A Study on the structure and reactivity of encounter complex

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It has been thought that the tris-chelate metal-complexes of mixed-ligands of some poly-pyridines are completely spherical in chemical reaction in solution. However, the experimental results of energy-transfer rate-constant from the mixed-ligand Ru(II)-complex to Cr(III) complex indicate that the energy-acceptor complexes do not exist around the mixed-ligands complexes of energy-donor in encounter complex in aqueous solution. In other words, the relative geometry between the mixed-ligand Ru(II)-complex and Cr(III) complex are not isotropic but anisotropic even in encounter complex in solution. The congeniality between donor's ligand and acceptor's ligand is very important for the structure of encounter complex in aqueous solution, for example, hydrophobicity and hydrophilicity.In mixed-solvents of water : ethanol and water : acetonitrile (v.v. 8 : 2 and 6 : 4), the relative geometry of encounter complex is different from that in aqueous solution. These results indicate that the solvent molecules of ethanol and acetonitrile affect on the relative geometry of encounter complex.Therefore, the determination of the rate-constant of photo-excitaion energy-transfer between metal-complexes makes it possible for the structure of encounter complex in solution as molecular level.The results in this work have a very wide application, especially in the region of chemical reaction in a living body.