CONFORMATIONAL ANALYSIS OF 2-ANTHRYLETHYLENE DERIVATIVES: PHOTOCHEMICAL AND COMPUTATIONAL INVESTIGATION
U. Srinivas, P. Arun kumar, Srinivas Kolupula, K. Bhanuprakash, V. Jayathirtha rao
Keywords: 2-anthryethylene derivatives, photochemical cis-trans isomerization, fluorescence, charge transfer, conformational analysis, theoretical studies
Pages: 872-886
Abstract
2-Anthrylethylene derivatives 1E-5E and 1Z are synthesized to study the cis-trans photoisomerization. Interestingly, unlike 9-anthrylethylene derivatives, 2-anthrylethylene derivatives 1E to 5E do not exhibit E (trans) to Z (cis) photoisomerization upon direct and triplet sensitization. One-way Z (cis) to E (trans) photoisomerization of 1Z is found to be very efficient under direct and triplet sensitization conditions, demonstrating the involvement of both singlet and triplet states. 1E-5E exhibits excitation wavelength dependent fluorescence indicating the existence of conformers (rotamers) at room temperature, which is confirmed by fluorescence lifetimes measurements of compounds 1E and 2E. Theoretical studies are carried out at DFT and ab initio methodology and the calculated relative energy difference of the conformers is very small; it ranges between 2.9 kJ·mol-1 to 6.3 kJ·mol-1 for both ground and excited states.
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