Quantum yields of singlet oxygen of tetrakis (4-carboxyphenyl) porphyrin in different solvents

The singlet oxygen quantum yields of photosensitizers in different solvents are very important for photodynamic therapy (PDT). Here, we investigated the singlet oxygen quantum yields of tetrakis (4-carboxyphenyl) porphyrin (TCPP) in various solvents by the iodide method. Results indicate that TCPP has different singlet oxygen formation efficiency in different solvents. When compared to TCPP dissolved in water, TCPP showed higher singlet oxygen yields in methanol and ethanol, but lower singlet oxygen yields in DMF under identical conditions. In particular, TCPP rapidly precipitated in acetone after potassium iodide added in the solution. The salting out effect of TCPP by potassium iodide in acetone was confirmed by re-dissolving the precipitation in water and the characteristic absorption of TCPP was measured. The phenomenon of salting out for TCPP in acetone suggests that acetone is not a good solvent for singlet oxygen generation when evaluated by the iodide method.