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Solvent Water Molecules (solvent + water_molecule)
Selected AbstractsA mixed-valence chair-like tetranuclear copper(I,II) cluster with three linking modes of the 3,5-bis(2-pyridyl)-1,2,4-triazole ligandACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2010Quan-Guo Zhai In the tetranuclear copper complex tetrakis[,-3,5-bis(2-pyridyl)-1,2,4-triazolido]bis[3,5-bis(2-pyridyl)-1,2,4-triazolido]dicopper(I)dicopper(II) dihydrate, [CuI2CuII2(C12H8N5)6]·2H2O, the asymmetric unit is composed of one CuI center, one CuII center, three anionic 3,5-bis(2-pyridyl)-1,2,4-triazole (2-BPT) ligands and one solvent water molecule. The CuI and CuII centers exhibit [CuIN4] tetrahedral and [CuIIN6] octahedral coordination environments, respectively. The three independent 2-BPT ligands adopt different chelating modes, which link the copper centers to generate a chair-like tetranuclear metallomacrocycle with metal,metal distances of about 4.4 × 6.2,Å disposed about a crystallographic inversion center. Furthermore, strong ,,, stacking interactions and O,H...N hydrogen-bonding systems link the tetracopper clusters into a two-dimensional supramolecular network. [source] Poly[[tetraaqua(,7 -pyridine-2,3,5,6-tetracarboxylato)dicadmium(II)] monohydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Sitang Yan The title compound, {[Cd2(C9HNO8)(H2O)4]·H2O}n, consists of two crystallographically independent CdII cations, one tetrabasic pyridine-2,3,5,6-tetracarboxylate (pdtc) anion, four coordinated water molecules and one solvent water molecule. The CdII cations have distorted square-antiprismatic (one pyridine N, six carboxylate O and one water O atom) and octahedral (three carboxylate O and three water O atoms) coordination environments. Each pdtc ligand employs its pyridine and carboxylate groups to chelate and bridge seven CdII cations. The square-antiprismatic coordinated CdII cations are linked by pdtc ligands into a lamellar framework structure, while the octahedral coordinated CdII cations are bridged by the ,2 -carboxylate O atoms and the pdtc ligands into a chain network that further joins neighbouring lamellae into a three-dimensional porous network. The cavities are filled with solvent water molecules that are linked to the host through complex hydrogen bonding. [source] A three-dimensional hybrid framework based on novel [Co4Mo4] bimetallic oxide clusters with 3,5-bis(3-pyridyl)-1,2,4-triazole ligandsACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2009Quan-Guo Zhai In the title organic,inorganic hybrid complex, poly[[[,-3,5-bis(3-pyridyl)-1,2,4-triazole]tri-,3 -oxido-tetra-,2 -oxido-oxidodicobalt(II)dimolybdenum(VI)] monohydrate], {[Co2Mo2O8(C12H9N5)]·H2O}n, the asymmetric unit is composed of two CoII centers, two [MoVIO4] tetrahedral units, one neutral 3,5-bis(3-pyridyl)-1,2,4-triazole (BPT) ligand and one solvent water molecule. The cobalt centers both exhibit octahedral [CoO5N] coordination environments. Four CoII and four MoVI centers are linked by ,2 -oxide and/or ,3 -oxide bridges to give an unprecedented bimetallic octanuclear [Co4Mo4O22N4] cluster, which can be regarded as the first example of a metal-substituted octamolybdate and exhibits a structure different from those of the eight octamolybdate isomers reported to date. The bimetallic oxide clusters are linked to each other through corner-sharing to give two-dimensional inorganic layers, which are further bridged by trans -BPT ligands to generate a three-dimensional organic,inorganic hybrid architecture with six-connected distorted ,-Po topology. [source] Dynamic structures of phosphodiesterase-5 active site by combined molecular dynamics simulations and hybrid quantum mechanical/molecular mechanical calculationsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 8 2008Ying Xiong Abstract Various quantum mechanical/molecular mechanical (QM/MM) geometry optimizations starting from an x-ray crystal structure and from the snapshot structures of constrained molecular dynamics (MD) simulations have been performed to characterize two dynamically