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2020 Volume 83 Issue 2
Blue Light-Emitting d8 Metal Complexes Supported by Tetradentate Ligands and Their OLED Applications
2020, 83(2): 99-104
Abstract:
Red and green phosphorescent metal complexes in OLEDs have shown performances that meet the practical industrial applications in terms of device efficiency and stability, whereas the applications of blue phosphorescent metal complexes have been hampered by their unsatisfactory stability. High energy of the excited states and thermal population of d-d states are conceived to cause the decomposition of blue light-emitting complexes. The development of d8 blue phosphorescent transition metal complexes by using tetradentate ligand is expected to enhance the emission efficiency and stability simultaneously. Progress in blue light-emitting platinum(Ⅱ) and palladium(Ⅱ) complexes and their performances in OLEDs is reviewed. By shedding light on the ligand structures-photophysical and stability relationships, we try to provide suggestions to the future effort for developing blue light-emitting metal complexes.
Red and green phosphorescent metal complexes in OLEDs have shown performances that meet the practical industrial applications in terms of device efficiency and stability, whereas the applications of blue phosphorescent metal complexes have been hampered by their unsatisfactory stability. High energy of the excited states and thermal population of d-d states are conceived to cause the decomposition of blue light-emitting complexes. The development of d8 blue phosphorescent transition metal complexes by using tetradentate ligand is expected to enhance the emission efficiency and stability simultaneously. Progress in blue light-emitting platinum(Ⅱ) and palladium(Ⅱ) complexes and their performances in OLEDs is reviewed. By shedding light on the ligand structures-photophysical and stability relationships, we try to provide suggestions to the future effort for developing blue light-emitting metal complexes.
2020, 83(2): 105-110
Abstract:
In this mini-review, we have briefly summarized the theoretical research on geometrical structures and coordination chemistry of actinide complexes, the electronic structures of actinyl-crown-ether complexes, and the basic principle for chemical bonding of actinyl complexes. Although increasingly numerous spectroscopy and crystallography data had been available experimentally, there were lack of systematic investigations on theoretically electronic structure and chemical bonding of actinide complexes. Herein reviewed are our recently works from computational chemistry modeling on the coordination structures, stabilization energies and spectra properties of actinyl-crown-ether complexes. Our research has shown that the in-cavity complexes and their bonding features between (thio)-crown ethers and f-elements exhibit conventional conformations, with typical An≡Oactinyl and An-Oligand and An-Sligand distances. The typical ionic An-Oligand and An-Sligand bonds with an extent of covalent interaction between the An and ligand donor atoms primarily attributable to the overlap degree of radial distribution of valence atomic orbitals. From U to Cm, LMCT is gradually significant, resulting in the decrease of the formal oxidation state of Am and Cm, and the weakening of the interaction between metal ions and ligands. This periodicity of chemical bonding and the metal oxidation state provide fundamental guidance for the design of reasonable and efficient ligands in the application of lanthanide-actinide separation.
In this mini-review, we have briefly summarized the theoretical research on geometrical structures and coordination chemistry of actinide complexes, the electronic structures of actinyl-crown-ether complexes, and the basic principle for chemical bonding of actinyl complexes. Although increasingly numerous spectroscopy and crystallography data had been available experimentally, there were lack of systematic investigations on theoretically electronic structure and chemical bonding of actinide complexes. Herein reviewed are our recently works from computational chemistry modeling on the coordination structures, stabilization energies and spectra properties of actinyl-crown-ether complexes. Our research has shown that the in-cavity complexes and their bonding features between (thio)-crown ethers and f-elements exhibit conventional conformations, with typical An≡Oactinyl and An-Oligand and An-Sligand distances. The typical ionic An-Oligand and An-Sligand bonds with an extent of covalent interaction between the An and ligand donor atoms primarily attributable to the overlap degree of radial distribution of valence atomic orbitals. From U to Cm, LMCT is gradually significant, resulting in the decrease of the formal oxidation state of Am and Cm, and the weakening of the interaction between metal ions and ligands. This periodicity of chemical bonding and the metal oxidation state provide fundamental guidance for the design of reasonable and efficient ligands in the application of lanthanide-actinide separation.
