Schiff bases electronic spectra

Miscellaneous Physical Chemistry. A kinetic study has been made of the electrochemical reduction of /8-carotene. The photoelectron quantum yield spectrum and photoelectron microscopy of /3-carotene have been described. Second-order rate constants for electron-transfer reactions of radical cations and anions of six carotenoids have been determined. Electronic energy transfer from O2 to carotenoids, e.g. canthaxanthin [/8,/3-carotene-4,4 -dione (192)], has been demonstrated. Several aspects of the physical chemistry of retinal and related compounds have been reported, including studies of electrochemical reduction, the properties of symmetric and asymmetric retinal bilayers, retinal as a source of 02, and the fluorescence lifetimes of retinal. Calculations have been made of photoisomerization quantum yields for 11-cis-retinal and analogues and of the conversion of even-7r-orbital into odd-TT-orbital systems related to retinylidene Schiff bases. ... 

A UV-Vis absorption spectrum of this branched molecule showed that it is transparent in the visible range, an important criterion for application as a TPA material. Unfortunately, however, the Schiff bases of centrosymmetric ii-systems—in contrast to the imines of noncentrosymmetric ones—are hydrolytically quite instable, and thns they are not suitable for applications as nonlinear optical materials. The difference in chonical stability might lie in the possibility of electron transfer and hence stabilization by conjugation of Ji-electrons in noncentrosymmetric dodecaborate derivatives (Bernard et al., 2006). 

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