Photosynthetic antenna mimics, energy

Li and coworkers49 reported a molecular motion of /1-carotene and a carotenopor-phyrin dyad (composed of a porphyrin, a trimethylene bridge and a carotenoid polyene) in solution. Internal rotational motions in carotenoid polyenes and porphyrins are of interest because they can mediate energy and electron transfer between these two moieties when the pigments are joined by covalent bonds. Such internal motions can affect the performance of synthetic model systems which mimic photosynthetic antenna function,... 

Cyclodextrins can be functionalized with various types of chromophores on both the primary and the secondary hydroxyl rims. A review of the prepared, selectively 0-substituted, CDs has been published [204], The modified CDs show interesting photochemical properties which have been exploited to detect photochemically inactive organic compounds in aqueous solutions [205], to induce stero- and regioselectivity in some photochemical reactions, and to mimic the energy transport from the antenna to the reaction center in the photosynthetic membrane (vide infra). 

The assembly of molecular components for light harvesting and charge separation in artificial photosynthetic systems is of current interest. To mimic the multistep electron transfer in natural systems, Imahori et al. prepared a mixed SAM that combines an artificial antenna system (pyrene) with an artificial reaction centre (porphyrin), to examine the possibihty of photoin-duced energy transfer in two-dimensional assemblies (Fig. 29, 20) [27,147]. The ratio of porphyrin pyrene in the mixed SAM estimated from the absorption spectra on the gold surface is significantly lower than that of the solution from which the SAM was prepared. The strong tz-tz interaction of... 

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