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 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. In this 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.