Syntheses and crystal structures of three salts of sparfloxacin, one incorporating extended tapes of fused penta­gonal water assemblies

Three organic salts of sparfloxacin, a difluorinated third-generation fluoro­quinolone anti­biotic, have been synthesized and their crystal structures determined. The salts, sparfloxacinium 4-nitro­benzoate dihydrate, C19H23F2N4O3+·C7H4NO4−·2H2O (I), sparfloxacinium 2-phenyl­acetate, C19H23F2N4O3+·C8H7O2− (II), and sparfloxacinium 4-methyl­benzoate trihydrate, C19H23F2N4O3+·C8H7O2−·3H2O (III), exhibit similar inter-species packing inter­actions. The overall crystal structures each, however, have their own distinct characteristics, which are described here along with a Hirshfeld surface analysis of the various atom–atom contacts involving the sparfloxacinium cations. In the crystal structure of III, an extended supra­molecular tape of edge-fused hydrogen-bonded water penta­gons was found. These penta­gonal water and tape motifs are compared to related constructs in a broad selection of structure types, ranging from macromolecules to small mol­ecules, clathrates, and exotic `ice' formations on clean metal surfaces

Syntheses and crystal structures of 4-(4-methoxyphenyl) piperazin-1-ium 4-methylbenzoate monohydrate and bis[4-(4-methoxyphenyl)piperazin-1- ium] benzene-1,2-dicarboxylate

Co-crystallization of N-(4-meth­oxy­phen­yl)piperazine with 4-methyl­benzoic acid and with benzene-1,2-di­carb­oxy­lic acid yields the salts 4-(4-meth­oxy­phen­yl)piperazin-1-ium 4-methyl­benzoate monohydrate, C11H17N2O+·C8H7O2−·H2O (I), and bis­[4-(4-meth­oxy­phen­yl)piperazin-1-ium] benzene-1,2-di­carboxyl­ate, 2C11H17N2O+·C8H4O42− (II). These salts both crystallize with Z′ = 2, in space groups P[\overline{1}] and Pna21, respectively. In compound (I), a combination of four O—H⋯O, four N—H⋯O, one C—H⋯O and one C—H⋯π(arene) hydrogen bonds link the six independent components into complex sheets, within which the two piperazine rings, the two anions, and the two water mol­ecules are related by an approximate, non-crystallographic translation along the b-axis direction. In compound (II), sheets containing R44(18) and R1012(38) rings are formed by the combined action of eight independent N—H⋯O hydrogen bonds. Comparisons are made with the structures of some related compounds

Syntheses and crystal structures of 4-(4-nitro­phen­yl)piperazin-1-ium benzoate monohydrate and 4-(4-nitro­phen­yl)piperazin-1-ium 2-carb­­oxy-4,6-di­nitro­phenolate

Crystal structures are reported for two mol­ecular salts containing the 4-(4-nitro­phen­yl)piperazin-1-ium cation. Co-crystallization from methanol/ethyl acetate solution of N-(4-nitro­phen­yl)piperazine with benzoic acid gives the benzoate salt, which crystallizes as a monohydrate, C10H14N3O2·C7H5O2·H2O, (I), and similar co-crystallization with 3,5-di­nitro­salicylic acid yields the 2-carb­oxy-4,6-di­nitro­phenolate salt, C10H14N3O2·C7H3N2O7, (II). In the structure of (I), a combination of O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds links the components into sheets, while in the structure of (II), the supra­molecular assembly, generated by hydrogen bonds of the same types as in (I), is three dimensional. Comparisons are made with the structures of some related compounds

Synthesis and crystal structures of 1-benzoyl-4-(4-nitro­phen­yl)piperazine and 1-(4-bromo­benzo­yl)-4-phenyl­piperazine at 90 K

Synthesis and crystal structures of 1-benzoyl-4-(4-nitro­phen­yl)piperazine, C17H17N3O3, (I) and 1-(4-bromo­benzo­yl)-4-phenyl­piperazine, C17H17BrN2O, (II) are described. Compounds I and II crystallize in the ortho­rhom­bic and monoclinic crystal systems with space groups Pna21 (Z′ = 2, I) and P21 (Z′ = 1, II), respectively. The crystal of II was a two-component aggregate, treated as a `twin' for data-acquisition purposes. There are no conventional hydrogen bonds in either I or II, but there are weaker C—H⋯O contacts. Each mol­ecule consists of a central piperazine ring in a chair conformation, with either benzoyl and nitro­phenyl (I) or 4-bromo­benzoyl and phenyl (II) groups attached to different nitro­gen atoms of the piperazine. The various atom–atom contact coverages as qu­anti­fied by Hirshfeld surface analysis fingerprint plots are given

