Ultrafast internal conversion in neobetanin in comparison to betacyanins / Monika Wendel, Stanislaw Nizinski, Dorota Prukala, Marek Sikorski, Slawomir Wybraniec, Gotard Burdzinski // Journal of Photochemistry ... więcej

Ultrafast internal conversion in neobetanin in comparison to betacyanins / Monika Wendel, Stanislaw Nizinski, Dorota Prukala, Marek Sikorski, Slawomir Wybraniec, Gotard Burdzinski // Journal of Photochemistry and Photobiology A: Chemistry [Dokument elektroniczny]. – 2017, Vol. 332, s. 602-610 : schem., tab., wykr. – Tryb dostępu: http://www.sciencedirect.com/science/article/pii/S1010603016305366. – Bibliogr. 59 poz., Abstr. – Data publikacji postprintu: 2016-10-05. – doi: 10.1016/j.jphotochem.2016.09.027. – ISSN 1010-6030

The photophysics of neobetanin (14,15-dehydro-betanin) is compared to that of the structurally similar betacyanins. The dye S1 state lifetime in solution depends on the solvent viscosity, the strength ... więcej

The photophysics of neobetanin (14,15-dehydro-betanin) is compared to that of the structurally similar betacyanins. The dye S1 state lifetime in solution depends on the solvent viscosity, the strength of solute-solvent hydrogen bonds and the possibility of intramolecular hydrogen bonds formation. The S1 state lifetime of neobetanin is surprisingly short (2.3 ps in H2O), compared to betanin and isobetanin (6.4 ps), despite the largest energy gap E(S1-S0) = 19100 cm-1 measured for neobetanin. The decay of S1 to S0 state proceeds through the internal conversion, preceded by a large-amplitude motion, probably involving twisting around the carbon-nitrogen and carbon-carbon bonds in the central part of the dye molecule. The internal conversion produces the nascent twisted neobetanin in its S0 state, with a transient band at  = 540 nm in H2O, and 3.8 ps lifetime determined in pump-probe experiments. The respective transients are clearly observed for betanin and isobetanin in the pump-dump-probe experiments.