Search

A novel heterogeneous catalyst, alkaloid@Cu was prepared by the entrapment of commercially purchased alkaloids within non-noble metallic copper nanoparticles. This composite was compacted into a coin and directly used as cathode for electrocatalytic asymmetric hydrogenation of aromatic ketones. Using water as hydrogen source, optically active alcohols with 71% ee value and 93% yield were obtained under very mild conditions. Keywords: Copper nanoparticles, Encapsulated alkaloids, Electrocatalytic hydrogenation, Asymmetric hydrogenation

Copper nanoparticles were prepared in an aqueous solution, compacted into a coin, and used as a cathode for asymmetric hydrogenation by the electrochemical method for the first time. A good ee value and excellent yield were obtained under mild conditions. Electrochemical conditions were crucial for alkaloid adsorption on metallic Cu, which is a key process of asymmetric induction. Furthermore, the ee value was linear with an adsorption amount. Keywords: Copper nanoparticles, Asymmetric hydrogenation, Electrochemical conditions, Alkaloids, Adsorption

In this paper, the one-step synthesis of enantiomerically pure cyclic carbonates has been developed by electrolyzing the chiral epoxides and CO2 (0.1 MPa, rt) in an undivided cell with a 316 stainless steel (SS) cathode and a Mg sacrificial anode containing TEAI–MeCN as supporting electrolyte and solvent with a constant current. To deeply understand this reaction, the effects of various synthesis conditions were investigated using R-styrene oxide as the model compound. Under the optimized conditions, the maximum conversion is 67% with 96% selectivity and 98.8% ee value for R-styrene carbonate. Finally, the reaction mechanism has been proposed by comparative electrolysis and DFT calculation. Keywords: Electrosynthesis, Cyclic carbonates, CO2, Chiral epoxides

The feasibility of asymmetric electrocarboxylation of 1-phenylethyl chloride catalyzed by the electrogenerated chiral [CoI(salen)]− complex has been investigated for the first time. Using this system, optically active 2-phenylpropionic acid in 37% yield and 83% ee is synthesized from 1-phenylethyl chloride and CO2. The electrochemical behavior of the catalyst and the optimization of synthesis conditions are discussed. This study provides a new procedure for the asymmetric synthesis of a chiral compound and expands the applications of chiral CoII(salen) in the electrochemical asymmetric fixation of CO2. Keywords: Asymmetry, Electrocarboxylation, 1-Phenylethyl chloride, CO2, chiral CoII(salen) complex

Hierarchically structured europium-doped zinc oxide (Eu-ZnO) nanocrystalline aggregates were synthesized through solvothermal method. The dye-sensitized solar cell (DSC) fabricated using the Eu-ZnO aggregates as photoanode exhibits effective electron injection and enhanced electron transport properties, which greatly improve Jsc (12.0 to 15.5 mA cm−2) and η (4.5 to 5.7%), compared with those corresponding values of undoped ZnO aggregates based DSC. Furthermore, the Eu-ZnO DSC showed low efficiency decay with no more than 6% loss in 30 days, demonstrating an effective way to increase the cell efficiency by the doping of hierarchical ZnO nanocrystalline aggregates as well as a great potential for practical application. Keywords: Dye-sensitized solar cell, Eu-doped ZnO aggregates, STEM, Electron injection, Electron transport

We report the fabrication of polydisperse ZnO aggregates and subsequent optimization as effective photoelectrodes for dye-sensitized solar cells (DSCs) by controlling the annealing procedures. Two dyes, a metal-free indoline D149 and a commercial ruthenium complex N719 were used as sensitizers of ZnO DSCs with the maximum efficiencies (η) of 5.2% and 4.5%, respectively. The monolithic D149-based and N719-based ZnO DSCs with respective active area of 2.4 cm2 were also technically explored for the first time, reaching up to the η of 2.6% and 2.4%, respectively. The higher η of D149-based DSCs than N719-based DSCs is ascribed to expanded light harvesting and reduced interface resistance. Therefore, D149 can be considered as a better sensitizer candidate for application in low-cost ZnO based DSCs. Keywords: Dye-sensitized solar cells, ZnO aggregates, Monolithic, D149, N719

The voltammetry of adhered microparticles provides a convenient method to access “water free” reversible potentials for water sensitive reduction of benzophenone and 1,4-benzoquinone in “wet” 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Bmpyrd][NTf2]) (water content~0.13 M) ionic liquid. The outcome that reflects reversible potentials relevant to “dry” conditions is rationalized in terms of generation of high localized concentrations that significantly exceed the water concentration near the electrode surface. Keywords: Voltammetry of adhered microparticles, Ionic liquids, Benzophenone, 1,4-benzoquinone, Water

A simple and eco-friendly electrochemical route was developed by using silver as the cathode, magnesium as the anode and ionic liquid BMIMBF4 as solvent for the electrochemical dimerisation of aromatic bromides. The electrochemical behaviour was studied at different electrodes (Ag, Cu, Ni and Ti) by cyclic voltammetry, which shows significant electrocatalytic effect of the silver electrode towards the reductive dimerisation of aromatic bromides. Biaryls were obtained in moderate to good yield (12–68%). A recycling study confirmed that the solvent can be reused multiple times without activity loss. Keywords: Ionic liquid, Electrocatalytic dimerisation, Silver electrode, Aromatic bromides

The feasibility of electrocarboxylation of activated olefins has been investigated in CO2-saturated room-temperature ionic liquid BMIMBF4 solution for the first time. The electrochemical behavior has been studied on GC electrode by cyclic voltammetry, showing a diffusion controlled irreversible reduction process. The synthesis has been carried out under mild (PCO2 = 1 atm, t = 50 °C) and safe conditions in undivided cell, and the use of volatile and toxic solvents and catalysts, as well as of any supporting electrolyte, was avoided. Monocarboxylic acids were obtained in moderate yield (35–55%). Furthermore, the ionic liquid has been recycled for five times, which did not affect the product yield greatly. Keywords: Ionic liquid, Carbon dioxide, Electrocarboxylation, Activated olefin

Here we describe the utilization of NHC–CO2 which transfers CO2 to alcohols for the synthesis of dialkyl carbonates under mild conditions with high conversion and excellent selectivity. In addition NHC–CO2 formation was supported by electrochemical analysis. This study provides a new procedure for the synthesis of dialkyl carbonates of chemical and pharmaceutical interest, as well as expands the applications of NHCs in CO2 fixation. Keywords: N-heterocyclic carbenes, Electrosynthesis, CO2, Dialkyl carbonates, Ionic liquid