Mini-carotenes

Unlike Andersson et al. (1995), Frank et al. retain the AE s estimated from the original 77 K spectra of the two mini-carotenes and relate these energies to lifetimes obtained in room temperature solutions. Future applications of the energy-gap law to estimate S, energies in nonfluorescent carotenoids should carefully consider how ki, and AE (and the parameters obtained from Eqs. (3) and (4)) depend both on solvent and on temperature. 

Andersson PO, Gillbro T, Ferguson L and Cogdell RJ (1991) Absorption spectral shifts of carotenoids related to medium polarizabihty, Photochem Photobiol 54 353-360 Andersson PO, Gillbro T, Asato AE and Liu RSH (1992) Dual singlet-state emission in a series of mini-carotenes. J Luminescence 51 11-20... 

Sashima, T., Koyama, Y., Yamada, T., and Hashimoto, H. 2000. The lBu+, lBu", and 2Ag" energies of crystalline lycopene, P-carotene, and mini-9-P-carotene as determined by resonance-Raman excitation profiles Dependence of the I IUi state energy on the conjugation length../. Phys. Chem. B 104 5011-5019. 

Steric crowding in the cis isomer of Mini-3 (16), a chain shortened triene analog of -carotene, and hexakis (2,2/,4,4/,6,6/-trifluoromethyl)stilbene (17) forces the polyene chromophores to adopt a spiral conformation. Some of the associated unusual spectroscopic properties (UV-VIS and NMR) of these compounds and a rare 1,7-H shift process were described. 

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