ADVANCING MOLECULAR PHOTOCHEMISTRY: TRIPLET EXCITED STATES AND THEIR APPLICATIONS IN ORGANIC SYNTHESIS AND PHOTODYNAMIC THERAPY

Abstract

The study explores the contributions and applications of triplet excited states in both molecular photochemistry, organic synthesis and photodynamic therapy. In particular, PS-4 possessed longer triplet lifetimes and higher quantum yield and intersystem crossing efficiency, leading to its significantly more favorable efficiency over the other newly synthesized photosensitizers in the research. The catalytic performance was highlighted by experimental findings in photochemical reactions such as [2+2] cycloaddition and singlet oxygen oxidation under [CuI] catalysis, which showed superior selectivity and yield. The study also demonstrated the cytotoxic effects of photosensitizers on multiple types of cancer cells, with PS-4 producing highly considerable apoptotic events on cancer cells while remaining minimally toxic to normal cells for the photodynamic therapy of tumors. Stability analyses showed that molecular functionalization resulted in enhanced post- excitation photo stability, necessary for prolonged applicability in bio-medical and industrial uses. The results confirm the key function of triplet states in promoting photochemical reactivity and put forward the potential of structural engineering of photosensitizers for further development in green chemistry and selective cancer therapy. Although these results are very promising, limitations of controlled experimental conditions and unaddressed long-term in vivo toxicity present the need for further study. Future directions can include computational modeling to further optimize photosensitizer structures, broaden therapeutic applications, and explore hybrid systems to overcome limitations of singlet oxygen sensitivity and efficiency. In conclusion, this study sheds new light on rational design of photosensitizers, which will benefit the next-generation of photochemical and biomedical technologies.