Optical Activity of Crystalline Glutamic Acids

Abstract

As the first study on gyro-optical properties of amino acids, temperature dependences of the gyration tensor components of l- and d-glutamic acids were measured by using the HAUP (high-accuracy universal polarimeter). It was confirmed that the corresponding tensor components of the two enantiomers are the same in magnitude but opposite in sign. It is proposed that r = (ρ0C − ρ0S)/ρ0C be defined as the `chirality index', where ρ0c and ρ0s designate rotatory powers per molecule in a crystal and in a dissolved state in liquid, respectively. It represents a measure of structural contribution of optical activity (OA) in a crystal. This value is 0.992 in glutamic acids.