Synthetic study on hybrid compounds of chlorophyll and polyene having SH group

Abstract

In photosynthetic organisms, carotenoids are acting as antenna by transferring light-energy to chlorophyll to promote photosynthesis. Toward the fabrication of dye-sensitized solar cells, we tried to synthesize hybrid compounds of chlorophyll and polyenes having several conjugated systems and SH group, which is utilized for connecting polyene parts to an electrode made from gold.
As a preliminary experiment, we have established a synthetic procedure for the hybrid compound by use of a model compound having a shorter conjugated system. A conjugated allyl alcohol possessing a triisopropylsilylthio group was derived from commercially available methyl 4-hydroxymethylbenzoate via elongation of conjugated double bonds and transformation of the benzyl alcohol part to a benzyl silylthio group. This ally alcohol was condensed with porphyrin-carboxylic acid by Mukaiyama's method, and then desilylated to give a desired hybrid compound.