Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate.Compared to the enantiomeric excess(e.e....Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate.Compared to the enantiomeric excess(e.e.)value(71.4%) obtained without the presence of metal cations,obvious e.e.enhancement(up to 82.5%)was resulted from the addition of Zn^(2+) but with a certain decrease in activity.The reaction parameters in the presence of Zn^(2+) were also studied.It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.展开更多
Guanidine hydrochloride was chemically bonded to surface of modified silica by means of condensation with grafted amino groups. Ion-exchanging and complexing properties of the obtained adsorbent have been studied with...Guanidine hydrochloride was chemically bonded to surface of modified silica by means of condensation with grafted amino groups. Ion-exchanging and complexing properties of the obtained adsorbent have been studied with respect to cations of Zn(II), Cu(II), Pb(II), Cd(II), Co(II) and metal-containing oxoanions of W(VI), Mo(VI), Cr(VI), V(V). Optimum conditions for quantitative extraction of the studied ions were determined. The structure and composition of Co(II) and Cu(II) complexes on the surface of the synthesized adsorbent have been investigated. The possibility of quantitative determination of cobalt(II) and copper(II) trace amounts after their preconcentration by the synthesized adsorbent was demonstrated.展开更多
The dehydrogenation reaction of H2S by the ^3Σ^- ground state of VS^＋： VS^＋ ＋ H2S → VS2^＋ ＋ H2 has been studied by using Density Functional Theory （DPT） at the B3LYP/DZVP level. It is found that the reaction...The dehydrogenation reaction of H2S by the ^3Σ^- ground state of VS^＋： VS^＋ ＋ H2S → VS2^＋ ＋ H2 has been studied by using Density Functional Theory （DPT） at the B3LYP/DZVP level. It is found that the reaction proceeds along two possible pathways （A and B） yielding two isomer dehydrogenation products VS2^＋-1 （^3B2） and VS2^＋-2 （^3A1）, respectively. For both pathways, the reaction has a two-step-reaction mechanism that involves the migration of two hydrogen atoms from S2 to V^＋, respectively. The migration of the second hydrogen via TS3 and that of the first via TS4 are the rate-determining steps for pathways A and B, respectively. The activation energy is 17.4 kcal/mol for pathway A and 22.8 kcal/mol for pathway B relative to the reactants. The calculated reaction heat of 9.9 kcal/mol indicates the endothermicity of pathway A and that of -11.9 kcal/mol suggests the exothermicity of pathway B.展开更多
A new fluorescent compound based on calixarene skeleton was synthesized. Its complexation ability with transition metal ions, such as Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ and Ag +, was investig...A new fluorescent compound based on calixarene skeleton was synthesized. Its complexation ability with transition metal ions, such as Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ and Ag +, was investigated by UV vis and fluorescent spectra.展开更多
The geometries and bonding characteristics of the first-row transition-metal carbene cations MCH<sub>2</sub><sup>+</sup> were investigated by ab initio molecular orbital theory （HF/LANL2DZ）. ...The geometries and bonding characteristics of the first-row transition-metal carbene cations MCH<sub>2</sub><sup>+</sup> were investigated by ab initio molecular orbital theory （HF/LANL2DZ）. All of MCH<sub>2</sub><sup>+</sup> are coplanar. In the closed shell structures the C bonds to M with double bonds; while in the open shell structures the partial double bonds are formed, because one of the σ and π orbitals is singly occupied. It is mainly the π-type overlap between the 2p<sub>x</sub> orbital of C and 4p<sub>x</sub>, 3d<sub>xz</sub>, orbitals of M<sup>+</sup> that forms the π orbitals. The dissociation energies of C—M bond appear in periodic trend from Sc to Cu. Most of the calculated bond dissociation energies are close to the experimental ones.展开更多
采用离子色谱抑制电导检测若干过渡金属离子.由于淋洗液抑制后成中性,过渡金属离子易发生水解形成氢氧化物沉淀而无法采用抑制电导检测,实验中采用在常规强酸淋洗液中加入两性离子,用于控制抑制后淋洗液的pH值.经过实验,在Waters IC-Pak...采用离子色谱抑制电导检测若干过渡金属离子.由于淋洗液抑制后成中性,过渡金属离子易发生水解形成氢氧化物沉淀而无法采用抑制电导检测,实验中采用在常规强酸淋洗液中加入两性离子,用于控制抑制后淋洗液的pH值.经过实验,在Waters IC-Pak C M/D柱上(150mm×3.9mm,ID)确定淋洗液条件为6.5mmol·L-1甲基磺酸(MSA)和10mmol·L-14-羟基乙基哌嗪乙磺酸(HEPES),Co2+、Ni2+、Zn2+和Cu2+等4种过渡金属离子在抑制电导检测下得到了检测信号并与碱金属、铵离子和碱土金属离子获得了较好的分离.在该实验条件下,方法具有较好的灵敏度(检测下限1.31～31.2μg·L-1)和重现性(时间RSD小于0.86%,峰面积RSD小于5.09%).展开更多