2020, 83(2): 111-120
Abstract:
Natural gas hydrate with abundant resources, high quality and cleanliness, is regarded as a new energy in the 21st century. The study on the hydrate stability and physical characteristics is important for the reservoirs investigation and exploitation. In this paper, the research advances on natural gas hydrate in microscopic scale, mesoscopic scale, macro-scale and mineral scale are described. The calculation results using quantum chemical calculation methods about hydrate structure and stability as well as the characterization of macroscopic physical properties are elaborated. It points out that quantum chemistry is suitable to describe the crystal structure, electron orbital distribution, vibration spectrum, bonding characteristics, host-guest interaction and equilibrium of natural gas hydrate. It will provide theoretical supports for the research of natural gas hydrate in oil and gas storage and transportation, hydrate accumulation as well as production and comprehensive utilization. At present, optimizations of quantum chemical methods, combination of quantum chemical methods with the molecular dynamics simulation and the molecular mechanics simulation will be helpful for the development of investigation of the hydrate formation and dissociation micro mechanism. It can improve the accuracy of the research and enlarge the research system. It will provide basic data for exploitation and utilization of natural gas hydrate in mine scale.
Natural gas hydrate with abundant resources, high quality and cleanliness, is regarded as a new energy in the 21st century. The study on the hydrate stability and physical characteristics is important for the reservoirs investigation and exploitation. In this paper, the research advances on natural gas hydrate in microscopic scale, mesoscopic scale, macro-scale and mineral scale are described. The calculation results using quantum chemical calculation methods about hydrate structure and stability as well as the characterization of macroscopic physical properties are elaborated. It points out that quantum chemistry is suitable to describe the crystal structure, electron orbital distribution, vibration spectrum, bonding characteristics, host-guest interaction and equilibrium of natural gas hydrate. It will provide theoretical supports for the research of natural gas hydrate in oil and gas storage and transportation, hydrate accumulation as well as production and comprehensive utilization. At present, optimizations of quantum chemical methods, combination of quantum chemical methods with the molecular dynamics simulation and the molecular mechanics simulation will be helpful for the development of investigation of the hydrate formation and dissociation micro mechanism. It can improve the accuracy of the research and enlarge the research system. It will provide basic data for exploitation and utilization of natural gas hydrate in mine scale.
2020, 83(2): 121-126
Abstract:
Using ordered mesoporous silica KIT-6 as hard template, cobalt nitrate and cerium nitrate as metal sources, mesoporous CoCeOx composite oxides were prepared by impregnation, filling, calcination, template removal and drying under vacuum-assisted conditions and ordinary stirring conditions. The physical and chemical properties of the composite oxides were characterized by XRD, SEM, TEM and N2 adsorption and desorption techniques. The oxidation performance of toluene was evaluated. The results show that the CoCeOx oxides prepared under vacuum-assisted and stirring conditions are mesoporous Co3O4-CeO2 composite oxides composed of Co3O4 and CeO2. Their specific surface areas are 141 and 89 m2·g-1, respectively. The average pore sizes are 8.7 and 9.6 nm, respectively. The vacuum-assisted nano-replication process is conducive to the full filling of metal salt precursors into the pores of template KIT-6. The prepared mesoporous cobalt-cerium composite oxide has the characteristics of good pore order and large specific surface area, and has certain application prospects in the oxidation removal of volatile organic compounds.
Using ordered mesoporous silica KIT-6 as hard template, cobalt nitrate and cerium nitrate as metal sources, mesoporous CoCeOx composite oxides were prepared by impregnation, filling, calcination, template removal and drying under vacuum-assisted conditions and ordinary stirring conditions. The physical and chemical properties of the composite oxides were characterized by XRD, SEM, TEM and N2 adsorption and desorption techniques. The oxidation performance of toluene was evaluated. The results show that the CoCeOx oxides prepared under vacuum-assisted and stirring conditions are mesoporous Co3O4-CeO2 composite oxides composed of Co3O4 and CeO2. Their specific surface areas are 141 and 89 m2·g-1, respectively. The average pore sizes are 8.7 and 9.6 nm, respectively. The vacuum-assisted nano-replication process is conducive to the full filling of metal salt precursors into the pores of template KIT-6. The prepared mesoporous cobalt-cerium composite oxide has the characteristics of good pore order and large specific surface area, and has certain application prospects in the oxidation removal of volatile organic compounds.
