| Research Abstract |
This study was been carried out in order to synthesize photochromic Ag(I) complexes and to clarify the structure and physical property. Four Ag(I) complexes with cis-dbe [Ag2(cis-dbe)(X)2](X : CF3SO3(1), CF3COO(2), C2F5COO(3), C3F7COO(4) were synthesized using photochromic cisdbe as ligand and the structures were determined by single crystal X-ray structure analysis, where cis-dbe represents cis-1, 2-dicyano-1, 2-bis(2, 4, 5-trimethy1-3-thienyl)ethane. In each complex Ag ion coordinates to cyano and thienyl groups from different cis-dbe to forme one-dimensional chain structure. CF3SO3 and CF3COO bridge two Ag ions within the chain, whereas C2F5COO and C3F7COO bridge two Ag ions etween the neighboring chains to give a two-dimensional sheet.
Distance between reactive sites, that is, the distances between C…C or which the carbons kewly generates a σ-bond to form the ring-closed form of cis-dbe are 3.58, 3.51, 3.45 and 3.49Å complexes 1, 2, 3, and 4, respectively. It is considered that the
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quantum yield of the reaction increases, as it is shorter. However, there seem to be small difference in the quantum yield of ring-closed photoreaction of 1〜4 complexes, since the reactive site distance are within 3.45〜3.58Åand the difference is slight. The effect of Ag-S bond and steric hindrance on the rotation of thienyl groups is shown to be smallest in 3 and it is proven that 3 can be expected as an optical memory device.
The excitation state was calculated by configuration interaction (CI) method using the molecular structure. From the calculation result of orbital energy, the photocyclization reaction accompanying the rotation of the thienyl groups occurs, after it is excited from HOMO to LUMO in the singlet state, and in this time the symmetry of the orbital is inverted between HOMO and LUMO. The reaction analysis of excitation state by CI method shows that the excitation wavelength from HOMO in the ring-closed form is in long-wavelength side compared with ring-open form. The result qualitatively coincides with experimental value. Less
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