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Updated: Aug 13, 2026

Ultrafast Time-resolved Near-IR Stimulated Raman Measurements of Functional π-conjugate Systems
Published on: February 10, 2020
Triplet state spectra and dynamics of geometric isomers of carotenoids
Zeus D Pendon1, Ineke der Hoef, Johan Lugtenburg
1Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060, USA.
Abstract:
The observation of preferential binding of cis-carotenoids in purple bacterial photosynthetic reaction centers versus trans-isomers in antenna pigment protein complexes has led to the hypothesis that the natural selection of stereoisomers has physiological significance. In order to test this hypothesis, we have undertaken a systematic series of investigations comparing the optical spectroscopic properties and excited state dynamics of cis and trans isomers of carotenoids. The present work compares the triplet state spectra, lifetimes, and energy transfer rates of all-trans-spheroidene and 13,14-locked-cis-spheroidene, the latter of which is incapable of isomerizing to the all-trans configuration, and therefore provides a unique opportunity to examine the triplet state properties of a structurally stable cis molecule. The data reveal only small differences in spectra, decay dynamics, and transfer times and suggest there is little intrinsic advantage in either triplet energy transfer or triplet state decay arising from the inherently different isomeric forms of cis compared to trans carotenoids.
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