CLEAR EVIDENCE OF THE SENSITIVITY OF THE SOLVATOCHROMIC EFFECT TO SIDE-CHAIN FUNCTIONALIZATION IN 3-HEXYL-SUBSTITUTED POLYTHIOPHENES

The solvatochromic properties of 3-hexyl-substituted polythiophenes fu nctionalized with an ester, ether or hydroxy group at the end of the a lkyl side chain are reported. An extraordinarily large shift, Delta la mbda(max) = 99 nm, and a dramatic change of the UV/vis spectral profil e are found when the carboxylate is replaced with the hydroxy group by functionalization exchange. The solvatochromic behavior of each polym er is believed to be strictly related to the type of functional group owing to different physical interactions (solvation) between groups di fferent in polarity and solvent molecules. A unique and common chromop horic unit for the final conformation of the 3-hexyl-substituted polyt hiophenes, induced by the solvatochromic effect, is also suggested.