Analysis of chitosan/polyvinylpyrrolidone (structure, ftir, electrostatic potential, homo/lumo orbitals) using computational chemistry

Chitosan and PVP oligomers were analyzed by means of the HyperChem software 8.0v to determine the theoretical structure. Quantum chemical calculation of geometrical structure and energies were studied using PM3 and AM1 methods in where the Gibbs free energy was calculated with a value of -9028 and -5796 Kcal/mol, respectively; these values showed that the reaction was carried out. Quantum chemical calculations are applied to study the (CT) complexes in order to obtain information on structures and other molecular properties like specific interaction of donor and acceptor. The interaction energy contribution comes from the effects of donor- acceptor interactions and π-π interactions. The HOMO and LUMO were simulated by determinate the transition state and energy band gap. Vibrational analysis shows that the band in 3185 cm-1 and shifting of band to lower wave number clearly indicates strong intermolecular interactions between chitosan and PVP. When the PVP oligomers is blended with chitosan, this absorption signal, which is assigned to the stretching vibration of a C=O group in the pyrrolidone ring, tends to shift to a position of somewhat lower frequency.