Poly(4-vinylpyridine) was determined to possess conductivity in the experiment. In order to understand properties of the polymer, a series of 4-vinylpyridine oligomers were designed. The structures of these oligomers were optimized using density function theory (DFT) at B3LYP/6-31G(d) level. The energy gaps and thermal stabilities of the oligomers were decreased when the chain lengths were increased. These properties were also decreased owing to the protonation of the pyridine ring. The holes were easily injected into the oligomers in the presence of hydrochloride. The electrons were conducted in the side chain composed of the pyridine rings rather than the main chain owing to the saturation of the main chain. The ¹³C nuclear magnetic resonance (NMR) spectra and nucleus independent chemical shifts (NICS) of these compounds were calculated at B3LYP/6-31G(d) level. The chemical shifts of the carbon atoms connected with the nitrogen atoms in the protonated pyridines were moved upfield in comparison with those of the pyridines. The addition of hydrochloride on the pyridine ring in the oligomers led to the increase of the aromaticities, namely the aromaticities of the oligomers were obviously improved when the pyridine rings were protonated.

The computational models for a series of PPV (para-phenylenevinylene) oligomers were formed based on the biphenyl and stilbene structures. These oligomers were optimized using DFT at B3LYP/6-31G (d) level. On the basis of the optimized geometries, the electronic spectra and ¹³C NMR spectra were calculated by the INDO/CIS and B3LYP/6-31G(d) methods, respectively. It indicates that the main absorptions in the electronic spectra are red-shifted when the oligomer length is increased. The main absorptions in the electronic spectra and the ¹³C chemical shifts are altered obviously when the substituents on the matrix are changed.

Hydrogen bonds play important roles to living organisms containing pyrimidine-based derivatives. The electronic structures of the hydrogen bonding complexes formed by 2,4-bis(acrylamido)pyrimidine (2,4-BAAP) derivatives with 1-substituted uracil were studied using Austin Model 1 (AM1) and density function theory (DFT) methods. The UV and NMR spectra of the complexes were calculated with the INDO/CIS (configuration interaction for singlet in intermediate neglect of differential overlap) and B3LYP/6-31G(d) methods. It was shown that the complexes could be formed via the triple hydrogen bonding between two monomers owing to the negative binding energies. The binding energies of the complexes were weakened in the presence of substituents, but this weakening effect depended on the simultaneous influence of the electronic and steric effects. The binding energies of the complexes were also decreased owing to the formation of the isomeric complexes in the presence of piperidyl on 2,4-BAAP. The energy gaps of the complexes were lessened in the presence of electron-donating groups. Holes and electrons were easily injected to the complexes due to the extension of the conjugation chain. The first UV absorptions of the complexes relative to those of the parent compound were red-shifted because of the narrow energy gaps. The chemical shifts of the carbon atoms on the CO bonds in the complexes were changed downfield.