Structure and optoelectronic properties of helical pyridine-furan, pyridine-pyrrole and pyridine-thiophene oligomers.

Density functional theory based calculations have been carried out to systematically investigate the structural and optoelectronic properties of pyridine-furan, pyridine-pyrrole and pyridine-thiophene oligomers. Comparison of results obtained at B3LYP/6-31G(d) and B3LYP-D3/6-31G(d) levels of theories reveals that the inclusion of dispersion correction with the B3LYP functional has a major impact on ground state structures and stabilities of the most stable conformers, which are helical for our studied systems. Calculation of stabilization energies, gained due to non-bonding interaction between adjacent helical turns, shows that stabilities of helical oligomers increase with an increase in the chain length.