Mechanism of chiral recognition by enantiomorphous cytosine crystals during enantiomer adsorption

Abstract

The search for the sources of Life chirality is far from successful. In the terrestrial theory of the chirality emergence in living matter, one of the main possible mechanisms is...

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.…”

“…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…”

“…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.…”

“…The adsorption procedure and chromatographic control conditions were identical to those described in our previous work. 23 In gas chromatography, the crystals in the column were preliminarily conditioned for 10 hours at a maximum operating temperature of 120 °C. Such a temperature was sufficient for the decomposition of hydrates, so in the case of phloroglucinol crystals, obtained both from ethanol and water, only phloroglucinol and not phloroglucinol dehydrate crystals were in the column.…”

“…However, if crystallization is conducted in aqueous solutions, phloroglucinol dihydrate crystallizes, which belongs to the Pnma achiral space group. 25 To prove the chirality of the crystals, we have employed the same approach outlined in our previous article: 23 Two sets of crystals were obtained, one certainly chiral and the other certainly achiral. These two sets were crystallized using a similar technique, the only difference being the solvent used.…”