Magnesium iodide–4,4′‐bipyridine–water (1/3/4) and strontium iodide–4,4′‐bipyridine–propan‐1‐ol (1/2.5/2)

Both of the title compounds, catena‐poly­[[[tetra­aqua­magnesium(I)]‐μ‐4,4′‐bi­pyridine‐κ²N:N′] diiodide bis(4,4′‐bi­pyridine) solvate], {[Mg(C₁₀H₈N₂)(H₂O)₄]I₂·2C₁₀H₈N₂}_n, (I), and catena‐poly­[[[μ‐4,4′‐bi­pyridine‐bis­[di­iodo­bis­(propan‐1‐ol)­strontium(I)]]‐di‐μ‐4,4′‐bi­pyridine‐κ⁴N:N′] bis(4,4′‐bi­pyri­dine) solvate], {[Sr₂I₄(C₁₀H₈N₂)₃(C₃H₈O)₄]·2C₁₀H₈N₂}_n, (II), are one‐dimensional polymers which are single‐ and double‐stranded, respectively, the metal atoms being linked by the 4,4′‐bi­pyridine moieties. The Mg complex, (I), is [cis‐{(H₂O)₄Mg(N‐4,4′‐bi­pyridine‐N′)_(2/2)}]_(∞|∞)I₂·4,4′‐bi­pyridine and Mg has a six‐coordinate quasi‐octahedral coordination environment. The Sr complex, (II), is isomorphous with its previously defined Ba counterpart [Kepert, Waters & White (1996). Aust. J. Chem. 49 , 117–135], being [(propan‐1‐ol)₂I₂Sr(N‐4,4′‐bi­pyridine‐N′)_(3/2)]_(∞|∞)·4,4′‐bi­pyridine, with the I atoms trans‐axial in a seven‐coordinate pentagonal–bipyramidal Sr environment.     

A three‐component cocrystal: benzoyl(hydroxyimino)acetonitrile–18‐crown‐6–water (2/1/4)

In the title compound, 2C₉H₆N₂O₂·C₁₂H₂₄O₆·4H₂O, the 18‐crown‐6 (1,4,7,10,13,16‐hexaoxacyclooctadecane) molecule resides across a centre of inversion. The adduct exists as a molecular hydrogen‐bonded complex featuring integration of two kinds of synthons, viz. [(18‐crown‐6)(H₂O)₄] [O...O = 2.8645 (18)–2.9014 (18) Å] and an oxime/aqua ensemble, PhC(O)C(CN)NOH...OH₂ [O...O = 2.5930 (18) Å]. The reliability of the oxime/aqua motif, sustained by the highly acidic cyanooxime, is an essential factor in the construction of multicomponent cocrystals and the accommodation of oxime species in macrocyclic hosts. The supramolecular structure is generated by the alternation of hydrophilic [(18‐crown‐6)(H₂O)₄] layers and bilayers of benzoyl(hydroxyimino)acetonitrile molecules, resulting in stacking interactions between the phenyl and cyano groups of 3.666 (2) Å.     

Ammonium hydrogen squarate–water (3/2)

In the title compound, NH₄⁺·C₄HO₄^?·H₂O, the hydrogen squarate anions and water molecules are arranged to form planes almost parallel to bc. The ammonium cations are located between these planes and cross‐link them in the a direction by means of an extensive network of hydrogen bonds. There are two symmetry‐independent sets of cations and anions. One of the hydrogen squarate anions and one of the ammonium cations are situated on a twofold axis and the H atoms of these moieties are disordered over the symmetry‐related sites.     

Leurosine me­thio­dide–methanol–water (1/3/2)

The crystal structure of a methanol–water solvate ofleurosine me­thio­dide, (leurosine‐CH₃)⁺I^?·3CH₃OH·2H₂O (C₄₇H₅₉IN₄O₉·3CH₃OH·2H₂O), is described. The piperidine ring of the upper part of the mol­ecule adopts a sofa conformation. An intramolecular hydrogen bond between the tertiary N and the hydroxyl group of the vindoline moiety of the mol­ecule is present.     

