Singlet oxygen generation proportion from triplet state of porphyrin in water.

[Display omitted] • The feasibility of employing Pt-TPP as a substitute for porphyrin in studying the singlet oxygen generation proportion from triplet state in water was explored and confirmed. • A first-order decay model of the excited triplet states for Pt-TPP was constructed and confirmed. • The total transition rate of the T 1 state (A 0) value under pure water content was predicted to be 0.021 μs−1. • Combined with A 0 and the quenching rate constant of T 1 by O 2 (k q), the formula for R in relation to changes in oxygen can be deduce. 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 T 1 state (A 0) value at different water contents under anoxic environments, obtained through measuring the phosphorescence lifetime (τ p) of Pt-TPP. Combined with A 0 and the quenching rate constant of T 1 by O 2 (k q), the formula for R in relation to changes in oxygen can be deduced in pure water. [ABSTRACT FROM AUTHOR]