stable active site structures of phosphodiesterase-5 (PDE5) in solution. The only difference between the two PDE5 structures exists in the catalytic, second bridging ligand (BL2) which is HO, or H2O. It has been shown that, whereas BL2 (i.e. HO,) in the PDE5(BL2 = HO,) structure can really bridge the two positively charged metal ions (Zn2+ and Mg2+), BL2 (i.e. H2O) in the PDE5(BL2 = H2O) structure can only coordinate Mg2+. It has been demonstrated that the results of the QM/MM geometry optimizations are remarkably affected by the solvent water molecules, the dynamics of the protein environment, and the electronic embedding charges of the MM region in the QM part of the QMM/MM calculation. The PDE5(BL2 = H2O) geometries optimized by using the QM/MM method in different ways show strong couplings between these important factors. It is interesting to note that the PDE5(BL2 = HO - ) and PDE5(BL2 = H2O) geometries determined by the QM/MM calculations neglecting these three factors are all consistent with the corresponding geometries determined by the QM/MM calculations that account for all of these three factors. These results suggest the overall effects of these three important factors on the optimized geometries can roughly cancel out. However, the QM/MM calculations that only account for some of these factors could lead to considerably different geometries. These results might be useful also in guiding future QM/MM geometry optimizations on other enzymes. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] A new adamantanecarboxylate coordination polymer: poly[[(,3 -adamantane-1,3-dicarboxylato)aquadioxidouranium(VI)] monohydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2010Julia A. Rusanova The title compound, {[U(C12H14O4)O2(H2O)]·H2O}n, is the first actinide complex featuring adamantanecarboxylate ligands. The metal ion possesses a pentagonal,bipyramidal UO7 coordination involving two axial oxide ligands [U,O = 1.732,(5) and 1.764,(5),Å] and five equatorial O atoms [U,O = 2.259,(5),2.494,(4),Å] of aqua and carboxylate ligands. The latter display pseudo-chelating and bridging coordination modes of the carboxylate groups that are responsible for the generation of the centrosymmetric discrete uranium,carboxylate [UO2(,- RCOO)2UO2] dimers [U...U = 5.5130,(5),Å] and their connection into one-dimensional chains. Hydrogen bonding involving two coordinated and two solvent water molecules [O...O = 2.719,(7),2.872,(7),Å] yields centrosymmetric (H2O)4 ensembles and provides noncovalent linkage between the coordination chains to generate a three-dimensional network structure. [source] Graphene-like nets of hydrogen-bonded water molecules in the dihydrate of 2-[(2-ammonioethyl)amino]acetate and the structure of its anhydrous hydroiodide saltACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2010Tove Wiklund 2-[(2-Ammonioethyl)amino]acetate dihydrate, better known as N -(2-aminoethyl)glycine dihydrate, C4H10N2O2·2H2O, (I), crystallizes as a three-dimensional hydrogen-bonded network. Amino acid molecules form layers in the ac plane separated by layers of water molecules, which form a hydrogen-bonded two-dimensional net composed of fused six-membered rings having boat conformations. The crystal structure of the corresponding hydroiodide salt, namely 2-[(2-ammonioethyl)ammonio]acetate iodide, C4H11N2O2+·I,, (II), has also been determined. The structure of (II) does not accommodate any solvent water molecules, and displays stacks of amino acid molecules parallel to the a axis, with iodide ions located in channels, resulting in an overall three-dimensional hydrogen-bonded network structure. N -(2-Aminoethyl)glycine is a molecule of considerable biological interest, since its polyamide derivative forms the backbone in the DNA mimic peptide nucleic acid (PNA). [source] Supramolecular association in proton-transfer adducts containing benzamidinium cations.ACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010Four organic salts, namely benzamidinidium orotate (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylate) hemihydrate, C7H9N2+·C5H3N2O4,·0.5H2O (BenzamH+·Or,), (I), benzamidinium isoorotate (2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate) trihydrate, C7H9N2+·C5H3N2O4,·3H2O (BenzamH+·Isor,), (II), benzamidinium diliturate (5-nitro-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-olate) dihydrate, C7H9N2+·C4H2N3O5,·2H2O (BenzamH+·Dil,), (III), and benzamidinium 5-nitrouracilate (5-nitro-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide), C7H9N2+·C4H2N3O4, (BenzamH+·Nit,), (IV), have been synthesized by a reaction between benzamidine (benzenecarboximidamide or Benzam) and the appropriate carboxylic acid. Proton transfer occurs to the benzamidine imino N atom. In all four acid,base adducts, the asymmetric unit consists of one tautomeric aminooxo anion (Or,, Isor,, Dil, and Nit,) and one monoprotonated benzamidinium cation (BenzamH+), plus one-half (which lies across a twofold axis), three and two solvent water molecules in (I), (II) and (III), respectively. Due to the presence of protonated benzamidine, these acid,base complexes form supramolecular synthons characterized by N+,H...O, and N+,H...N, (±)-charge-assisted hydrogen bonds (CAHB). [source] Poly[[[aqua(2,2,-bipyridine-,2N,N,)manganese(II)]-,-croconato-,4O,O,:O,,,O,,,] monohydrate]: a one-dimensional coordination polymer connected by hydrophilic,hydrophilic and lipophilic,lipophilic interactions at 135,KACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Hong-Feng Chen In the title one-dimensional coordination polymer, {[Mn(C5O5)(C10H8N2)(H2O)]·H2O}n, each MnII ion is seven-coordinated by four O atoms from two croconate ligands, two N atoms from a 2,2,-bipyridine (2,2,-bipy) ligand and one O atom from an aqua ligand. The croconate ligand bridges the MnII ions in a bis-bidentate chelation mode, forming an extended [Mn(C5O5)]n chain running parallel to the [001] direction, with the lipophilic 2,2,-bipy ligands lying along one side and the hydrophilic water molecules along the opposite side. Coordinated water and solvent water molecules are arranged in the hydrophilic layer, which is characterized by O,H...O hydrogen bonds between croconate ligands. Meanwhile, 2,2,-bipy ligands from adjacent chains partially overlap and exhibit ,,, interactions to form a lipophilic layer. The hydrophilic and lipophilic layers are arranged alternately to build a layer structure. [source] Poly[[tetraaqua(,7 -pyridine-2,3,5,6-tetracarboxylato)dicadmium(II)] monohydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Sitang Yan The title compound, {[Cd2(C9HNO8)(H2O)4]·H2O}n, consists of two crystallographically independent CdII cations, one tetrabasic pyridine-2,3,5,6-tetracarboxylate (pdtc) anion, four coordinated water molecules and one solvent water molecule. The CdII cations have distorted square-antiprismatic (one pyridine N, six carboxylate O and one water O atom) and octahedral (three carboxylate O and three water O atoms) coordination environments. Each pdtc ligand employs its pyridine and carboxylate groups to chelate and bridge seven CdII cations. The square-antiprismatic coordinated CdII cations are linked by pdtc ligands into a lamellar framework structure, while the octahedral coordinated CdII cations are bridged by the ,2 -carboxylate O atoms and the pdtc ligands into a chain network that further joins neighbouring lamellae into a three-dimensional porous network. The cavities are filled with solvent water molecules that are linked to the host through complex hydrogen bonding. [source] The hydrated and anhydrous gold(III) tetrachloride salts of l -ecgonine, an important forensic toxicology marker for cocaineACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2010Matthew R. Wood The structure of the hydrated gold(III) tetrachloride salt of l -ecgonine {hydronium tetrakis[(1R,2R,3S,5S,8S)-3-hydroxy-8-methyl-8-azoniabicyclo[3.2.1]octane-2-carboxylate pentakis[tetrachloridoaurate(III)] hexahydrate}, (C9H16NO3)4(H3O)[AuCl4]5·6H2O, demonstrates an unprecedented stoichiometric relationship between the cations and anions in the unit cell. The previous tropane alkaloid structures, including the related hydrochloride salts, all