Enantioselective Crystallization of Chiral Inorganic Crystals of ϵ‐Zn(OH)₂ with Amino Acids

Abstract

Many inorganic materials can form crystals, but little is known about their enantioselective crystallization. Herein, we report on the enantioselective crystallization of ϵ‐Zn(OH)2 (Wulfingite) chiral crystals by using amino acids. Crystals of ϵ‐Zn(OH)2 were crystallized from supersaturated sodium hydroxide and zinc nitrate aqueous solutions in the presence of l‐ or d‐arginine. All of the chiral measurements, such as selective chiral adsorption by circular dichroism (CD), chiral chromatography, and polarimetry measurements, clearly show chiral discrimination during the crystallization of ϵ‐Zn(OH)2. In addition, a new method has been developed for identifying chirality in crystals by using electron paramagnetic resonance (EPR). Although the values of chiral induction of the ϵ‐Zn(OH)2 crystals obtained are somewhat low, these values are still significant because they demonstrate that enantioselectivity during the crystallization of chiral inorganic crystals with chiral additives can be achieved. The method can be applied to many chiral inorganic systems. Understanding and controlling the crystallization of chiral inorganic crystals is important for gaining knowledge on the interaction of chiral molecules with inorganic surfaces. This knowledge can lead to an understanding of basic scientific questions such as the evolution of homochirality in biomolecules and the development of chiral inorganic crystals for a variety of purposes such as asymmetric catalysis and optical applications.

Chiral nanocrystals grown from MoS2 nanosheets enable photothermally modulated enantioselective release of antimicrobial drugs

“…Transferring chirality or handedness from light and enantiomeric molecules to synthetic materials, e. g. semiconductors, plasmonics, and tellurium nanocrystals, brings new life to nanotechnology in significant systems 1 – 4 , enhances our understanding of biological and biomimetic processes and enables the development of practical applications 5 – 7 . Currently, large-scale and straightforward synthetic methods for nanosized chiral morphologies are still being developed 8 . Chiral nanostructures have stereochemical structures and likewise unique intrinsic properties, and remarkable effort has been expanded to study their functions and characteristics 9 – 11 .…”

Possible chemical and physical scenarios towards biological homochirality

“…The claimed specific adsorptions for racemic mixtures of amino acids likely originated from the different purities between (S)-and (R)-amino acids; or contaminants of biological origin such as microbial spores. 279 Such issues are not old-fashioned and despite great improvement in analytical and purification techniques, the difference in enantiomer purities is most likely at the origin of the different behaviour of amino acid enantiomers observed in the crystallization of wulfingite (e-Zn(OH) 2 ) 280 and CaCO 3 281,282 in two recent reports.…”

Chirality communications between inorganic and organic compounds

“…For example, ε-Zn(OH) 2 (Wulfingite) chiral crystals showed enantioselective adsorption of Arginine. 99 The surfaces of metals are easier to deal with as compared to minerals. Thus, chiral metal surfaces have been more explored.…”