Singlet oxygen generation proportion from triplet state of porphyrin in water

The proportion of singlet oxygen (R) produced from the triplet state of porphyrin in aqueous solutions was investigated by substituting porphyrin molecules with the metalloporphyrin Platinum(II) meso-tetraphenylporphyrin (Pt-TPP). The feasibility of using platinum porphyrin as a substitute for porphyrin to study the photophysical properties in photodynamic therapy (PDT) was confirmed. The model of first-order decay in a water-methanol mixed solution encompasses potential deactivation processes of the excited triplet states and was built, which was confirmed by monitoring the change in the total transition rate of the T₁ state (A₀) value at different water contents under anoxic environments, obtained through measuring the phosphorescence lifetime (τ_p) of Pt-TPP. Combined with A₀ and the quenching rate constant of T₁ by O₂ (k_q), the formula for R in relation to changes in oxygen can be deduced in pure water.