Synthesis Of Mononuclear Ruthenium Complexes Modified By Anionic Ligand And Study On Catalytic Water Oxidation

The development of viable molecular water oxidation catalysts remains an issue of central importance for reserving solar fuel. For purpose of gaining insight into the ligand structure-catalytic activity relationship and optimizing the catalysts’ performance, three novel mononuclear Ru(II) complexes with anionic tridentate ligand(C1 = [RuII(L1)(pic)3]Cl, C2 = [RuII(L1)(bpy)(pic)]Cl, C3 = [RuII(L1)2) have been prepared and characterized by 1H NMR, 13 C NMR and ESI-MS spectroscopies and they showed sufficient solubility in aqueous solution. The effect of the ligand structures on electronic and catalytic activities is investigated. In the presence of a large excess of(NH4)2Ce(NO3)6(CAN) under acidic conditions, complexes 1 and 2 are able to catalyze water oxidation wherein complex 1 displays better catalytic performance with a turnover of 970. In addition, it successfully achieves photochemical water oxidation in a three component system. Conversely, complex 3 fails to catalyze water oxidation both in chemical and photochemical conditions. For the viewpoint of reactivity, the influence of ligand geometry is noticeable, presumably due to the different rate of N-donor ligand/H2 O exchange among three complexes, and a RuIII-H2 O complex is the real catalyst..The superiority of our catalyst is following:(i) The negatively charged ligand can increase the electron density of the ruthenium center and thus lower the oxidation potential, which makes it possible to match the oxidation potential of the catalyst with that of commonly used photosensitizers(ii) the introduction of rigid phenanthroline ligands results in better stabilize,it was not lose the catalytic activities though ten hours. no RuO2 nanoparticle in situ formed(iii) the catalyst showed sufficient solubility in aqueous solution.that’s can better insight into O2 evolution mechanism.Other synthesized one ligand L2 and one ruthenium complexes C4, L2 have been characterized by 1H NMR, and ESI-MS spectroscopies and C4 have been characterized by ESI-MS and it also showed sufficient solubility in aqueous solution.it also have catalytic activity by water oxidation catalysts.because of the Ru is a novel metal, now more an more people like insight into no novel metal complexes.so no novel metal comlexes with L2 will have great significance.