Structural and Electronic Properties of Crown Ether Functionalized Oligothiophenes

Abstract

Quantum mechanical calculations at the B3LYP level combined with the 6-31G(d) and 6-31+G(d,p) basis sets have been performed on oligomers containing n repeating units (with n ranging from 2 to 8) of three crown ether functionalized polythiophenes, which differ in the size of the macrocycle. Results have been compared with those obtained for poly(3,4-ethylenedioxthiophene), which was calculated at the same theoretical levels. Results indicate that, independently of the size of the ether macrocycle, functionalized oligomers tend to adopt an antiplanar conformation with the inter-ring dihedral angles arranged in trans. Moreover, the rotational profile calculated by scanning the inter-ring angle is not significantly influenced by neither the size of the macrocycle nor its conformation. On the other hand, the electronic properties of the crown ether functionalized polythiophenes, which were obtained by extrapolating the results obtained for the oligomers, were very similar to those of poly(3,4-ethylenedioxythi...