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Indian Journal of Chemistry -Section B (IJC-B) >
IJC-B Vol.46B [2007] >
IJC-B Vol.46B(11) [November 2007] >
| Title: | Wavelength dependent regioselective E→Z isomerization of 9-anthryldiene derivatives |
| Authors: | Reddy, Majjigapu Janaki Ram
Kumar, Perepogu Arun
Srinivas, Uppalanchi
Reddy, Vummadi Venkat
Reddy, Maruthi Janaki Ram
Rao, G Venugopal
Rao, Vaidya Jayathirtha |
| Keywords: | Anthryldienes
Photoisomerization
Wavelength dependence
Regioselectivity
Charge transfer
Fluorescence |
| Issue Date: | Nov-2007 |
| Publisher: | CSIR |
| Abstract: | 9-Anthryldiene derivatives 1-5 are synthesized to study E→Z photoisomerization. Photoisomer composition upon direct excitation, and triplet-sensitized isomerization are determined. Quantum yield of isomerization, quantum yield of fluorescence and fluorescence life times are determined for these compounds. Interestingly, upon direct excitation the anthryldiene derivatives 1-3 carrying electron withdrawing end groups (EWG) displayed wavelength dependent regioselective E→Z isomerization from the singlet excited state. Triplet sensitization studies revealed that these anthryldiene derivatives undergo Z→E isomerization and not E→Z isomerization. The dual fluorescence observed for 1, 2, 3 and
2E, 4Z-1, indicates the involvement of two different emissive states. The fluorescence solvatochromism displayed by 1, 2, 3 and 2E, 4Z-1 is a clear indication of the involvement of a highly polarized/charge transfer singlet-excited state and the same is involved in the isomerization process. Fluorescence lifetimes measured for these compounds displayed bi-exponential behavior supporting the presence of two emissive states. A mechanism for photoisomerization is suggested. |
| Page(s): | 1833-1847 |
| ISSN: | 0376-4699 |
| Source: | IJC-B Vol.46B(11) [November 2007]
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