The Optical Rotatory Dispersion and Circular Dichroism of Aromatic Amino Acids

The CD and ORD of d-phenylglycine and l-phenylalanine were measured at various pH’s. The superficial small pH dependence of the CD maximum around 220 mμ and the anomalous large [θ] value at the CD maximum in both aromatic amino acids suggest an interaction between the 1La transition of the benzene ring and the n→π* transition of the carboxyl group. The ORD and CD of l-α-amino-β-benzalpropionic acid, l-α-amino-β-benzylpropionic acid, and l-2-amino-4-phenyl-butanol-1 were also measured, and the screening effect of the methylene groups which exist between a benzene ring and an asymmetric carbon atom was discussed.