix(PO4)2.55(VO4)0.45 (x=0~0.3) compounds were synthesized by a sol-gel process. Different from the single VO43- doping, further introduction of Ti4+ ion was easy to result in precipitation of a little secondary phases, besides the main NASICON products. The simultaneous substitution of Ti4+ and VO43- for Fe3+ and PO43-, respectively, in the Li3Fe2(PO4)3 resulted in a net improvement in the rate capability and cycling performance, as compared with the single Ti4+ or VO43--substituted compound. The sample with x=0.2 presented a high initial discharging capacity of 125.4 mAh/g at the rate of 0.5C, about 25% higher than the Ti4+-substituted Li2.8Fe1.8Ti0.2(PO4)3, and 102.6 mAh/g after 60 cycles at 2C, about 12% higher than the single VO43--substituted one. The high rate performance between 0.5C to 10C suggested that this sample had a good stability and reversibility. These results proved that the combination of the Ti4+ substitution for Fe3+ with the VO43- substitution for PO43- was a promising method of improving electrochemical performance of the studied Li3Fe2(PO4)3 cathode material.
2019, 30(3): 797-800
doi: 10.1016/j.cclet.2018.11.011
Abstract:
In present study, double-jet precipitation method was employed to prepare the uniform AgX (X: Cl, Br, I) colloids, and then ascorbic acid/sodium borohydride was respectively used to reduce AgX into the silver nanoparticles (Ag NPs). The main experimental parameters about above two processes were investigated. It was found that under the same synthesis conditions the size of obtained Ag NPS was strongly dependent on the AgX size, and the silver particles obtained by reduction of AgCl, AgBr and AgI had the monotonously diminishing size order. SEM, TEM, XRD, and UV spectrometry were employed to characterize the obtained AgX and Ag NPs respectively, and they gave the size variation clearly and the mechanism was discussed.
In present study, double-jet precipitation method was employed to prepare the uniform AgX (X: Cl, Br, I) colloids, and then ascorbic acid/sodium borohydride was respectively used to reduce AgX into the silver nanoparticles (Ag NPs). The main experimental parameters about above two processes were investigated. It was found that under the same synthesis conditions the size of obtained Ag NPS was strongly dependent on the AgX size, and the silver particles obtained by reduction of AgCl, AgBr and AgI had the monotonously diminishing size order. SEM, TEM, XRD, and UV spectrometry were employed to characterize the obtained AgX and Ag NPs respectively, and they gave the size variation clearly and the mechanism was discussed.
2019, 30(3): 801-805
doi: 10.1016/j.cclet.2018.12.009
Abstract:
Three cadmium(Ⅱ) metal-organic frameworks (MOFs) based on tetracarboxylate ligands, namely [Cd2(TTTA)(DMF)3] 2DMF (1), [Cd2(TB)(H2O)4] 3DMF H2O (2) and [Cd(TEB)0.5] 2DMF 4H2O (3) have been designed and synthesized. Complex 1 is a 2-dimensional (2D) 3, 4-connected network with 3, 4L13 topology, complex 2 features a 3-dimensional (3D) 3, 4-connected tfa topology with a 2-fold interpenetrating structure and complex 3 has a 3D 4-connected dia topology with a 4-fold interpenetrating structure. Interestingly, 2 exhibits permanent pores and selective adsorption of CO2 over CH4. In addition, 2 shows fluorescence sensing of Fe3+ ion and rapid detection of nitroaromatic compounds (NACs) through fluorescence quenching.
Three cadmium(Ⅱ) metal-organic frameworks (MOFs) based on tetracarboxylate ligands, namely [Cd2(TTTA)(DMF)3] 2DMF (1), [Cd2(TB)(H2O)4] 3DMF H2O (2) and [Cd(TEB)0.5] 2DMF 4H2O (3) have been designed and synthesized. Complex 1 is a 2-dimensional (2D) 3, 4-connected network with 3, 4L13 topology, complex 2 features a 3-dimensional (3D) 3, 4-connected tfa topology with a 2-fold interpenetrating structure and complex 3 has a 3D 4-connected dia topology with a 4-fold interpenetrating structure. Interestingly, 2 exhibits permanent pores and selective adsorption of CO2 over CH4. In addition, 2 shows fluorescence sensing of Fe3+ ion and rapid detection of nitroaromatic compounds (NACs) through fluorescence quenching.
2019, 30(3): 806-808
doi: 10.1016/j.cclet.2018.12.010
Abstract:
Zn3V3O8 two-dimensional micro sheets are successfully synthesized by combination of solvothermal method and heat treatment. The X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM) are used to characterize the structure and morphology of the samples, and the battery testing system is used to investigate its electrochemical performance. The results show that the Zn3V3O8 is successfully obtained using mix solvent (water:ethylene glycol=1:1), and the sample takes on morphology of two-dimensional sheets. The initial discharge capacity for Zn3V3O8 two-dimensional micro sheets is 752.0 mAh/g at 100 mA/g in the voltage range of 0.01-3 V. After heat treatment in a tube furnace at 550℃, the sample had the initial discharge capacity as 1152.0 mAh/g and maintained it at 901.4 mAh/g after 100 cycles. The good electrochemical performance for Zn3V3O8 two-dimensional micro sheets make it possible to be used as novel anode for lithium ion battery application.
Zn3V3O8 two-dimensional micro sheets are successfully synthesized by combination of solvothermal method and heat treatment. The X-ray diffraction (XRD) and field emission scanning electron microscopy (SEM) are used to characterize the structure and morphology of the samples, and the battery testing system is used to investigate its electrochemical performance. The results show that the Zn3V3O8 is successfully obtained using mix solvent (water:ethylene glycol=1:1), and the sample takes on morphology of two-dimensional sheets. The initial discharge capacity for Zn3V3O8 two-dimensional micro sheets is 752.0 mAh/g at 100 mA/g in the voltage range of 0.01-3 V. After heat treatment in a tube furnace at 550℃, the sample had the initial discharge capacity as 1152.0 mAh/g and maintained it at 901.4 mAh/g after 100 cycles. The good electrochemical performance for Zn3V3O8 two-dimensional micro sheets make it possible to be used as novel anode for lithium ion battery application.