The search of electrode materials with high electrochemical activity is one of key solutions to actualize both high energy density and high power density in a supercapacitor. Recently, we have developed one novel kind...The search of electrode materials with high electrochemical activity is one of key solutions to actualize both high energy density and high power density in a supercapacitor. Recently, we have developed one novel kind of rare earth and transitional metal colloidal supercapacitors, which can deliver higher specific capacitance than electrical double-layer capacitors(EDLC) and traditional pseudocapacitors. The electrode materials in colloidal supercapacitors are in-situ formed electroactive colloids, which were transformed from commercial rare earth and transitional metal salts in alkaline electrolyte by chemical and electrochemical assisted coprecipitation. In these colloidal supercapacitors, multiple-electron Faradaic redox reactions can be utilized, which can deliver ultrahigh specific capacitance often larger than one-electron capacitance. Multiple-valence metal cations used in our designed colloidal supercapacitors mainly include Ce3+, Yb3+, Er3+, Fe3+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Sn2+ and Sn4+. The colloidal supercapacitors can be served as the promising next-generation high performance supercapacitors.展开更多
Interaction between amphotericin B（AmB） and cell membrane is influenced by different metal cations. In the presence of K＋, Na＋ or Ca2＋ ions, the surface pressure-area isotherms and the elastic modulus of an ampho...Interaction between amphotericin B（AmB） and cell membrane is influenced by different metal cations. In the presence of K＋, Na＋ or Ca2＋ ions, the surface pressure-area isotherms and the elastic modulus of an amphotericindipalmitoylphosphatidylcholine（AmB-DPPC） mixed monolayer were discussed. And the excess free energy and entropies of mixing were calculated according to the surface pressure-area isotherms. The phase transition of the mixed monolayer needed a higher concentration of AmB in the sequence Na ＋〉pure buffer〉K＋〉Ca2＋. When the molar fraction of AmB（XAmB） was 0.5, the molecular interaction changed from attraction to repulsion and the mixed monolayer turned to ordered state from disorder state under the induction of K＋ or Ca2＋ ions at all surface pressure in our experiment. At high surface pressure, the disorder of monolayer enhanced in the presence of Na＋ ions at XAmB〉0.1. At different molar ratios of AraB, the influences of these metal cations were discrepant. These cations may influence Arab molecules to form pores on the monolayer. It is helpful to understand the reduction of AmB＇s toxicity as theoretical reference.展开更多
基金The project is partially supported by the Natural Science Foundation of Hubei Province Contract(No.2003ABA072)
文摘Modification of transition metal cations to polymer-stabilized Pt colloidal clusters modified with cinchonidine was studied in enantioselective hydrogenation of methyl pyruvate.Compared to the enantiomeric excess(e.e.)value(71.4%) obtained without the presence of metal cations,obvious e.e.enhancement(up to 82.5%)was resulted from the addition of Zn^(2+) but with a certain decrease in activity.The reaction parameters in the presence of Zn^(2+) were also studied.It was found that the Pt colloidal catalysts in the presence of metal cations performed very differently from that in the absence of metal cations.
文摘Guanidine hydrochloride was chemically bonded to surface of modified silica by means of condensation with grafted amino groups. Ion-exchanging and complexing properties of the obtained adsorbent have been studied with respect to cations of Zn(II), Cu(II), Pb(II), Cd(II), Co(II) and metal-containing oxoanions of W(VI), Mo(VI), Cr(VI), V(V). Optimum conditions for quantitative extraction of the studied ions were determined. The structure and composition of Co(II) and Cu(II) complexes on the surface of the synthesized adsorbent have been investigated. The possibility of quantitative determination of cobalt(II) and copper(II) trace amounts after their preconcentration by the synthesized adsorbent was demonstrated.
文摘The dehydrogenation reaction of H2S by the ^3Σ^- ground state of VS^＋： VS^＋ ＋ H2S → VS2^＋ ＋ H2 has been studied by using Density Functional Theory （DPT） at the B3LYP/DZVP level. It is found that the reaction proceeds along two possible pathways （A and B） yielding two isomer dehydrogenation products VS2^＋-1 （^3B2） and VS2^＋-2 （^3A1）, respectively. For both pathways, the reaction has a two-step-reaction mechanism that involves the migration of two hydrogen atoms from S2 to V^＋, respectively. The migration of the second hydrogen via TS3 and that of the first via TS4 are the rate-determining steps for pathways A and B, respectively. The activation energy is 17.4 kcal/mol for pathway A and 22.8 kcal/mol for pathway B relative to the reactants. The calculated reaction heat of 9.9 kcal/mol indicates the endothermicity of pathway A and that of -11.9 kcal/mol suggests the exothermicity of pathway B.
