Chiral ammonium-capped rhodium(0) nanocatalysts: synthesis, characterization, and advances in asymmetric hydrogenation in neat water.

Optically active amphiphilic compounds derived from N-methylephedrine, N-methylprolinol, or cinchona derivatives possessing bromide or chiral lactate counterions were efficiently used as protective agents for rhodium(0) nanoparticles. The full characterization of these surfactants and the obtained nanocatalysts was performed by means of different techniques. These spherical nanoparticles, with sizes between 0.

New ammonium surfactant-stabilized rhodium(0) colloidal suspensions: influence of novel counter-anions on physico-chemical and catalytic properties.

Novel anionic species, such as hydrogen carbonate (HCO(3)(−)), fluoride (F(−)), triflate (CF(3)SO(3)(−)), tetrafluoroborate (BF(4)(−)) and chloride (Cl(−)) were investigated as new partners of water soluble N,N-dimethyl-N-cetyl-N-(2-hydroxyethyl) ammonium salts, used as a protective agent of rhodium colloids. The effect of the surfactant polar head on the micellar behavior, size and morphology of the nanospecies was studied by adapted physico-chemical experiments (surface tension measurements, dynamic light scattering, thermogravimetric and TEM analyses) and discussed in terms of strong or weak stabilization of the growing nanoparticles surface. Finally, the influence of the nanoenvironment generated by the surfactant with various counter-anions was evaluated via the hydrogenation of aromatics.