Biopolymers and cell. 2006; 22 (3): 231 - 235

Possible electronic mechanisms of generation and quenching of luminescence of singlet oxygen in the course of photodynamic therapy

B. F. Minaev, L. B. Yashchuk

On the basis of ab initio quantum chemical calculations the strong enhancement of the ¹(а¹D_g·S₀)® ¹(Х³S_g^– ·T) transition in collision complex between O₂ and organic dye is predicted, where T is the triplet excited state of the dye and S₀ is its ground singlet state. The collision-induced electric dipole transition moment depends on polarizability of the dye and can be used for the estimation of energy transfer rate constant. Quantum chemical calculations can predict the most efficient dye sensibilizer for photodynamic therapy of cancer, instead of the difficult experimental search. Some new ideas are proposed for additional laser simulated mechanisms of active oxygen generation.

Keywords: singlet, triplet, complex of collision, transition moment, spin-orbit coupling.