Syntheses, crystal structures and Hirshfeld surface analysis of 4-(4-nitro­phen­yl)piperazin-1-ium tri­fluoro­acetate and 4-(4-nitro­phen­yl)piperazin-1-ium tri­chloro­acetate

The synthesis and crystal structures of the mol­ecular salts of 4-(4-nitro­phen­yl)piperazine with tri­fluoro­acetate, namely, 4-(4-nitro­phen­yl)piperazin-1-ium tri­fluoro­acetate, C10H14N3O2+·C2F3O2− (I), and with tri­chloro­acetate, namely, 4-(4-nitro­phen­yl)piperazin-1-ium tri­chloro­acetate, C10H14N3O2+·C2Cl3O2−, (II), are reported and compared. A partial positional disorder of the anions was found. In both structures, the piperazine rings adopt a chair conformation, whereas the positions of the nitro­phenyl group on the piperazine ring differ from bis­ectional in (I) to equatorial in (II). In both structures, the supra­molecular assemblies are mono-periodic on the basis of the chain-of-rings motifs supported by aromatic π–π inter­actions. Hirshfeld surface analysis was used to explore the inter­molecular close contacts in both crystals. The most dominant contacts of the Hirshfeld surface of the cation–anion pairs of the asymmetric units are O⋯H/H⋯O, and those with a contribution of halogen atoms: F⋯H/H⋯F in (I) and Cl⋯H/H⋯Cl in (II), respectively

Synthesis and crystal structure of 2-chloro-1-(3-hy­dr­oxy­phen­yl)ethanone

The structure of 2-chloro-1-(3-hy­droxy­phen­yl)ethanone, C8H7ClO2, an α-halo­ketone is described. The mol­ecule is planar (r.m.s. deviation = 0.0164 Å) and in the crystal, inversion-symmetric dimers are formed as a result of pairs of strong O—H⋯O and weak C—H⋯O hydrogen bonds. A brief comparison is made with structurally related compounds deposited in the CSD. In addition, the synthesis and some spectroscopic details are presented

Supramolecular characterisation of salts of 4-(2-methoxyphenyl)piperazin-1-ium and 4-phenylpiperazin-1-ium cations with simple-organic anions; a closer look at the binding energies of cation-anion pairs formed by charge-assisted (+)N−H···O(-) and (+)N−H···O hydrogen bonds

Six new salts prepared by acid-base reactions containing 4-(2-methoxyphenyl)piperazin-1-ium cation (2-MeOPP) with simple organic-acid anions, namely pentafluorobenzoate, (I); (2R,3R)-tartrate dihydrate, (II); succinate trihydrate, (III); or 4-phenylpiperazin-1-ium cation (PP) with 4-chlorobenzoate monohydrate, (IV); 3-chlorobenzoate monohydrate, (V) and succinate (VI) have been structurally characterised using single-crystal X-ray diffraction. Crystal-packing architectures have been described in the context of the supramolecular assemblies they form. The most important structural motifs are generated through hydrogen bonds between 2-MeOPP or PP cations and associated anions, assisted by their charges. To quantify these charge-assisted hydrogen bonds: (+)N−H····O(-) and (+)N−H····O, the binding energies of the ionic pairs have been calculated and compared. We considered a set of 72 ionic pairs of the structures analysed in this article and those published previously by our groups. As a result, we have plotted lines of trends found for DFT-binding energies vs normalised H···O proton···acceptor distances, and correlation between normalised geometrical parameters for aromatic and aliphatic anions. A comparison between DFT-energies and model pairwise energies (CE-B3LYP) has also been made

Analytical methods for RE-Co alloys

Total RE, Co and Fe in mischmetal and its cobalt alloys are determined by visual complexometric methods and instrumental X-ray fluorescence techniques. As Fe causes interference in the determinations of RE and Co and its own determination is affected by the presence of Co, it is removed by precipitation. The iron is determined from the precipitate and RE and Co from the filtrate. Accuracy of the method is checked by analysing synthetic mixtures of RE, Co and Fe. The individual REs in mischmetal are determined by X-ray fluorescence method. The analysis technique is based on comparison of the oxides of the test samples with standards (both in pressed pellet form) in the appropriate composition range. The total RE content of mischmetal determined through complexometric analysis is compared with the total RE determined through X-ray fluorescence