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Studies of the triplet state properties of hypocrellin A by nanosecond flash photolysis

1994; Elsevier BV; Volume: 78; Issue: 3 Linguagem: Inglês

10.1016/1010-6030(93)03727-x

1873-2666

Hu Yizhen, Jing‐Yi An, Qin Li, Lijin Jiang,

Porphyrin and Phthalocyanine Chemistry

Hypocrellin A (HA) is an efficient phototherapeutic agent. Its triplet properties have been investigated in cyclohexane using the nanosecond flash photolysis technique. The triplet—triplet (T—T) absorption spectrum of HA gives three bands with absorption maxima at around 520, 555 and 600 nm. The triplet energy level for HA has been estimated to be about 42.5 kcal mol−1 by the energy transfer method. The extinction coefficients for the T—T absorption of HA have been determined by the ground state depletion method. The triplet quantum yield of HA is 0.78±0.04 (by reference to benzophenone).