Once ISC occurs, the compounds could transfer energy to molecular oxygen for the generation of singlet oxygen through a spin-exchange reaction (reaction 3 in Scheme 1). To verify this possibility, the T1→S0 vertical energy gap at the T1 minimum of each compound (acting as a photosensitizer) was calculated. The results are presented in Table . They show only a slight dependence on the type of solvation treatment. (¹Δg and ¹Σg⁺), respectively, S1 and S2. Analyzing the vertical T₁→S₀ energy gap (Table ), we observe that THP and resveratrone have enough energy to excite the 3 O2 to both singlet states. Although we have already discarded cis-and transresveratrol as photosensitizers, we can still extend this energy analysis to them.