Oxidation effect on double H-bonded imidazole–adenine–imidazole trimer

The geometry, the IR spectra, the molecular orbital, and the related energy of the planar double hydrogen-bonded imidazole–adenine–imidazole trimer are investigated employing the reliable B3LYP/6-311+G* method. The H bonds generated by NH group of adenine reduce significantly upon oxidation and the H atoms transfer in different degree for three isomers. Significant IR spectra red-shift occurs upon oxidation for all N–H···N H bonds. The HOMO orbital is employed to explain the variation of H-bond alkalescence, as is effective to reveal the geometry variations and the IR spectra shifts. The adiabatic ionization potential obtained in experiment should be lower than our reported value for the possible higher degree of polymerization.