Chiral crystallization of glutamic acid on self assembled films of cysteine.

In this article, we describe the preparation and use of chiral surfaces derived from enantiomerically pure crystals of amino acids. For this purpose, we chose to employ a self-assembly process to grow nanoscale chiral films of (+)-L or (-)-D cysteine, onto gold surfaces. We utilized those chiral films as resolving auxiliaries in the crystallization of enantiomers from solutions. To demonstrate the chiral discriminating ability of the chiral surfaces in crystallization processes, we investigated the crystallization of rac-glutamic acid onto the chiral films. Our study demonstrates the potential application of chiral films to control chirality throughout crystallization, where one enantiomer crystallizes on the chiral surfaces with relatively high enantiomeric excess. In addition, crystallization of pure glutamic acid enantiomers, and its racemic compound on to chiral films resulted in crystal morphology modification with preferred crystal orientation, which assists in the interpretation of the ability of our chiral surfaces to function as chiral selectors.