Structure modification of electron states of
Mg-a-NO2-porphin molecule
in external uniform electric field
V.A.Kuzmitsky, V.I.Gael, A.S.Mazurenko
CNDO/S quantum chemical calculations of the Mg-a-NO2-porphin molecule in external uniform electric field E have been carried out. It is supposed that the field E is directed from the NO2 group to porphin ring and its magnitude is varied from 0 up to 0.01 a.u. In addition to the Q and B levels, two electron transfer levels from the porphin macrocycle to the NO2 group in zero field arise at 17000 and 21000 cm-1 . As follows from the calculations the energy of the unoccupied molecular orbital located on NO2 abruptly falls down as E increases. This brings about on energy decrease of the intermolecular charge transfer states and on their mixing with the S and T local excited states of the porphin ring. It is shown that the behavior of the charge transfer levels depends on dihedral angle between the planes of the porphin ring and the NO2 group (q). The Q1-level and CT1-level quasi-crossing exists at E = 0,002 a.u. (q= p/4). The deactivation pathways of electron excitation of nitroporphirins are qualitatively discussed.