Spatial Factors for Triplet Fusion Reaction of Singlet Oxygen Photosensitization

Shuming Bai (1) , Mario Barbatti (1)

1 ICR - Institut de Chimie Radicalaire

First-principles quantum-chemical description of photosensitized singlet oxygen generation kinetics is challenging due to the intrinsic complexity of the underlying triplet fusion process in a floppy molecular complex with open-shell character. With a quantum-chemical kinetic model specifically tailored to deal with this problem, the reaction rates are investigated as a function of intermolecular incidence direction, orientation, and distance between O2 and the photosensitizer. The adopted photosensitizer, 6-azo-2-thio-thymine, combines practical interest and prototypical variability. The study quantitatively determined maximum singlet oxygen generation rates for fifteen incidence/orientation directions, showing that they span five orders of magnitude between the largest and the smallest rate. Such information may provide a hands-on guideline for the experimental molecular design of new photosensitizers as well as further higher-level theoretical research. TOC graph

Mots clés: kinetic model; photosensitization; triplet fusion; singlet oxygen

Domaines: Chimie théorique et/ou physique

Shuming Bai, Mario Barbatti. Spatial Factors for Triplet Fusion Reaction of Singlet Oxygen Photosensitization. Journal of Physical Chemistry Letters, 2017, 8 (21), pp.5456-5460. ⟨10.1021/acs.jpclett.7b02574⟩. ⟨hal-02288769⟩