Theoretical design of novel selenium-substituted meso-aryl-BODIPYs as singlet‑oxygen photosensitizers with biomedical applicability

This is a DFT study on selenium-substituted meso-aryl-BODIPYs aimed at designing novel singlet-oxygen photosensitizers with potential biomedical applicability. Three different selenium-containing heterocycles (2,3-dihydro-1,3-selenazole, 1,3-oxaselenole and 1,3-thiaselenole) were combined with diverse types of meso-aryl-BODIPYs. The incorporation of selenium atoms into BODIPYs is a novel strategy to enhance the photosensitizer performance, reducing the toxicity associated with the use of metal atoms. The present study provides new perspectives on the use of these novel agents which have been scarcely developed to date. Diverse electronic descriptors such as the absorption maxima wavelength, singlet-triplet energy gap and spin-orbit coupling were used in subsequent screening steps to select the most suitable candidates as photosensitizers with biomedical applicability. These descriptors are related to the light absorption within the therapeutic window, the triplet-state formation efficiency, the triplet-state lifetime and the energy transfer to the molecular oxygen.