MODIFICATION OF TRANSITION METAL CATIONS TO POLYMER-STABILIZED PLATINUM COLLOIDAL CLUSTERS IN ENANTIOSELECTIVE HYDROGENATION OF METHYL PYRUVATE

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.

Study of the Complexation Behavior of Calixarene with Transition Metal Cations by UV-vis and Fluorescent Spectra

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.

New Approach to Synthesis of Silica with Chemically Bound Guanidine Hydrochloride for Preconcentration of Metal Ions

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.

Rare earth and transitional metal colloidal supercapacitors

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.

Theoretical Study on the Dehydrogenation Reaction of H_2S by VS^+ (~3Σ^-)

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.