A systematic study of a class of divalent transition-metal texaphyrin complexes (M-Tex+, M = Mn, Fe, Co, Ni, Cu, Zn), recently proposed as active photosensitizers in photodynamic therapy (PDT), was undertaken for the ground and excited electronic states. Geometry optimizations were performed by using the PBE0 exchange-correlation functional coupled with the 6-31G(d) basis set, while electronic excitations energies were evaluated by means of time-dependent density functional response theory (TD-DFT) at the PBE0/6-31+G(d) // PBE0/6-31G(d) level of theory. Solvent effects on excitation energies were taken into account in two ways:  by considering solvent molecules explicitly coordinated to the metal center and as bulk effects, within the conductor-like polarizable continuum model (C-PCM). The influence of the metal cation on the so-called Q-band, localized in the near-red visible region of the spectrum, was carefully examined since it plays a basic role in the drug design of new photodynamic therapy photosensitizers. The differences between experimental and computed excitation energies were found to be within 0.3 eV.

Absorption Spectra of the Potential Photodynamic Therapy Photosensitizers Texaphyrins Complexes: A Theoretical Analysis

LELJ GAROLLA DI BARD, Francesco
2007-01-01

Abstract

A systematic study of a class of divalent transition-metal texaphyrin complexes (M-Tex+, M = Mn, Fe, Co, Ni, Cu, Zn), recently proposed as active photosensitizers in photodynamic therapy (PDT), was undertaken for the ground and excited electronic states. Geometry optimizations were performed by using the PBE0 exchange-correlation functional coupled with the 6-31G(d) basis set, while electronic excitations energies were evaluated by means of time-dependent density functional response theory (TD-DFT) at the PBE0/6-31+G(d) // PBE0/6-31G(d) level of theory. Solvent effects on excitation energies were taken into account in two ways:  by considering solvent molecules explicitly coordinated to the metal center and as bulk effects, within the conductor-like polarizable continuum model (C-PCM). The influence of the metal cation on the so-called Q-band, localized in the near-red visible region of the spectrum, was carefully examined since it plays a basic role in the drug design of new photodynamic therapy photosensitizers. The differences between experimental and computed excitation energies were found to be within 0.3 eV.
2007
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11563/1173
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