The effect of various proton-donors on the electrochemical reduction of 1,4-benzoquinone (BQ) was investigated in acetonitrile, dimethylsulfoxide and methylene chloride. Three representative types of acids, protonated amines, carboxylic acids and phenol derivatives, were used as proton-donors to cover a wide range of pKa. As a proton-donor is added, a new peak appears and the magnitude of the p...

Redox-active organic dendrimers are of interest for a variety applications, e. g. as components in optoelectronic devices and energy-storage (battery) materials, were also used to model enzymatic reactivity. Here, we report the first synthesis redox-active dendrimer-like oligoguanidines, assembling six or twelve guanidino groups attached aromatic cores one molecule. The novel being strong elect...

We show that reduced rhenium bipyridyl carbonyl complexes are stable and selective catalysts for deoxygenation of nitrous oxide (N2O) in organic media the presence water. Mechanistic studies indicate Re complex is initially to produce activated species. N2O then binds labile position at metal resulting adduct further trigger N–O bond breaking release N2. Proton donors beneficial enhance catalyt...

The reduction of 1,1-diaryl-2,2-dicyanoethylenes with SmI(2) in THF was studied in the presence of four proton donors: H(2)O, MeOH, i-PrOH and trifluoroethanol (TFE). The kinetic order for the first two is nearly unity at low proton donor concentrations and approaches four at high concentrations, whereas, for i-PrOH and TFE, the log-log plot is linear with a slope smaller than one. Detailed ana...

The maximal velocity of catalysis of CO(2) hydration by human carbonic anhydrase II (HCA II) requires proton transfer from zinc-bound water to solution assisted by His 64. The catalytic activity of a site-specific mutant of HCA II in which His 64 is replaced with Ala (H64A HCA II) can be rescued by exogenous proton donors/acceptors, usually derivatives of imidazole and pyridine. X-ray crystallo...

In 1678, Stefano Lorenzini first described a network of organs of unknown function in the torpedo ray-the ampullae of Lorenzini (AoL). An individual ampulla consists of a pore on the skin that is open to the environment, a canal containing a jelly and leading to an alveolus with a series of electrosensing cells. The role of the AoL remained a mystery for almost 300 years until research demonstr...

Palladium(II) in combination with a monodentate phosphine ligand enables the unprecedented direct and α-stereoselective catalytic synthesis of deoxyglycosides from glycals. Initial mechanistic studies suggest that in the presence of N-phenyl-2-(di-tert-butylphosphino)pyrrole as the ligand, the reaction proceeds via an alkoxy palladium intermediate that increases the proton acidity and oxygen nu...