have a cation,anion ratio of 1:1, as does the anhydrous salt described here, namely (1R,2R,3S,5S,8S)-3-hydroxy-8-methyl-8-azoniabicyclo[3.2.1]octane-2-carboxylate tetrachloridoaurate(III), (C9H16NO3)[AuCl4]. The hydrated salt, however, consists of four monopositive N-protonated units of the alkaloid and five [AuCl4], counter-ions, plus seven solvent water molecules. The H atom required for change balance has been assigned to a water molecule. In addition, the hydrate has a novel arrangement, with all seven of the water molecules and all of the O atoms in the cations participating in an alternating arrangement of interleaved sheets of the anionic species. Both the hydrate and the anhydrous salt of the same toxicologically important marker for cocaine show that the cation and anion are in close proximity to each other, as was found in the gold(III) tetrachloride salt of l -cocaine. [source] Three-dimensional hydrogen-bonded structures in the 1:1 proton-transfer compounds of l -tartaric acid with the associative-group monosubstituted pyridines 3-aminopyridine, 3-carboxypyridine (nicotinic acid) and 2-carboxypyridine (picolinic acid)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2010Graham Smith The 1:1 proton-transfer compounds of l -tartaric acid with 3-aminopyridine [3-aminopyridinium hydrogen (2R,3R) -tartrate dihydrate, C5H7N2+·C4H5O6,·2H2O, (I)], pyridine-3-carboxylic acid (nicotinic acid) [anhydrous 3-carboxypyridinium hydrogen (2R,3R)-tartrate, C6H6NO2+·C4H5O6,, (II)] and pyridine-2-carboxylic acid [2-carboxypyridinium hydrogen (2R,3R)-tartrate monohydrate, C6H6NO2+·C4H5O6,·H2O, (III)] have been determined. In (I) and (II), there is a direct pyridinium,carboxyl N+,H...O hydrogen-bonding interaction, four-centred in (II), giving conjoint cyclic R12(5) associations. In contrast, the N,H...O association in (III) is with a water O-atom acceptor, which provides links to separate tartrate anions through Ohydroxy acceptors. All three compounds have the head-to-tail C(7) hydrogen-bonded chain substructures commonly associated with 1:1 proton-transfer hydrogen tartrate salts. These chains are extended into two-dimensional sheets which, in hydrates (I) and (III) additionally involve the solvent water molecules. Three-dimensional hydrogen-bonded structures are generated via crosslinking through the associative functional groups of the substituted pyridinium cations. In the sheet struture of (I), both water molecules act as donors and acceptors in interactions with separate carboxyl and hydroxy O-atom acceptors of the primary tartrate chains, closing conjoint cyclic R44(8), R34(11) and R33(12) associations. Also, in (II) and (III) there are strong cation carboxyl,carboxyl O,H...O hydrogen bonds [O...O = 2.5387,(17),Å in (II) and 2.441,(3),Å in (III)], which in (II) form part of a cyclic R22(6) inter-sheet association. This series of heteroaromatic Lewis base,hydrogen l -tartrate salts provides further examples of molecular assembly facilitated by the presence of the classical two-dimensional hydrogen-bonded hydrogen tartrate or hydrogen tartrate,water sheet substructures which are expanded into three-dimensional frameworks via peripheral cation bifunctional substituent-group crosslinking interactions. [source] Di-,-oxido-bis{bis[N,N,-bis(2-pyridylmethyl)ethane-1,2-diamine]manganese(III,IV)} tris(perchlorate) hexahydrate: clarification of an order,disorder phase transitionACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2009Anne Nielsen The title compound, [Mn2O2(C14H18N4)2](ClO4)3·6H2O, contains a mixed-valent MnIII/MnIV complex. In accordance with a previous report [Collins, Hodgson, Michelsen & Towle (1987). J. Chem. Soc. Chem. Commun. pp. 1659,1660], the structure at 295,K is best described in the space group C2/c, with the complex exhibiting twofold rotational symmetry, and with half site occupancy for one perchlorate anion and several solvent water molecules. At 180,K, the structure is ordered in the subgroup P21/n and is clearly shown to be a hexahydrate, rather than the previously reported trihydrate. The origin of the order,disorder phase