Study of Ruthenium compounds for the photooxidation of alcohols in water

Abstract

In this dissertation work an optimized synthetic route has been developed to obtain different ruthenium complexes with N-donor ligand types. Afterwards, the efficiency of an aqua complex as a catalyst for the photo oxidation of alcohols has been evaluated. Initially, one of the non-commercial N-donor ligands (pypz-pyrene) L3 and then the starting product [RuCl3(trpy)] C1 have been synthetized. This last one reacts with the ligand L3 to generate a mixture of chloro compounds cis and trans-[RuCl(trpy)(pypz-pyrene)](PF6) C2b and C2a. These isomers have been separated by a chromatographic column. Later, starting from the chloro complex C2a the aqua-complex trans-[Ru(trpy)(pypz-pyrene)(OH2)](PF6)2 C3a has been synthetized. All the compounds have been characterized in solution through spectroscopic techniques (RMN, UV-Visible, ESI-MS) and some of them by X-ray diffraction. The redox properties of the compounds have been studied by CV and DPV. It was possible to funcionalize graphite electrodes for the complexes C2a and C3a by an electro polimerization process thanks to the presence of the pyrene group. The Pourbaix diagram presented for the compound trans-[Ru(trpy)(pypz-pyrene)(OH2)](PF6)2 C3a has allowed to obtain information of the redox equilibrium as well as extract the correspondent pKa values of the RuII i RuIII. Finally, the catalytic activity of the complex trans-[Ru(trpy)(pypz-pyrene)(OH2)](PF6)2 C3a has been evaluated by the photo oxidation of 1-phenil ethanol in water and it has been observed a moderate conversion with an excellent selectivity value