Models for Visual Pigments. The Effect of the Imidazolyl Group on the Absorption Maxima of the Retinal Schiff Base

Article abstract of DOI:10.1246/bcsj.54.1101

The title effect has been investigated with the imidazolyl group either externally added or intramolecularly combined.N-Retinylidenebutylamine was protonated with imidazole derivatives under neutral conditions and was absorbed at longer wavelengths compared with carboxylic acids.The absorption peak with the imidazolyl group intramolecularly combined was highly affected by the structure, protonated N^α-retinylidene-L-histidine octadecylamide having an absorption maximum at 494 nm caused by the inductive effect and the polar imidazolyl group.