2020, 83(2): 127-131, 155
Abstract:
In this paper, Michael addition reaction was successfully applied to construct nano-fluorescent probe-labeled Salmonella (YB1-INPs). The mild reduction of the disulfide bond (S-S) on the outer membrane protein surface of Salmonella YB1 was achieved by tris(2-carboxyethyl) phosphine, followed by crosslinking with maleimide group (Mal) of indocyanine green (ICG)@nanoprobe (INPs). The morphological and optical properties of YB1-INPs were characterized by scanning electron microscopy (SEM) and confocal fluorescence imaging. The activity of YB1-INPs was investigated by live/dead baclight bacterial viability kit and LB agar plate test. The results showed that nanoprobe INPs were successful labeled on the surface of YB1, while this mild chemical labeling had no adverse effect on the appearance, vitality and growth rate of YB1, and could be used for the fluorescence distribution imaging of Salmonella YB1 in vivo. This simple, safe and efficient fluorescence labeling method provided by this study can label nanomaterials on biological carriers, applying to drug delivery and in vivo monitoring of biological carriers.
In this paper, Michael addition reaction was successfully applied to construct nano-fluorescent probe-labeled Salmonella (YB1-INPs). The mild reduction of the disulfide bond (S-S) on the outer membrane protein surface of Salmonella YB1 was achieved by tris(2-carboxyethyl) phosphine, followed by crosslinking with maleimide group (Mal) of indocyanine green (ICG)@nanoprobe (INPs). The morphological and optical properties of YB1-INPs were characterized by scanning electron microscopy (SEM) and confocal fluorescence imaging. The activity of YB1-INPs was investigated by live/dead baclight bacterial viability kit and LB agar plate test. The results showed that nanoprobe INPs were successful labeled on the surface of YB1, while this mild chemical labeling had no adverse effect on the appearance, vitality and growth rate of YB1, and could be used for the fluorescence distribution imaging of Salmonella YB1 in vivo. This simple, safe and efficient fluorescence labeling method provided by this study can label nanomaterials on biological carriers, applying to drug delivery and in vivo monitoring of biological carriers.
2020, 83(2): 132-138
Abstract:
In this paper, nine verbenone-based thiazole-hydrazone compounds 4a~4i, including three pairs of E-Z isomers and three E-products were synthesized. All the target compounds were characterized by FTIR, 1H NMR, 13C NMR, ESI-MS, and NOESY, and their antifungal activities were evaluated as well. The results showed that, at 50mg/L, compounds 4a~4i showed certain antifungal activities against Physalospora piricola, Gibberella zeae, Fusarium oxysporum f. cucumerinum, Cercospora arachidicola, Alternaria solani, Rhizoctonia solani, Helminthosporium maydis, and Colleetotrichum lagenarium. It was found that the E-Z isomers exhibited obvious difference in antifungal activity against some pathogens. For example, the inhibition rate of (Z)-verbenone-based p-cyanophenyl thiazole-hydrazone (4f) against Gibberella zeae was 6 times that of (E)-verbenone-based p-cyanophenyl thiazole-hydrazone (4e). The frontier molecular orbitals of compounds 4e and 4f were calculated by Gaussian 09 software.
In this paper, nine verbenone-based thiazole-hydrazone compounds 4a~4i, including three pairs of E-Z isomers and three E-products were synthesized. All the target compounds were characterized by FTIR, 1H NMR, 13C NMR, ESI-MS, and NOESY, and their antifungal activities were evaluated as well. The results showed that, at 50mg/L, compounds 4a~4i showed certain antifungal activities against Physalospora piricola, Gibberella zeae, Fusarium oxysporum f. cucumerinum, Cercospora arachidicola, Alternaria solani, Rhizoctonia solani, Helminthosporium maydis, and Colleetotrichum lagenarium. It was found that the E-Z isomers exhibited obvious difference in antifungal activity against some pathogens. For example, the inhibition rate of (Z)-verbenone-based p-cyanophenyl thiazole-hydrazone (4f) against Gibberella zeae was 6 times that of (E)-verbenone-based p-cyanophenyl thiazole-hydrazone (4e). The frontier molecular orbitals of compounds 4e and 4f were calculated by Gaussian 09 software.
