Preferential intermolecular interactions in a racemic mixture of amino acid Schiff base, conformational structures in solid state, and DFT studies

Abstract

In the present work, we report the green synthesis of a Shiff base [N-(2-hydroxy-1-naphthylidene)-L-phenylalanine (1)] derived from an α-amino acid through an ultrasound-assisted synthesis method with excellent chemical yield in a short period of time. In the crystal framework, we found that compound 1 goes through a racemization process and remarkably a preferential intermolecular interaction between amino acid molecules with the same configuration was observed, i.e., a homo enantiomeric preference (HEP). This could indicate that an enantiomeric recognition could be observed in racemic mixtures of compounds that are derived from α-amino acids. Besides, a conformational study of 1 and a polymorph previously obtained in solid state for the same molecule was extensively discussed by the Hirshfeld surface, Finger plots, and DFT calculations.