Supramolecular chiral surface of nickel sulfate hexahydrate crystals and its ability to chirally recognize enantiomers by adsorption data

Abstract

The chiral recognition ability of the surface of α-NiSO4·6H2O was found using gas and liquid chromatography.

Possibility of chiral recognition by adsorption on enantiomorphous crystals: the impact of crystal surface polarity

“…This means that the formation of the layers of limonene enantiomers was different. This corresponds to the results of adsorption isotherm analysis on cytosine 23 and nickel sulfate hexahydrate, 24 in which enantiomorphic crystals do not recognise individual molecules of enantiomers, but a layer of enantiomers on their surface. Since limonene–limonene interactions were stronger than limonene–crystal surface interactions, the formation of a second layer may begin before the crystal surface was covered by the first layer.…”

“…Thus, the maximum difference in adsorption values was 3.5%. In general, the enantioselectivity provided by porous polymers modified with hippuric acid and phloroglucinol is lower than that of previously studied samples modified with nickel sulfate hexahydrate 24 and cytosine. 23 The isotherms also differed in their shape, as shown in Fig.…”

“…It was found in our previous studies that the adsorption of some enantiomers on cytosine 23 and retgersite 24 crystals, obtained under Viedma ripening conditions, only significantly differs over a certain range of surface coverages, at which the concentration of adsorbed molecules is high enough to ensure lateral enantiomer–enantiomer interactions on the crystal surface.…”

Chiral recognition during adsorption on MOF [{Cu12I(trz)8}·4 Cl·8 H2O]n, obtained from achiral building blocks without an external source of chirality

“…This differed from the previously studied nonporous chiral crystals. 7,8,10 For such crystals the enantiomer isotherms differed only in the nonlinear region. This was caused by the mandatory formation of an adsorption layer on the adsorbent surface for supramolecular chiral recognition.…”

“…A different adsorption of enantiomers was found on crystals with a supramolecular chiral surface, obtained from achiral precursors. 7–10 Examples of enantiomorphic crystals are retgersite, cytosine, hippuric acid, phloroglucinol, CsCuCl 3 , γ-glycine, and others. 11–14 It was found that the recognition of enantiomers by the supramolecular chiral surface of non-porous crystals is observed only in the region of high surface coverage.…”