2020, 83(2): 139-143
Abstract:
Paeonol can inhibite acetylcholinesterase (AChE) and across the blood-brain barrier (BBB), which lays a solid foundation for the development of new insecticides. In view of this, five paeonol-based phenylsulfonylhydrazone derivatives (5a~5e) were synthesized and evaluated for their in vivo insecticidal activity against a crop-threatening agricultural pest, the pre-third-instar larvae of Mythimna separate, at the concentration of 1mg/mL. Among all the target compounds, compound 5e exhibited significant insecticidal activity, and the final corrected mortality (FMR=50.0%) was equivalent to toosendanin. Meanwhile, some interesting structure-activity relationship results were also discovered:modification of carbonyl on paeonol is acceptable; modification of imino group of intermediate 3 is important for insecticidal activity, and different sulfonated substituents show significant difference in activity. In addition, the insects fed with leaves containing the test compound showed developmental abnormalities during larve, pupae and adult stages.
Paeonol can inhibite acetylcholinesterase (AChE) and across the blood-brain barrier (BBB), which lays a solid foundation for the development of new insecticides. In view of this, five paeonol-based phenylsulfonylhydrazone derivatives (5a~5e) were synthesized and evaluated for their in vivo insecticidal activity against a crop-threatening agricultural pest, the pre-third-instar larvae of Mythimna separate, at the concentration of 1mg/mL. Among all the target compounds, compound 5e exhibited significant insecticidal activity, and the final corrected mortality (FMR=50.0%) was equivalent to toosendanin. Meanwhile, some interesting structure-activity relationship results were also discovered:modification of carbonyl on paeonol is acceptable; modification of imino group of intermediate 3 is important for insecticidal activity, and different sulfonated substituents show significant difference in activity. In addition, the insects fed with leaves containing the test compound showed developmental abnormalities during larve, pupae and adult stages.
2020, 83(2): 144-149
Abstract:
Cervical cancer is a serious threat to women's health due to its high morbidity and high mortality. Traditional treatments are inefficient and the treatment process is extremely painful. In recent years, many natural plant-derived compounds have been identified as promising drug sources for the treatment and prevention of cervical cancer. However, the specific mechanism of natural products for the treatment of cancer has not been clarified. Therefore, eight flavonoid natural small molecule inhibitors were selected and molecularly docked with the high-risk HPV16/18 E6 protein important locus LxxLL hydrophobic pocket to explore the mechanism of natural products against cervical cancer. Docking analysis showed that these natural products interacted strongly with the HPV18E6 protein LxxLL hydrophobic pocket. When docked with HPV16 E6 protein, luteolin binds more deeply than the other seven flavonoids, and these interactions may contribute to the recovery of p53 function. Docking analysis is helpful for understanding the molecular mechanisms of protein-ligand interactions and provides a basis for designing new drugs for the treatment of HPV infection.
Cervical cancer is a serious threat to women's health due to its high morbidity and high mortality. Traditional treatments are inefficient and the treatment process is extremely painful. In recent years, many natural plant-derived compounds have been identified as promising drug sources for the treatment and prevention of cervical cancer. However, the specific mechanism of natural products for the treatment of cancer has not been clarified. Therefore, eight flavonoid natural small molecule inhibitors were selected and molecularly docked with the high-risk HPV16/18 E6 protein important locus LxxLL hydrophobic pocket to explore the mechanism of natural products against cervical cancer. Docking analysis showed that these natural products interacted strongly with the HPV18E6 protein LxxLL hydrophobic pocket. When docked with HPV16 E6 protein, luteolin binds more deeply than the other seven flavonoids, and these interactions may contribute to the recovery of p53 function. Docking analysis is helpful for understanding the molecular mechanisms of protein-ligand interactions and provides a basis for designing new drugs for the treatment of HPV infection.
2020, 83(2): 150-155
Abstract:
In this paper, a new type of ion-supported bis(trifluoroacetoxy)iodobenzene (BTI) reagent was synthesized and used to catalyze the sulfonylation reaction of acetanilide. The effects of oxidant, solvent, additive, temperature and other conditions on the reaction were investigated. After tosyloxylation, the reagent was transformed into ion-supported iodobenzene, which could be recovered, regenerated and recycled three times without losing sulfonylation activity.
