Synthesis, characterization, and properties of a new thiophene-benzobisthiazole copolymer

Stille coupling reaction of 4,8-dibromo-2,6-dihexyl-benzo[1,2-d:4,5-d']bisthiazole and 2,5-bis(trimethylstannyl)thiophene afford a new conjugated conducting copolymer 1. The polymer was completely soluble in common organic solvents. The electrical conductivity of the polymer is at about 3.8x10(-1) S/cm. The UV-vis spectra of the polymer in a chloroform solution and in a spin-cast film on a piece of glass show pi-pi* absorption bands (lambda(max)) of 460 nm and 538 nm, respectively. The 78 nm red shift of the lambda(max) of the polymer in the film, in comparison to that observed for the polymer in chloroform, possibly indicates much more planarization and aggregates formation due to the pi electron stacking in terms of inter-chain characteristics in the solid state. The structure of the polymer has been compared with that of compound 3 as model compound. Rationalizations are presented for optical properties of the polymer in relation to polymer structure. (C) 2005 Elsevier B.V. All rights reserved.