Ruthenium Metal Complexes And CoP / CdS Mixture For Photocatalytic Oxidation Of Organic Substrates

The efficient harnessing of solar energy for power applications provides a novel and promising approach for resolving the environmental and energy problems of human society. In this thesis, we have prepared two novel Ruthenium complexes as water oxidation catalysts based on the classic Ru(bpy)(tpy)X complex, the modified tri-nuclear complexes were linked by a conjugated ligand motif which exerted certain steric and electronic effects on the catalysts and therfore resulted in substantially improved catalytic activities.1. A three nuclear symmetric ruthenium catalyst(T1) connected by a conjugated benzene structure was prepared with2,4,6-Trimethylbenzene-1,3,5-tricarbaldehyde as starting material, further substitution of the Cl ligand with H2 O resulted in the formation of complex 2(T2).The complexes were successfully characterized by a series of techniques like1 HNMR and ESI. The photophysical properties were evaluated by UV-vis evolution and electrochemical experiments, which have provided some mechanistic insight into the water oxidation process. The metal complexes T1 and T2 were subsequently tested for chemical water oxidation reaction. In comparison with mononuclear Ru(bpy)(tpy)H2O Complex, we came to find that the linked three nuclear complex T2 exhibited more than two-fold higher catalytic activity under the same molar amount of Ru metal center at reaction time of 5000 s. This also confirmed that the strategy of introducing conjugation ligand motif had the effect of reducing the redoxpotential of the metal complex which improved the catalytic activity. This realization would also be beneficial for the subsequent development of more efficient water oxidation complexes. Furthermore, we also conducted the visible light driven alcohol oxidation experiments by using T1 as catalyst and 6 different kinds of benzyl alcohol as organic substrate. The organic compounds were extracted after irradiation reaction and subjected to NMR experiments, which revealed that the conversion of the compounds were highly efficient and selective(>99%). For instance, when benzhydol was used, the turnover numbers(TONs) reached up to304 after irradiation. Control experiments have also proved that the oxidation reaction was realized with the prepared complex as the catalyst.2 We have prepared inorganic Co P and Cd S materials and characterized their structures and morphologies by XRD,SEM 、TEM and EDX experiments. The prepared materials were milled to form a photocatalyst/cocatalyst hybrid material and were tested for visible light driven organic conversion experiment in pure water,without use of any organic solvents or compounds save the substrate and converted product. The reaction could take place in neutral conditions excluding the use of sacrificial agents and with only H2 as the byproduct. The photoredox system is easily operable and recyclable, which is environmental friendly and green. We have conducted a series of control experiments to optimize the reaction conditions and eventually we chose 2mg Co P/Cd S( 5%) hybrid material as the most effective sample catalyst for light driven alcohol conversion reaction under 3W LED light irradiation condition. Also, six different kind of organic substrates were employedfor the oxidation reaction and the reaction was highly efficient. For instance, more than >40% methylbenzyl alcohol could be converted after only 5 hours of irradiation with a selectivity >99%, and a conversion efficiency of ?mol/mg·h was obtained.The mechanistic insights were investigated by a series of time-controlled NMR, ESI and ESR methods.