Intrinsic viscosities of sodium carboxymethylcellose in acetonitrile–water mixed solvent media using isoionic dilution method

Precise measurements on the viscosities of the solutions of sodium carboxymethylcellulose in water and in two acetonitrile–water mixtures containing 10 and 20 vol % of acetonitrile have been reported at 35, 40 and 50 °C. Isoionic dilutions were performed with the total ionic strengths of the solutions maintained with sodium chloride at ～4.20 × 10^?4 and 1.45 × 10^?3 mol dm^?3 of NaCl to obtain the intrinsic viscosities. The Huggins constants were also obtained from the experimental results. The influences of the medium, the temperature, and the total ionic strength on the intrinsic viscosities as well as on the Huggins constants have been interpreted from the points of view of the solvodynamic and thermodynamic interactions prevailing in the polyelectrolyte solution under investigation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1765–1770, 2007     

Density functional study of hydrogen‐bonded acetonitrile–water complex

We report the interaction of acetonitrile with one, two, and three water molecules using the Density Functional Theory method and the 6‐31+G* basis set. Different conformers were studied and the most stable conformer of acetonitrile–(water)_n complex has total energies –209.1922504, –285.6224478, and –362.068728 hartrees with one, two, and three water molecules, respectively. The corresponding binding energy for these three structures is 4.52, 8.34, and 22.48 kcal/mol. The hydrogen‐bonding results in blue, blue, and redshift in C?N stretching mode in acetonitrile with one, two, and three water molecules, respectively, whereas there was a redshift in O? H symmetric stretching mode of water. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

4‐Pyridone–terephthalic acid–water (2/1/2) and bis(3‐hydroxypyridinium) terephthalate

4‐Hydroxypyridine and terephthalic acid cocrystallize as a hydrate, 4‐pyridone–terephthalic acid–water (2/1/2), 2C₅H₅NO·C₈H₆O₄·2H₂O, from a methanol–water solution. The molecules form a two‐dimensional hydrogen‐bonded network resulting in sheets of hydrogen‐bonded molecules that lie parallel to the (10) plane. In contrast, 3‐hydroxypyridine and terephthalic acid form the salt bis(3‐hydroxypyridinium) terephthalate, 2C₅H₆NO⁺·C₈H₄O₄²⁻, giving rise to two‐dimensional hydrogen‐bonded sheets extending through the lattice parallel to the (10) plane.     

Crystal structure and hydrogen bonding in the hydrated cocrystalline salt tryptaminium–3,5‐dinitrobenzoate–quinoline–water (3/3/2/2)

The study of ternary systems is interesting because it introduces the concept of molecular preference/competition into the system where one molecule may be displaced because the association between the other two is significantly stronger. Current definitions of a tertiary system indicate that solvent molecules are excluded from the molecule count of the system and some of the latest definitions state that any molecule that is not a solid in the parent form at room temperature should also be excluded from the molecule count. In the structure of the quinoline adduct hydrate of tryptaminium 3,5‐dinitrobenzoate, 3C₁₀H₁₃N₂⁺·3C₇H₃N₂O₆⁻·2C₉H₇N·2H₂O, the asymmetric unit comprises multiple cation and anion species which are conformationally similar among each type set. In the crystal, a one‐dimensional hydrogen‐bonded supramolecular structure is generated through extensive intra‐ and inter‐unit aminium N—H…O and N—H…N, and water O—H…O hydrogen bonds. Within the central‐core hydrogen‐bonding associations, conjoined cyclic R₄⁴(10), R₅³(10) and R₄⁴(12) motifs are generated. The unit is expanded into a one‐dimensional column‐like polymer extending along [010]. Present also in the crystal packing of the structure are a total of 19 π–π interactions involving both cation, anion and quinoline species [ring‐centroid separation range = 3.395 (3)–3.797 (3) Å], as well as a number of weak C—H…O hydrogen‐bonding associations. The presence of the two water molecules in the crystal structure is considered to be the principal causative factor in the low symmetry of the asymmetric unit.     

Aqua­bis(3‐meth­oxy‐2‐pyridonato)­(2,2′:6′,2′′‐terpyridine)ruthenium(II)–acetonitrile–water (1/1/1)

The title compound, [Ru(C₆H₆NO₂)₂(C₁₅H₁₁N₃)(H₂O)]·CH₃CN·H₂O, is a transfer hydrogenation catalyst supported by nitro­gen‐donor ligands. This octa­hedral Ru^II complex features rare monodentate coordination of 3‐meth­oxy‐2‐pyridonate ligands and inter­ligand S(6)S(6) hydrogen bonding. Comparison of the title complex with a structural analog with unsubstituted 2‐pyridonate ligands reveals subtle differences in the orientation of the ligand planes.