transition lies in the thermal motion of the perchlorate anions. [source] Poly[[diaqua(,3 -3-nitrophthalato)calcium(II)] monohydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009Ming-Lin Guo The title 3-nitrophthalate,calcium coordination polymer, {[Ca(C8H3NO6)(H2O)2]·H2O}n, crystallizes as a one-dimensional framework. The CaII centre has a distorted pentagonal,bipyramidal geometry, being seven-coordinated by five O atoms from three different 3-nitrophthalate groups and by two water molecules, resulting in a one-dimensional zigzag chain along the a -axis direction by the interconnection of the four O atoms from the two carboxylate groups. There is a D3 water cluster composed of the coordinated and the solvent water molecules within such chains. Adjacent chains are aggregated into two-dimensional layers via hydrogen bonds in the c -axis direction. The whole three-dimensional structure is further stabilized by weak O,H...O hydrogen bonds between the O atoms of the nitro group and the water molecules. [source] Hydrogen-bond-directed supramolecular arrays in 4,4,-bipyridinium tetrachloroterephthalate dihydrate and bis(1,10-phenanthrolinium) tetrachloroterephthalate tetrachloroterephthalic acid trihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009Ming-Yang He The title compounds, C10H10N22+·C8Cl4O42,·2H2O, (I), and 2C12H9N2+·C8Cl4O42,·C8H2Cl4O4·3H2O, (II), both crystallize as charge-transfer organic salts with the dianionic or neutral acid components lying on inversion centres. The acid and base subunits in (I) arrange alternately to generate a linear tape motif via N,H...O hydrogen bonds; these tapes are further combined into a three-dimensional architecture through multiple O,H...O and C,H...O interactions involving solvent water molecules. In contrast, the neutral and anionic acid components in (II) are linked to form a zigzag chain by means of O,H...O hydrogen bonds between acid groups, with dangling 1,10-phenanthrolinium units connected to these chains by carboxylate,pyridinium interactions with R22(7) hydrogen-bond notation. Adjacent chains are further extended to result in a two-dimensional corrugated layer network via,,, interactions. Inter-ion Cl...O interactions are also found in both (I) and (II). [source] (Acetato-,O)aqua(1H -imidazole-,N3)(picolinato-,2N,O)copper(II) 0.87-hydrate: a Z,> 1 structureACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009Anne-Christine Chamayou The crystal structure of the title compound, [Cu(C6H4NO2)(C2H3O2)(C3H4N2)(H2O)]·0.87H2O, has a square-pyramidal-coordinated CuII centre (the imidazole is trans to the picolinate N atom, the acetate is trans to the picolinate ,CO2 group and the aqua ligand is in a Jahn,Teller-elongated apical position) and has two symmetry-independent molecules in the unit cell (Z, = 2), which are connected through complementary imidazole,picolinate N,H...O hydrogen bonding. The two partially occupied solvent water molecules are each disordered over two positions. The disordered solvent water molecules, together with pseudosymmetry elements, support the notion that a crystal structure with multiple identical chemical formula units in the structural asymmetric unit (Z, > 1) can represent a crystal `on the way', that is, a kinetic intermediate form which has not yet reached its thermodynamic minimum. Neighbouring molecules form ,,, stacks between their imidazole and picolinate N-heterocycles, with centroid,centroid distances in the range 3.582,(2),3.764,(2),Å. [source] Poly[[diaqua(,3 -2,2-dimethylmalonato)cadmium(II)] tetrahydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Ming-Lin Guo In the title complex, {[Cd(C5H6O4)(H2O)2]·4H2O}n, the dimethylmalonate,cadmium metal,organic framework co-exists with an extended structure of water molecules, which resembles a sodalite-type framework. In the asymmetric unit, there are five independent solvent water molecules, two of which are in special positions. The Cd atoms are eight-coordinated in a distorted square-antiprismatic geometry by six O atoms of three different dimethylmalonate groups and by two water molecules, and form a