SOME PHOTOPHYSICAL PROPERTIES OF 3‐CARBETHOXYPSORALEN, 8‐METHOXYPSORALEN and 5‐METHOXYPSORALEN TRIPLET STATES

Abstract

Triplet absorption spectra. extinction coefficients (e., ), decay rates ( k , ) . oxygen quenching rates (kcl) and intersystem crossing yields (Q ,) for 3-carbethoxypsoralen (3-CPs). X-methoxypsoralcn (%MOP) and 5-methoxypsoralen (5-MOP) in methanol are reportcd. For 8-MOP and 3-CPs corresponding values are also reported with water as the solvent. Some photophysical data are also reported for 5-MOP in water, but E , and Q I were not obtained.The phosphorescence spectra for these furocoumarin derivatives in ethanol at 77 K are reported together with the corresponding lowest triplet energy and lifetime. The values 0 1 the various photophysical properties obtained are compared with values reported by prcviouh workers.

Luminescence characteristics of new substituted coumarins

“…Unfortunately, the phosphorescence lifetimes in deoxygenated solutions have not been reported. However, the phosphorescence lifetime of 8-MOP obtained by us (0.55 sec) agrees with that reported for oxygen-containing solutions [23] where the phosphorescence lifetime of 8-MOP in ethanol is ≈0.65 sec. The phosphorescence lifetime of 8-MOP in ethanol was reported as ≈0.72 sec [6].…”

Photoinduced Electron Transfer between Psoralens and DNA: Influence of DNA Sequence and Substitution

“…Yet, the maximum of the triplet absorption around 350 nm is discernible at the largest delay times and in the offset spectrum of a global fit (Figure S6). Triplet state yields of 0.06 or 0.14 can be found in the literature . Our data point towards the lower value.…”

“…Triplet state yields of 0.06 or 0.14 can be found in the literature. [31,33] Our data point towardst he lower value. Apart from that, the offset spectrum of the globalf it reveals ar elatively large amount of solvated electron absorption.…”

Singlet Oxygen Generation by Furocoumarin Triplet States—i. Linear Furocoumarins (Psoralens)

“…The pulse radiolysis system for determination of AcT values was as described previously (Keene, 1964) but data analysis has been upgraded from a photographic technique to the use of a Tektronix 7612D digitiser interfaced with a Hewlett-Packard 98368 computer. The AcT values were determined via the energy-transfer technique using biphenyl triplet in benzene as standard (Bensasson et al, 1983).…”