利用L-半胱氨酸自组装膜和混合溶剂协同作用手性拆分DL-谷氨酸

Co-effect of L-Cysteine Self-assembled Monolayers and Mixed Solvents on Chiral Separation of DL-glutamic Acid

基于L-半胱氨酸(L-Cys)自组装膜(SAMs)在乙醇-水混合溶剂体系中对外消旋谷氨酸展现出的手性识别能力,在含60%(体积分数)乙醇的乙醇-水混合溶剂中,利用L-Cys SAMs对不同手性谷氨酸的选择性结晶作用,通过多次重结晶,分离出纯D-谷氨酸晶体,从而实现了对DL-谷氨酸的手性拆分.

In general, crystallization of a racemic glutamic acid aqueous solution will yield optically inactive raeemic compound crystals（DL-erystals）, it makes a great challenge to chiral separation of DL-glutamic acid. We found that D-crystals and L-crystals （ the conglomerates） of glutamic acid can be deposited from the mixed solvents of water and ethanol, providing an opportunity to separate the D- and L-forms of glutamic acid. Moreover, L-cysteine self-assembled monolayers （L-Cys SAMs ） on the gold （111） surface showed chiral discriminating ability in the mixed solvents. SEM, XRD and Raman techniques were employed to characterize the crystals grown on the L-Cys SAMs. The relative contents of L-forms and D-forms in the conglomerates were measured by a pre-column derivatization HPLC method. The experimental results demonstrated that the conglomerates with D-glutamic acid excess were obtained on the L-Cys SAMs from a 60% （volume fraction） ethanol-water mixed solvent. And more importantly, the pure D-crystals alone can be deposited from the mixed solvents by the co-effect of L-Cys SAMs and mixed solvents and a typical ＂in-series enriched method＂.