Search

In the course of a study on artificial sweeteners, new crystal structures of cyclamic acid, sodium cyclamate, potassium cyclamate, ammonium cyclamate, rubidium cyclamate and tetra- n-propylammonium cyclamate have been determined. Cyclamic acid exists in its zwitterionic form in the crystalline state. The zwitterions are connected through hydrogen bonds of the N—H...O type to form two-dimensional sheets. The sodium, potassium, ammonium and rubidium cyclamates are isostructural, with the cyclamate moieties linked through hydrogen bonds into linear chains. Taking into account the connectivity through cations, two-dimensional layers with a hydrophobic surface are constructed. In tetra( n-propyl)ammonium cyclamate the large, non-coordinating cation apparently prevents the formation of chains and thereby facilitates the centrosymmetric head-to-head discrete dimeric arrangement of the cyclamate moieties. [ABSTRACT FROM AUTHOR]

The crystal structures of two monomeric copper(II) carboxylates with 2-aminopyridine have been determined by X-ray diffraction. The hexanoate complex crystallizes as its acetonitrile solvate [Cu(C[sub 6]H[sub 11]O[sub 2])[sub 2](C[sub 5]H[sub 6]N[sub 2])[sub 2]·CH[sub 3]CN] in the triclinic space group P-1 with a = 8.1020(6), b = 13.7106(9), c = 13.7673(9) Å, α = 113.79(1), β = 103.86(1), and γ = 94.38(4). The heptanoate compound shows an unsolvated structure [Cu(C[sub 7]H[sub 13]O[sub 2])[sub 2](C[sub 5]H[sub 6]N[sub 2])[sub 2]] and also crystallizes in the triclinic space group P-1 with the following cell parameters: a = 8.4487(9), b = 12.238(1), c = 13.504(2) Å, α = 87.034(9), β = 77.489(9), and γ = 71.41(1)°. Both compounds contain the CuO[sub 4]N[sub 2] chromophore, with ligands arranged around the copper center in a cis mode. 2-Aminopyridine is coordinated through the endocyclic nitrogen atom. The ortho position of the amino group, with respect to the pyridine nitrogen atom, allows the formation of both, intra- and intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

The article discusses a research study on the interaction of pharmaceutical agent fluconazole with salicylic acid in a 1:1 ratio. Researchers dissolved equimolar amounts of salicylic acid and fluconazole in acetonitrile at 323 degrees Kelvin (K) and gained colourless crystals for analysis. Results showed that molecules of salicylic acid and fluconazole formed homomeric centrosymmetric dimers through hydrogen bonds.