| Autor: |
Ushakov, E., Gromov, S., Kuz"mina, L., Vedernikov, A., Avakyan, V., Howard, J., Alfimov, M. |
| Zdroj: |
Russian Chemical Bulletin; July 2004, Vol. 53 Issue: 7 p1549-1562, 14p |
| Abstrakt: |
The structure of the E,Eisomer of a butadienyl dye of the benzothiazole series containing a 15-crown-5 fragment was established by X-ray diffraction analysis. The stacking motif of the dye molecules in the crystal structure is, apparently, attributable to intermolecular π-interactions between the large conjugated fragments. The possibility of [2+2] photocycloaddition occurring in the crystal is discussed. Reversible geometrical photoisomerization of the dye and its complex with Mg2+in acetonitrile solution was studied by spectrophotometry and 1H NMR spectroscopy. Photoirradiation of the complex of the E,Eisomer with Mg2+leads predominantly to isomerization of the C=C bond adjacent to the benzothiazole fragment. Regioselective E,E→Z,Ephotoisomerization occurs viaa singlet mechanism with a quantum yield of about 0.45. The quantum yield of reverse Z,E→E,Ephotoisomerization is approximately 0.52. The structures of different geometrical isomers of the dye complex with Mg2+were calculated by the quantum-chemical density functional theory (DFT). |
| Databáze: |
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