| The phenol ligands with -NH2 group were linked with the Ru(Ⅱ) tris-bipyridine to construct 21 and 22. And the two compounds are coordinated manganese, ruthenium and ferric respectively, to construct other six complexes. Their redox potentials, luminescence intensities, lifetimes, quantum yields, time-resolved absorbance, transient absorbance, kinetics decay and electron transfer are studied by use of cyclic vottammetry, photoluminescence analysis and nanosecond laser flash photolysis.Although the exact mechanism of photosynthetic water oxidation is not solved, it is clear that the Mn ions in the higher oxidation states of the S-cycle are at the MnⅢ state or higher. In order to get a Mn (Ⅲ,Ⅲ) dimmer complex with high oxidation states of manganese to increase the possibility of storing more oxidizing equivalents necessary to oxidize water evolving oxygen, some pyridyl groups in Hbpmp are replaced by anionic phenolate groups as compounds 21, 22. Simultaneously, the stronger coordinate band O-Mn than N-Mn prevents dissociation of the Mn dimmer in aqueous solution (which is a problem with dpa-based systems). Introduction of tert-butyl groups to the ligand not only improves the solubility of complex, but also mcreases their electron donating effect that may result in lower redox potentials for the manganese redox complex. The two"out-standing" arms of morpholine on tert-Butyl-phenol was expected to provide the function of anchoring water via a chain "N…H-O-H…N" by the hydrogen bound function between two nitrogen atoms in morpholine and two hydrogen atoms in water.The maximum of the MLCT at two compounds 21, 22 are red shifted with the respect to that of Ru(bpy)3. These spectra variances are due to the different ligands in the compounds. Through the laser flash photolysis, the results mean the regeneration of Ru(Ⅱ) is due to the intramolecular electron transfer from the substituted phenol(s) to the photooxidized Ru(Ⅲ). And the electron transfer rate is almost two orders of magnitude faster than that of the compound 20. The hydrogen-banding between the pyridine and the phenol group could be responsible for the fester electron transfer, analogous to the proposed interaction between tyrosine and His190 in PSII. In addition, we present two new compounds 29, 30, in which the ligands are linked to ruthenium tris-bipyridine with four ester groups. The ester groups on the bipyridyl ligands provide a possibility to attach these compounds to TiO2. When the hydrolyzed compound 29 was attached to TiO2, fast intermolecular electron transfer observedhere can efficiently compete with charge recombination between oxidized sensitizer and reduced semiconductor TiO2, which provide a possibility to attain a long lifetime of charge-separated state.We coordinate Mn, Ru and Fe into the ligand 21, 22 to construct the metal complexes M2-[RuⅡ(bpy)3]. According to the fitting of 470 nm trace in complex 32, RuⅡ recovery occurred with kET> 8.2 ×107 s-1. We attribute this to intramolecular electron transfer from the Mn2(Ⅲ,Ⅲ) moiety, most likely generating the Mn2(Ⅲ, Ⅳ)complex. And in complex 33, the transient absorption data indicate that, Ru(Ⅱ) can be photooxidized to Ru(Ⅲ) and then reduced by very fast intramolecular electron transfer from the coordinated dinuclear ruthenium moiety. The above results demonstrate that these complexes can be applied for photo-induced oxidized models research.
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