DFT calculations of the local spin densities and oligomerization mechanism of thiophene-phenylene (TP) co-oligomers and derivatives

In this work we are going to combine the DFT calculations with experimental results on three types of copolymers based on phenylene and thiophene. First and for obtaining a theoretical basis for the one-step formation of poly(2-phenylthiophene) (TP) and derivatives. The electronic states of three monomers based on thiophene and phenylene (TP) were elucidated by molecular orbital calculations using DFT (B3LYP/6-31G∗). Then, the reactivity for coupling reaction of TP and derivatives are inferred from the unpaired electron spin densities of the respective radical cations. The major regio-selective product of the polymerization can be well understood in term of the magnitude spin densities. Our goal is initially to propose an oligomer model by examining the initiating and propagating reaction based on this theoretical study. Then, to investigate the effect of alkyl and alkoxy groups, attached on phenylene ring, on various properties of copolymer by examining structural and electronic properties.