Synthesis and characterization of alanine functionalized oligo/polythiophenes

Abstract

The synthesis and characterization of a series of monothiophenes and terthiophenes bearing amino acids are reported. The reaction of a thiophene, substituted in position 3 by either a carboxylic acid or an acetic acid moiety, with an alanine methyl ester in the presence of hydroxybenzotriazole (HOBt) and N,N′-dicyclohexylcarbodiimide (DCC) affords several mono/terthiophene-alanine methyl esters. The latter were deprotected to form the corresponding carboxylic acids. Terthiophenes have been prepared in good yields via a Stille cross coupling reaction, using a dibromothiophene–alanine methyl ester and tri-butyl stannyl thiophene. The newly prepared monomers are very stable in air and in the presence of organic solvents. The optical and electrochemical properties of the monomers and their corresponding polymers were also examined using cyclic voltammetry and indium tin oxide (ITO) electrodes.