In this paper, a new type of ion-supported bis(trifluoroacetoxy)iodobenzene (BTI) reagent was synthesized and used to catalyze the sulfonylation reaction of acetanilide. The effects of oxidant, solvent, additive, temperature and other conditions on the reaction were investigated. After tosyloxylation, the reagent was transformed into ion-supported iodobenzene, which could be recovered, regenerated and recycled three times without losing sulfonylation activity.
2020, 83(2): 156-160
Abstract:
The strong hydrophobicity of polyvinylidene fluoride (PVDF) membrane materials is its main drawback, and hydrophilization modification is the main way to solve this problem. The PVDF/PVA composite membrane was prepared by phase inversion method using PVDF as the base material, polyvinyl alcohol (PVA) as the blending material and N, N-dimethylacetamide (DMAc) as the solvent. The effects of blending ratio of PVDF/PVA, solid content, small molecule additives and polymer additives on the contact angle of the composite film were investigated. The results showed that when the PVDF/PVA blending ratio is 7/3 and the solid content is 13%, the contact angle of the prepared composite membrane is 22.92°; when the additive is anhydrous lithium chloride, nano-silica, and PVP, the contact angle of the composite film is reduced from 53.12°, 30.51° and 41.89° to 0°, respectively. The composite film has the best hydrophilicity when nano-silica is used as an additive. When the additive is glycerin, PMMA, PEG, the contact angle of the composite film increases, and the hydrophilicity deteriorates.
The strong hydrophobicity of polyvinylidene fluoride (PVDF) membrane materials is its main drawback, and hydrophilization modification is the main way to solve this problem. The PVDF/PVA composite membrane was prepared by phase inversion method using PVDF as the base material, polyvinyl alcohol (PVA) as the blending material and N, N-dimethylacetamide (DMAc) as the solvent. The effects of blending ratio of PVDF/PVA, solid content, small molecule additives and polymer additives on the contact angle of the composite film were investigated. The results showed that when the PVDF/PVA blending ratio is 7/3 and the solid content is 13%, the contact angle of the prepared composite membrane is 22.92°; when the additive is anhydrous lithium chloride, nano-silica, and PVP, the contact angle of the composite film is reduced from 53.12°, 30.51° and 41.89° to 0°, respectively. The composite film has the best hydrophilicity when nano-silica is used as an additive. When the additive is glycerin, PMMA, PEG, the contact angle of the composite film increases, and the hydrophilicity deteriorates.
2020, 83(2): 161-166
Abstract:
HPD-750 resin is a medium-polar macroporous adsorption resin with good biocompatibility, stable mechanical properties and large specific surface area, which can be used for immobilizing enzyme. In this paper, pectinase was immobilized by HPD-750 macroporous resin, and the effects of various factors on the immobilized enzyme were studied. The optimized immobilization parameters are:pH 4.0, the immobilization temperature 45℃, the immobilization time 4h, and the amount of enzyme added 0.16g/mL, Under these conditions, the immobilized enzyme activity can reach 5146U/mg. Compared with free pectinase, the immobilized enzyme was found to exhibit better stability of pH and thermo. Additionally, the immobilized pectinase had remarkable reusability and storage stability, the enzyme activity remained more than 80% after 10 cycles of use; and after storage at 4℃ for 25 days, the enzyme activity remained more than 60%. Compared with immobilized enzyme prepared D311 macroporous resin, polyacrylamide and sodium alginate microspheres, the HPD-750 immobilized enzyme has better activity, operational stability, mechanical stability and storage stability. Hence that the HPD-750 macroporous resin could be used as a good carrier material for immobilized enzymes.
