T. Nagahara et al., Naphthoylnaphthvalene -> naphthoylnaphthalene valence isomerization via anintermediate generated form the lowest excited singlet state, J PHOTOCH A, 124(1-2), 1999, pp. 47-52
Citations number
24
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
At room temperature, sub-picosecond laser photolysis of naphthoylnaphthvale
ne (NNV) and naphthoylnaphthalene (NN) reveals that their lowest excited si
nglet states ((NNV)-N-1* and (NN)-N-1*, respectively) have an identical Lif
etime (0.7 ps). In comparison with the results obtained by nanosecond laser
photolysis and steady-state photolysis of NNV (cf. Nakayama et al., Chem.
Phys. Lett. 266 (1997) 601), however, it is concluded that the decay channe
ls of (NNV)-N-1* are intersystem crossing to the lowest excited triplet sta
te and valence isomerization yielding ground-state NN; of course, the decay
channel of (NN)-N-1* is only intersystem crossing to the lowest excited tr
iplet state. Interestingly, steady-state photolysis of NNV at 77 K and then
measurements of the absorption and fluorescence spectra really indicate th
e existence of an intermediate (P-77) for (NNV)-N-1* --> NN valence isomeri
zation. Although no clear solvent effects on the absorption and fluorescenc
e spectra of P-77 are observed, it is proposed that P-77 is either a bond-c
loven species or a valence isomer of NNV generated from (NNV)-N-1*. (C) 199
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