Synthesis and characterization of chiral polythiophenes : Poly [(R)-(-) and (s ) -(+ ) -2 -(3' -thienyl )ethyl N-(3 ,5 -dinitrobenzoyl ) -α -phenylglycinate]

Abstract ( R )-(−) ( 1 ) and ( S )-(+)-2-(3′-Thienyl)ethyl N -(3″,5″-dinitrobenzoyl)-α-phenylglycinate ( 2 ) monomers were synthesized, characterized, and polymerized in chloroform using FeCl 3 as an oxidizing agent. Molecular weights of 2.6 × 10 4 and 3.2 × 10 4 for poly1 and poly2 , respectively, were determined by SEC analysis. FTIR spectra of the polymers indicated the coupling of monomers through the α positions. UV–vis spectra showed absorption bands at λ max  = 226 and 423 nm for poly1 and poly2 , ascribed to transitions of side groups and polythiophene backbone, respectively. Poly1 and poly2 remained stable up to 210 °C. At higher temperatures, a two step weight loss degradation process was observed for both polymers by TGA analysis. 1 H NMR, in the presence of Eu(tfc) 3 , and optical rotation measurements indicate the chiral properties of the monomers 1 ([α] D 28  = −76.2) and 2 ([α] D 28  = +76.0), and the maintenance of chirality after polymerization ( poly1 [α] D 28  = −29.0 and poly2 [α] D 28  = +28.4, c  = 2.5 in THF). According to scanning electron microscopic analysis, the polymers are highly porous.