Chiral crystallization of glutamic acid on self assembled films of cysteine

Abstract

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.

Amino‐Acid‐Based Chiral Nanoparticles for Enantioselective Crystallization

“…Our basic hypothesis is that the chiral polymeric nanoparticles will act as selective chiral nuclei and lead to enantioselective crystallization of one enantiomer onto the polymeric nanoparticles. The assumption is supported by previous research on the enantioselective crystallization of l ‐glutamic acid on chiral self‐assembled multilayers surfaces . We studied the enantioselective crystallization of amino acids because they are the basis of all life processes and crystallization is one of the key steps in their preparation.…”

Neuronal Growth on l- and d-Cysteine Self-Assembled Monolayers Reveals Neuronal Chiral Sensitivity

“…The stability of the SAM surfaces was previously detected, presenting high and long-term chemical stability for the duration of the experiments. 3 Cell Culture. Culturing method has been previously described; 46 briefly, neurons were isolated from the CNS of adult medicinal leeches Hirudo medicinalis.…”

Chiral Self Assembled Monolayers as Resolving Auxiliaries in the Crystallization of Valine

“…After removal from solution, the substrates were rinsed with copious amounts of deionized water and blow dried with nitrogen. Self assembled monolayers of cysteine on gold have been previously studied using X‐ray photoelectron spectroscopy (XPS) and Scanning Tunneling Microscopy (STM) 14, 18. It has been reported that cysteine molecules are absorbed onto gold through the sulfur atom, while leaving the other two groups (COOH and NH 2 ) free.…”

“…Naturally chiral bulk crystalline surfaces have been shown to display chiral selectivity when immersed in a racemic solution 13. Self‐assembled monolayers of (+)‐ L and (−)‐ D cysteine on gold substrates were used as resolving auxiliaries in the crystallization of rac‐glutamic acid (a conglomerate) and rac‐histidine (a racemic compound) 14, 15. Similarly, chiral discrimination between ( R )‐ and ( S )‐thalidomide enantiomers was achieved using SAMs of ( R )‐ and ( S )‐1,1′‐binaphthalene‐2, 2′‐dithiol (BNSH) 16.…”