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EFFECT OF DIELECTRIC CONSTANTS OF SOLVENTS ON THE BATHOCHROMIC SHIFTS IN RETINAL ISOMERS STUDIED THROUGH CARBON‐13 NMR AND CNDO/2 METHODS
Author(s) -
Sakurai Minoru,
Ando Isao,
Inoue Yoshio,
Chûjô Riichirô
Publication year - 1981
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1981.tb09011.x
Subject(s) - bathochromic shift , cndo/2 , chemistry , carbon 13 nmr , retinal , dielectric , computational chemistry , carbon fibers , photochemistry , organic chemistry , materials science , molecule , physics , optics , fluorescence , biochemistry , optoelectronics , composite number , composite material
— The carbon‐13 NMR and UV absorption spectra of all‐ trans ‐retinal have been obtained as a function of dielectric constant of solvent. The chemical shift data have been analyzed by the CNDO/2 MO calculation with the ‘solvaton’ model and Pople's theory for carbon‐13 shielding constant. It has been shown that the changes in chemical shifts are correlated with the electron densities on the corresponding carbon atoms. Considering this result, the ground state properties of all‐ trans ‐retinal have been discussed. An increase in the electronic charge alternation and a decrease in the bond alternation have been found along the polyene‐chain with an increase of dielectric constant. The electronic structure of 11‐ cis ‐retinal has been compared with that of all‐ trans ‐retinal in solution. It is suggested that the solvent‐induced red‐shift of absorption maxima is caused by the π‐electron derealization in the vicinity of the terminal oxygen atom. Finally, on the basis of these results, the environmental effect on the chromophore in rhodopsin has been discussed.