Theoretical Research on the Charge Transport Properties of Imidazoles Axial-Coordinated with Protoheme Molecule

The charge transport properties and the stability of imidazoles with axial-coordinated protoheme molecules have been investigated by the density functional theory (DFT) at B3LYP/6-31[Formula: see text]G(d) level. With energy of each compound, we find that all heme Fe[Formula: see text] and Fe[Formula: see text] complex compounds axially coordinate the imidazoles by strong field in low-spin state. Meanwhile, binding energies were calculated, the structure feature and the frontier orbital distribution of complex compounds were also analyzed. On the basis of Marcus theory, the reorganization energy, matrix element and charge transport rate constant were calculated. The results show that the charge transport rate of the complex compound coordinated imidazole is greater than that of the complex compound coordinated 2-methyl imidazole, which indicates that the charge transfer between the imidazole and the heme iron is more favorable to the heme iron than the 2-methyl imidazole. The results are in good agreement with the experimental ones obtained by Battistuzzi.