Excitation Energy Dependence of Transient Absorptions of [N,N′-o-Phenylenebis(salicylideneaminato)]cobalt(II) in Dmf Solution

Abstract [N,N′-o-Phenylenebis(salicylideneaminato)]cobalt(II), [Co(saloph)], forms two solvated complexes in the dmf solution; that is [Co(saloph)]·dmf at higher temperature and [Co(saloph)]·2dmf at lower temperature. The transient absorptions of the two species were measured in the present work with irradiation of the 532 nm- and 355 nm-light. For [Co(saloph)]·2dmf, the intensity change of the transient absorption induced by the 532 nm-excitation was ca. 5 times larger than that induced by the 355 nm-excitation, although the spectra was the same. By contrast, for the transient absorption of [Co(saloph)]·dmf, no dependence on the excitation wavelength was found with respect to the spectra, the absorption intensity or the decay rates. A quantum calculation of the electronic excited states was carried out by ZINDO model. Taking into consideration the calculated results, the observed differences between the excitation-wavelength dependence of the transient absorptions are discussed.