HPD-750 resin is a medium-polar macroporous adsorption resin with good biocompatibility, stable mechanical properties and large specific surface area, which can be used for immobilizing enzyme. In this paper, pectinase was immobilized by HPD-750 macroporous resin, and the effects of various factors on the immobilized enzyme were studied. The optimized immobilization parameters are:pH 4.0, the immobilization temperature 45℃, the immobilization time 4h, and the amount of enzyme added 0.16g/mL, Under these conditions, the immobilized enzyme activity can reach 5146U/mg. Compared with free pectinase, the immobilized enzyme was found to exhibit better stability of pH and thermo. Additionally, the immobilized pectinase had remarkable reusability and storage stability, the enzyme activity remained more than 80% after 10 cycles of use; and after storage at 4℃ for 25 days, the enzyme activity remained more than 60%. Compared with immobilized enzyme prepared D311 macroporous resin, polyacrylamide and sodium alginate microspheres, the HPD-750 immobilized enzyme has better activity, operational stability, mechanical stability and storage stability. Hence that the HPD-750 macroporous resin could be used as a good carrier material for immobilized enzymes.
2020, 83(2): 167-171
Abstract:
Uranium is often symbiotic with pyrite in natural uranium ore, and there is an interaction between uranium and pyrite. Organics and microbes in the environment may also have some influence on this symbiosis. In this paper, cyclic voltammetry (CV) was used to study the change of uranium valence state and electron transfer number in pyrite and U(VI) system. The results showed that pyrite could spontaneously reduce U(VI) to U(V) and U(IV). It was also found that humic acid (HA) inhibited the reduction of uranium by pyrite, while thiobacillus ferrooxidans (TF) could promote the reduction process. Photoelectron spectroscopy studies showed that Fe2+ and S- in pyrite both play a role in the reduction of U(VI). The mechanism of reduction and enrichment of uranium in pyrite is studied from the microscopic perspectives of electron and ion, and the symbiosis of uranium and pyrite in natural uranium ore is explained, which provides a new basis for the theory of uranium mineralization. It provides a new theoretical basis for the application of pyrite in environmental pollution restoration and the degree of influence of the surrounding environment.
Uranium is often symbiotic with pyrite in natural uranium ore, and there is an interaction between uranium and pyrite. Organics and microbes in the environment may also have some influence on this symbiosis. In this paper, cyclic voltammetry (CV) was used to study the change of uranium valence state and electron transfer number in pyrite and U(VI) system. The results showed that pyrite could spontaneously reduce U(VI) to U(V) and U(IV). It was also found that humic acid (HA) inhibited the reduction of uranium by pyrite, while thiobacillus ferrooxidans (TF) could promote the reduction process. Photoelectron spectroscopy studies showed that Fe2+ and S- in pyrite both play a role in the reduction of U(VI). The mechanism of reduction and enrichment of uranium in pyrite is studied from the microscopic perspectives of electron and ion, and the symbiosis of uranium and pyrite in natural uranium ore is explained, which provides a new basis for the theory of uranium mineralization. It provides a new theoretical basis for the application of pyrite in environmental pollution restoration and the degree of influence of the surrounding environment.
2020, 83(2): 172-178
Abstract:
In this paper, iron based bimetallic materials (Cu/Fe and Pd/Fe) were prepared and their reductive dehalogenation effects on bromoform was investigated. The reduction effect of Cu/Fe and Pd/Fe bimetal materials on bromoform will increase as the addition amount of bimetal increases; the presence of high concentration of H+ in the solution is conducive to the reduction; furthermore, the presence of dissolved oxygen has a inhibitory effect on reductive dehalogenation. The reductive dehalogenation between bimetallic materials and bromoform includes direct reduction and indirect reduction. Bimetallic materials achieved high performance because galvanic cells were created between Fe (serving as an anode) and plating elements (serving as a cathode). This structure enhanced the reducibility of iron for reductive dehalogenation by facilitating iron corrosion. The Pd/Fe system showed a better performance than Cu/Fe, which was attributed to a higher potential gradient that promoting the hydrogen production.
In this paper, iron based bimetallic materials (Cu/Fe and Pd/Fe) were prepared and their reductive dehalogenation effects on bromoform was investigated. The reduction effect of Cu/Fe and Pd/Fe bimetal materials on bromoform will increase as the addition amount of bimetal increases; the presence of high concentration of H+ in the solution is conducive to the reduction; furthermore, the presence of dissolved oxygen has a inhibitory effect on reductive dehalogenation. The reductive dehalogenation between bimetallic materials and bromoform includes direct reduction and indirect reduction. Bimetallic materials achieved high performance because galvanic cells were created between Fe (serving as an anode) and plating elements (serving as a cathode). This structure enhanced the reducibility of iron for reductive dehalogenation by facilitating iron corrosion. The Pd/Fe system showed a better performance than Cu/Fe, which was attributed to a higher potential gradient that promoting the hydrogen production.
