The reaction of barium(II) hydroxide with 2-furoic acid (pyromucic acid, Hfur) gave 1D coordination polymer {[Ba₃(fur)₆(Hfur)₂(H₂O)₈]}_n·4nH₂O (I). According to X-ray diffraction data, I contains two symmetrically independent barium cations, which have different environments: Ba(1) coordinates six fur^– anions, while Ba(2) is a fragment of heteroleptic coordination (fur^–, Hfur, and H₂O) (CIF file CCDC no. 2063380). The supramolecular polymeric architecture of I is determined by bridging water molecules and numerous hydrogen bonds between coordinated and solvation water molecules to form a 1D motif. The arrangement of Ba²⁺ ions in the trinuclear moiety {Ba₃(fur)₆(Hfur)₂(H₂O)₈} of the polymer is nearly linear. The thermal behavior of I, investigated by simultaneous thermal analysis (argon atmosphere), showed a stepwise character of thermal decomposition caused by gradual destruction of the hydrogen-bonded framework and the subsequent partial destruction of the organic part. Analysis of the biological activity of I against the non-pathogenic Mycolicibacterium smegmatis strain showed low sensitivity of the bacterial wall to the complex.

Although the most promising applications of ionogels require their contact with aqueous media, few data are available on the stability of ionogels upon exposure to water. In this paper, a simple, easy-to-setup and precise method is presented, which was developed based on the continuous conductivity measurements of an aqueous phase, to study the washout of imidazolium ionic liquids (IL) from various silica-based ionogels immersed in water. The accuracy of the method was verified using HPLC, its reproducibility was confirmed, and its systematic errors were estimated. The experimental data show the rapid and almost complete (>90% in 5 h) washout of the hydrophilic IL (1-butyl-3-methylimidazolium dicyanamide) from the TMOS-derived silica ionogel. To lower the rate and degree of washout, several approaches were analysed, including decreasing IL content in ionogels, using ionogels in a monolithic form instead of a powder, constructing ionogels by gelation of silica in an ionic liquid, ageing ionogels after sol–gel synthesis and constructing ionogels from both hydrophobic IL and hydrophobic silica. All these approaches inhibited IL washout; the lowest level of washout achieved was ~14% in 24 h. Insights into the ionogels’ structure and composition, using complementary methods (XRD, TGA, FTIR, SEM, NMR and nitrogen adsorption), revealed the washout mechanism, which was shown to be governed by three main processes: the diffusion of (1) IL and (2) water, and (3) IL dissolution in water. Washout was shown to follow pseudo-second-order kinetics, with the kinetic constants being in the range of 0.007–0.154 mol⁻¹·s⁻¹.

The ionic compound [Co(OC₅H₂N(NO₂)₂)₄]((C₂H₅)₃NH)₂ (I) was synthesized by the reaction of CoCl₂·6H₂O with 2-hydroxy-3,5-dinitropyridine in acetonitrile in the presence of triethylamine as a deprotonating agent. The structure of compound I was studied by X-ray diffraction (CCDC no. 2196071) and thermodynamic characteristics of I were determined.

A new binuclear "paddle-wheel" complex, [Co₂(bhbz)₄(EtOH)₂]·4EtOH (1, Hbhbz-3,5-di(tert-butyl)-4-hydroxybenzoic acid); an isostructural zinc complex (2); a and magnetically diluted sample of [Zn_1.93Co_0.07(bhbz)₄(EtOH)₂]·4EtOH (3) were obtained. Molecular structures of 1 and 2 were determined by single-crystal X-ray diffraction. DFT calculations for 1 indicate strong Co-Co antiferromagnetic exchange interactions in the binuclear fragment. It was shown that when one paramagnetic ion in the binuclear molecule is replaced by a diamagnetic zinc(II) ion, the remaining cobalt(II) ion can be considered as an isolated center with magnetic anisotropy, the parameters of which are determined by ab initio calculations. Magnetic properties for samples 1 and 3 were investigated and analyzed in detail.

The interaction of Mg²⁺ with 2-furoic acid (HFur) and oligopyridines, depending on the synthesis conditions, leads to the formation of mixed-ligand complexes [Mg(H₂O)₄(phen)]·2HFur·phen·H₂O (1), [Mg(NO₃)₂(phen)₂] (2) and [Mg₃(Fur)₆(bpy)₂]·3CH₃CN (3); these structures were determined with an SC X-ray analysis. According to the X-ray diffraction data, in complex 1, obtained in ambient conditions, the magnesium cation coordinated four water molecules and one phenanthroline fragment, while in complexes 2 and 3 (synthesized in an inert atmosphere), the ligand environment of the complexing agent was represented by neutral oligopyridine molecules and acid anions. The thermal behavior of 1 and 2 was studied using a simultaneous thermal analysis (STA). The in vitro biological activity of complexes 1–3 was studied in relation to the non-pathogenic Mycolicibacterium smegmatis and the virulent strain Mycobacterium tuberculosis H₃₇Rv.