A. Suvitha1, R. V. Belosludov1, H. Mizuseki1, Y. Kawazoe1, M. Takeda2, M. Kohno2 and N. Ohuchi3
1Institute for Materials Research, Tohoku University, Sendai 980-8577
A theoretical study has been performed on a hematoporphyrin and its dimers which are components of Photofrin, a photosensitizer. Full geometry optimizations have been carried out using the PBEPBE functional and 6-31 G(d) basis set. This combination gives better agreement with X-ray crystal data of porphyrin. Among the dimers studied, the C-C linked structure is found to have the highest stability. The predicted change of free energy (Δ G=-13.9 kcal/mol) suggests that the interconversation of ester to ether would be thermodynamically favorable. The time-dependent density functional theory (TDDFT) studies show that Q-band absorption maxima undergo a less intense transition and low oscillator strength, indicating that dimers have activity when treated under higher dosage.
hematoporphyrin, time-dependent density functional theory (TDDFT), photodynamic therapy, spectroscopy
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