Thiosubstituted carbonyl systems have attracted significant due to their strong influence on chemical properties in both electronic ground and excited states. Thiosubstituted nucleobases, in particular, have been studied extensively for their biological significance and applications in photochemotherapeutics. Many of these photo-induced processes are driven by intersystem crossing (ISC) and non-adiabatic dynamics in triplet states. Investigations of the electronic structures of these long-lived triplet states and understanding how the excited state dynamics (ESMD) is influenced by chemical and environmental factors can provide critical insights useful for designing photochemical processes tailored to specific applications.