2020, 83(2): 179-182
Abstract:
Carbon nanotubes (CNTs) were dispersed in polycarbonate (PC) matrix by solution method. Then the obtained PC/CNT flocculation was used to prepare the flexible thermoelectric PC/CNT composites by compression molding. The fractured morphology of PC/CNT composite suggested that CNTs are distributed homogenously in the PC matrix. Besides, with increasing CNT contents, the electrical conductivities increase dramatically whereas the Seebeck coefficients nearly remain constant. This leads to the rapid increasing trend of power factor with CNT content for the PC/CNT composites. The maximum power factor is 4.6 μW·m-1·K-2.
Carbon nanotubes (CNTs) were dispersed in polycarbonate (PC) matrix by solution method. Then the obtained PC/CNT flocculation was used to prepare the flexible thermoelectric PC/CNT composites by compression molding. The fractured morphology of PC/CNT composite suggested that CNTs are distributed homogenously in the PC matrix. Besides, with increasing CNT contents, the electrical conductivities increase dramatically whereas the Seebeck coefficients nearly remain constant. This leads to the rapid increasing trend of power factor with CNT content for the PC/CNT composites. The maximum power factor is 4.6 μW·m-1·K-2.
2020, 83(2): 183-185
Abstract:
This study disclosed a new method for the synthesis of resveratrol. The key intermediate N'-(3, 5-dimethoxyphenyl)acetohydrazide (4) was obtained by using 3, 5-dimethoxyaniline as the starting material via diazotization, reduction and acetylation, which was condensed with 4-methoxystyrene to give the intermediate 5 via Mizoroki-Heck coupling reaction. The titled compound resveratrol (1) was prepared by final demethylation of 5 with a total yield of 31.9%. The structure of the intermediates and target product were confirmed by mass spectrum (MS) and 1H NMR. This procedure is characterized by handy operations and mild conditions, and can be used for the scale-up preparation of resveratrol.
This study disclosed a new method for the synthesis of resveratrol. The key intermediate N'-(3, 5-dimethoxyphenyl)acetohydrazide (4) was obtained by using 3, 5-dimethoxyaniline as the starting material via diazotization, reduction and acetylation, which was condensed with 4-methoxystyrene to give the intermediate 5 via Mizoroki-Heck coupling reaction. The titled compound resveratrol (1) was prepared by final demethylation of 5 with a total yield of 31.9%. The structure of the intermediates and target product were confirmed by mass spectrum (MS) and 1H NMR. This procedure is characterized by handy operations and mild conditions, and can be used for the scale-up preparation of resveratrol.
2020, 83(2): 186-191
Abstract:
The personal experience of German female chemist Ida Noddack has important reference function and value for understanding female scientists of her time. Before and after the second world war, Germany banned paid jobs for married women, including female scientists. In this context, Ida Noddack and her husband Walter Noddack worked together for a long time in the years before the marriage, including the 30 years after the marriage, to win the opportunity and the environment for scientific research. After her marriage, Ida Noddack was almost always 'unpaid' and even had no clear research position, which led to unnecessary discrimination. Nevertheless, Ida Noddack made important scientific achievements, especially in the discovery of rhenium and the prediction of nuclear fission. Ida Noddack has received some honors and recognition, but we still need to deepen our understanding of her.
The personal experience of German female chemist Ida Noddack has important reference function and value for understanding female scientists of her time. Before and after the second world war, Germany banned paid jobs for married women, including female scientists. In this context, Ida Noddack and her husband Walter Noddack worked together for a long time in the years before the marriage, including the 30 years after the marriage, to win the opportunity and the environment for scientific research. After her marriage, Ida Noddack was almost always 'unpaid' and even had no clear research position, which led to unnecessary discrimination. Nevertheless, Ida Noddack made important scientific achievements, especially in the discovery of rhenium and the prediction of nuclear fission. Ida Noddack has received some honors and recognition, but we still need to deepen our understanding of her.