文摘A new fluorescent compound based on calixarene skeleton was synthesized. Its complexation ability with transition metal ions, such as Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ and Ag +, was investigated by UV vis and fluorescent spectra.
基金Project supported by the National Natural Science Foundation of China (Grant No. 29170070)
文摘The geometries and bonding characteristics of the first-row transition-metal carbene cations MCH<sub>2</sub><sup>+</sup> were investigated by ab initio molecular orbital theory （HF/LANL2DZ）. All of MCH<sub>2</sub><sup>+</sup> are coplanar. In the closed shell structures the C bonds to M with double bonds; while in the open shell structures the partial double bonds are formed, because one of the σ and π orbitals is singly occupied. It is mainly the π-type overlap between the 2p<sub>x</sub> orbital of C and 4p<sub>x</sub>, 3d<sub>xz</sub>, orbitals of M<sup>+</sup> that forms the π orbitals. The dissociation energies of C—M bond appear in periodic trend from Sc to Cu. Most of the calculated bond dissociation energies are close to the experimental ones.
文摘采用离子色谱抑制电导检测若干过渡金属离子.由于淋洗液抑制后成中性,过渡金属离子易发生水解形成氢氧化物沉淀而无法采用抑制电导检测,实验中采用在常规强酸淋洗液中加入两性离子,用于控制抑制后淋洗液的pH值.经过实验,在Waters IC-Pak C M/D柱上(150mm×3.9mm,ID)确定淋洗液条件为6.5mmol·L-1甲基磺酸(MSA)和10mmol·L-14-羟基乙基哌嗪乙磺酸(HEPES),Co2+、Ni2+、Zn2+和Cu2+等4种过渡金属离子在抑制电导检测下得到了检测信号并与碱金属、铵离子和碱土金属离子获得了较好的分离.在该实验条件下,方法具有较好的灵敏度(检测下限1.31～31.2μg·L-1)和重现性(时间RSD小于0.86%,峰面积RSD小于5.09%).
基金supported by the National Natural Science Foundation of China(Grant Nos.51125009&91434118)the National Natural Science Foundation for Creative Research Group(Grant No.21221061)+1 种基金the External Cooperation Program of BIC,Chinese Academy of Sciences(Grant No.121522KYS820150009)the Hundred Talents Program of the Chinese Academy of Sciences
文摘The search of electrode materials with high electrochemical activity is one of key solutions to actualize both high energy density and high power density in a supercapacitor. Recently, we have developed one novel kind of rare earth and transitional metal colloidal supercapacitors, which can deliver higher specific capacitance than electrical double-layer capacitors(EDLC) and traditional pseudocapacitors. The electrode materials in colloidal supercapacitors are in-situ formed electroactive colloids, which were transformed from commercial rare earth and transitional metal salts in alkaline electrolyte by chemical and electrochemical assisted coprecipitation. In these colloidal supercapacitors, multiple-electron Faradaic redox reactions can be utilized, which can deliver ultrahigh specific capacitance often larger than one-electron capacitance. Multiple-valence metal cations used in our designed colloidal supercapacitors mainly include Ce3+, Yb3+, Er3+, Fe3+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Sn2+ and Sn4+. The colloidal supercapacitors can be served as the promising next-generation high performance supercapacitors.
文摘Interaction between amphotericin B（AmB） and cell membrane is influenced by different metal cations. In the presence of K＋, Na＋ or Ca2＋ ions, the surface pressure-area isotherms and the elastic modulus of an amphotericindipalmitoylphosphatidylcholine（AmB-DPPC） mixed monolayer were discussed. And the excess free energy and entropies of mixing were calculated according to the surface pressure-area isotherms. The phase transition of the mixed monolayer needed a higher concentration of AmB in the sequence Na ＋〉pure buffer〉K＋〉Ca2＋. When the molar fraction of AmB（XAmB） was 0.5, the molecular interaction changed from attraction to repulsion and the mixed monolayer turned to ordered state from disorder state under the induction of K＋ or Ca2＋ ions at all surface pressure in our experiment. At high surface pressure, the disorder of monolayer enhanced in the presence of Na＋ ions at XAmB〉0.1. At different molar ratios of AraB, the influences of these metal cations were discrepant. These cations may influence Arab molecules to form pores on the monolayer. It is helpful to understand the reduction of AmB＇s toxicity as theoretical reference.
