Potential Photosensitizers for Photodynamic Tumor Therapy—i. Photophysical Properties of Two Chlorin Derivatives

Abstract

Abstract— Photophysical properties of two chlorin type molecules (CHLI) and (CHLII) were investigated in different solvents. Quantum yields of fluorescence φF of S, → T, intersystem crossing φT, and of singlet oxygen (1Δg) formation φΔ, as well as the Stern‐Volmer constants for the quenching of the S, states by oxygen and the bimolecular rate constants of quenching of 1Δg by the chlorins were measured. The values of φT and φΛ can be given as 0.57 and 0.58 for CHLI and 0.69 and 0.58 for CHLII. The values of the fluorescence quantum yields, the strong absorption of the chlorins in the red (Λ > 630 nm) and the high values of the quantum yields for 1Δg formation recommend the chlorin derivatives as potential markers and photosensitizers for tumor therapy.

Potential Photosensitizers for Photodynamic Therapy—ii. Photophysical Properties of [26] Porphyrin

“…As discussed previously in more detail (Schermann et al, 1990) SA is identical with S A = k,/(k, + k h ) (7) for 'A, sensitizers with k$ < lo"-' sP1 . k, and kh denote the rate constants for the energy transfer process (a) and the deactivation process (b), respectively.…”

Singlet and triplet state quenching of aromatic cations by molecular oxygen

“…The apparatus for determination of triplet lifetimes by detection of transient triplet-triplet absorption was described in detail elsewhere [14]. Excitation source was a XeCl excimer laser (Lambda Physics), ,Iem = 308 nm.…”

Temperature dependence of the oxygen quenching of .pi..pi.*-singlet and .pi..pi.*-triplet states of singlet oxygen sensitizers

“…The TT absorption apparatus was similar to the one described elsewhere. 18 Excitation was performed with a XeCl excimer Laser (Lambda Physics) at 308 nm. The light of a 100-W Xe lamp was crossed in 90°a ngle and detected with a photomultiplier (Hamamatsu) wired for high-speed response.…”