Spectral and photophysical behavior of 2,4,6,8,10-dodecapentaenal and schiff base: evidence for a low-lying singlet excited state of forbidden character

THE VISUAL PROCESS: PHOTOPHYSICS and PHOTOISOMERIZATION OF MODEL VISUAL PIGMENTS and THE PRIMARY REACTION

“…An extensive series of polyenals and polyenones have been investigated including retinal homologues of considerably shorter and longer chain length than retinal , as well as series of linear polyenals of the type CH,-(CH=CIJ),,-CHO (Das and Becker, 1982;Becker et al, 1979). More than twenty polyene aldehydes and ketones of sev-eral geometric types were investigated in the retinal homologue study and five for the linear polyene aldehydes (n = 5).…”

“…Also the natural fluorescence lifetimes of the all-trans SB in alkane solvents and the 9-cis SB (Becker et al, 1976), compared to that predicted from absorption data gave clear indication that the lowest state of these SB was 'Ag-'. Moreover, based on absorption spectral studies of two different series of polyene Schiff bases at 295 K and 77 K, where retinal SB homologs from two to eight double bonds and a 2,4,6,8,10-dodecapentaenal SB were involved, it is clear that the '(n,T*) state has moved to significantly higher energy (some 200Cb5000 cm-') in the Schiff bases compared to the aldehydesipolyenals Becker et al, 1979). This then makes the ' A g -~ state not only the lowest ' ( T , T :~) state but clearly the lowest state of any configuration.…”

“…Triplet state quantum yields (@,) of retinals are particularly solvent sensitive (Fischer and Weiss, 1974;Das and Hug, 1982;Das and Becker, 1979;Bensasson et al, 1983;Veyret et al, 1978). Recall that is variable particularly in the presence of polar hydrogen bonding solvents compared to hydrocarbons.…”

“…The same is generally true for all other retinals. Based on these results and others it was decided that very likely a state order change occurred for the lowest excited state going from a hydrocarbon to a polar solvent, particularly when hydrogen bonding (Das and Becker, 1979;Becker et al, 1978 where the location of the 3(n,n'') in hydrogen bonding case is uncertain):…”

Polarisations-Uv-Absorptionsspektroskopische Und Kristallographische Untersuchung Der Kristalle Von All-Trans Und 11-Cis Retinal

“…Ferner wurden von Birge et al (1978Birge et al ( und 1982b zwei-Photonenspektroskopische Untersuchungen durchgeführt. Darüber hinaus sind von Christensen und Kohler (1975), Becker et al (1979) und Hudson und Loda (1981) Anregungs-und Emissionsuntersuchunqen in n-Alkan Matrizen bei 77K und 4K durchgeführt worden. Sperling,1973).…”