Features of self-organization of highly dilute solutions of (S)-, (R)-, and (SR)-methionines and related carbamides and glycolurils

Abstract

Aqueous solutions of (S)-, (R)-, and (SR)-methionines (1–3); carbamide (4); (S)-, (R)-, and (SR)-N-carbamoylmethionines (5–7); glycoluril (8); and glycolurils containing (S)and (R)-methionine moieties (9 and 10) kept under natural and hypoelectromagnetic conditions were studied in comparison by a complex of physicochemical methods (dynamic and electrophoretic light scattering, conductometry, pH-metry, and dielcometry). The process of selforganization and the properties of dilute solutions (1.0•10–15–10–1 mol L–1) of compounds 1–10 was shown for the first time to depend substantially on the structure of the solute and configuration of methionine (Met) enantiomers. In the series 1–3, the greatest ability to self-organization is observed for solutions of (SR)-Met in which supramolecular domains (1.0•10–5–1.0•10–1 mol L–1) and nanoassociates (1.0•10–11–1.0•10–8 mol L–1) are formed. The formation of nanoassociates in a concentration range of 1.0•10–12–1.0•10–6 mol L–1 can be responsible for the appearance of nonmonotonic concentration dependences of the physicochemical properties of solutions of N-carbamoylmethionines 5–7, whereas the physicochemical properties are more pronounced in solution of (S)-N-carbamoylmethionine 5 than in solutions of 6 and 7. The strongest influence of the configuration of the Met enantiomer on the ability of solution to self-organization was revealed in a series of glycolurils 9, 10: solutions of 9 with the (S)-Met moiety are disperse systems in which nanoassociates are formed in a range of 1.0•10–15–1.0•10–5 mol L–1, whereas in solutions of 10 with the (R)-Met fragment the ability to self-organization in the low-concentration range is absent.