Modeling the potential use of polyfluorinated phthalocyanines as photosensitizers in photodynamic therapy

Abstract

In recent years, phthalocyanine compounds which possess an aromatic macro cyclic ring, have been extensively used in photodynamic therapy as non-toxic photosen sitizers due to their photophysical properties and their intense absorption in the near infrared region of the visible spectrum. However, there may be predominant factors such as metal ion, substituent effects that enhance the efficiency of phthalocyanines as photosensitizers and they have considerable influence on the excited state proper ties, electronic spectra, intersystem crossing probability. They ultimately determine the phthalocyanine propensity to activate the singlet oxygen which is held respon sible for cell death. A theoretical evaluation of photophysical properties could give preliminary hints about the singlet oxygen generation ability. In this study, Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TDDFT) at ωB97XD/6-311G**//B3LYP/6-31G* level of theory has been used to elucidate the optical properties of pentafluorobenzyloxy- substituted phthalocyanines as well as of their unsubstituted analogues. To achieve the dynamic effects in absorption and emis sion spectra, Wigner Distribution has been used by sampling the excited state and ground state geometries.