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

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