Hydrogen-bonding patterns in 5-fluorocytosine–melamine co-crystal (4/1)
The asymmetric unit of the title compound comprises two independent 5-fluorocytosine molecules and one half-molecule of melamine. The 5-fluorocytosine molecules are linked through two different homosynthons; one is formed via a pair of N—H⋯O hydrogen bonds and the second via a pair of N—H⋯N hydrogen bonds. The 5-fluorocytosine and melamine molecules interact via N—H⋯O, N—H⋯N and N—H⋯O, N—H⋯N, C—H⋯F hydrogen bonds.
Melaminium glutarate monohydrate.
The crystal structure of the title new melaminium salt, 2,4,6-triamino-1,3,5-triazin-1-ium glutarate monohydrate, C(3)H(7)N(6)(+) x C(5)H(7)O(4)(-) x H(2)O, is built up from singly protonated melaminium residues, mono-dissociated glutarate ions and water molecules. The melaminium residues are interconnected by four N[bond]H...N hydrogen bonds to form chains. These chains of melaminium residues form a stacking structure. The glutarate anions form a hydrogen-bonded zigzag polymer of the form [...HOOC(CH(2))(3)COO...HOOC(CH(2))(3)COO...](n). The oppositely charged moieties, i.e. the melaminium and glutarate chains, form two-dimensional polymeric sheets. These sheets are interconnected by O[bond]H...O hydrogen bonds between the COO(-) moieties and the water molecules, and these hydrogen bonds stabilize the stacking structure.
The Russian language maintenance and language contacts
In our introductory article, we outline the main sociolinguistic features of Russian as a heritage language of post-Soviet immigrants in European settings and beyond. We offer a general overview of the evolution of Russian as a global language, with a particular focus on its geodemographics and economic and social value as a lingua franca . Based on this, we analyse the main principles defining the maintenance of Russian as a language of migration and as a heritage language in different countries, and emphasise the most important questions that still need to be addressed in this field of research. The main objective of this special issue is to combine the most recent research on the vitality of different languages of post-Soviet republics in new political milieu, with a particular focus on European and Asian countries, but there are other objectives as well. We propose to explore the factors that have either favoured or hindered the maintenance and transmission of languages of post-Soviet immigrants and repatriates, and how these sociolinguistic processes become evident in language vitality on both private and public levels. Our special issue primarily addresses the questions of family language policy, new language contacts and their management, and linguistic landscape in heritage speakers, diasporas and their new settings in Europe, Asia and the US.