two-dimensional honeycomb layer parallel to the bc plane. Two such layers sandwich the hydrogen-bonded water layer, which has a sodalite-type structure with truncated sodalite units composed of coordinated and solvent water molecules. This work is the first example of a dimethylmalonate cadmium complex containing truncated sodalite-type water clusters. [source] Poly[[tetraaquatris(,3 -2,2-dimethylmalonato)dilanthanum(III)] monohydrate]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Ming-Lin Guo In the title complex, {[La2(C5H6O4)3(H2O)4]·H2O}n, the La atoms are connected by bridging O atoms from carboxylate groups to build, through centres of inversion, two-dimensional layers parallel to the ac plane containing decanuclear 20-membered rings. The coordinated water molecules are involved in intralayer hydrogen-bond interactions. Adjacent layers are linked via hydrogen bonding to the solvent water molecules. This work represents the first example of a new substituted malonate,lanthanide complex. [source] Bis[,3 - cis - N -(2-aminopropyl)- N,-(2-carboxylatophenyl)oxamidato(3,)]bis(2,2,-bipyridine)dichloridotetracopper(II) dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2009Yuan-Yuan Gu The title complex, bis[,3 - cis - N -(2-aminopropyl)- N,-(2-carboxylatophenyl)oxamidato(3,)]-1:2:4,7N,N,,N,,,O:O,,O,,:O,,,;2:3:4,7O,,,:N,N,,N,,,O:O,,O,,-bis(2,2,-bipyridine)-2,2N,N,;4,2N,N,-dichlorido-1,Cl,3,Cl -tetracopper(II) dihydrate, [Cu4(C12H12N3O4)2Cl2(C10H8N2)2]·2H2O, consists of a neutral cyclic tetracopper(II) system having an embedded centre of inversion and two solvent water molecules. The coordination of each CuII atom is square-pyramidal. The separations of CuII atoms bridged by cis - N -(2-aminopropyl)- N,-(2-carboxylatophenyl)oxamidate(3,) and carboxyl groups are 5.2096,(4) and 5.1961,(5),Å, respectively. A three-dimensional supramolecular structure involving hydrogen bonding and aromatic stacking is observed. [source] Three lanthanide complexes derived from itaconic acid and 2,2,-bipyridineACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2009Juan Carlos Muñoz The structures of three new polymeric lanthanide complexes, poly[[bis(2,2,-bipyridine)-,4 -itaconato-di-,3 -itaconato-digadolinium(III)] tetrahydrate], {[Gd2(C5H4O4)3(C10H8N2)2]·4H2O}n, (I), poly[diaqua(2,2,-bipyridine)di-,3 -itaconato-,2 -itaconato-digadolinium(III)], [Gd2(C5H4O4)3(C10H8N2)(H2O)2]n, (II), and poly[[bis(2,2,-bipyridine)-,4 -itaconato-di-,3 -itaconato-diholmium(III)] dihydrate], {[Ho2(C5H4O4)3(C10H8N2)2]·2H2O}n, (III), have been solved from twinned specimens. Compound (I) presents a two-dimensional polymeric structure parallel to (011) built up around two independent nine-coordinated Gd centres displaying similar GdO7N2 environments, with both N-donor atoms in each provided by a chelating 2,2,-bipyridine (bpy) unit. The coordinating O atoms are from three different itaconate (ita) anions (itaconic acid is 2-methylidenebutanedioic acid). Compound (II) also presents two independent Gd centres (one ten- and the other eight-coordinated), but the overall formula and individual coordinations are different from those of (I). The chemical unit is in this case completed by one bpy ligand, three ita anions (one of them displaying a new, hitherto unreported, ,3 - O,O,:O,,O,,:O,,, binding mode) and two aqua ligands. The whole structure is built up around a twofold rotation axis passing through both cations, as well as through the centre of the bpy ligand and one of the ita anions, thus making only half of the chemical unit independent. Finally, compound (III) presents a single independent Ho centre, a bpy unit and one and a half ita anions (one of them bisected by a twofold rotation axis) in the asymmetric unit, plus two (disordered) nonbonded solvent water molecules. In compounds (II) and (III), those ita anions bisected by a symmetry element incompatible with the internal symmetry of the ligand exhibit disorder in the C=CH2 group. [source] Bis[2-(2-hydroxyethyl)pyridinium] ,-decavanadato-bis[pentaaquamanganate(II)] tetrahydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009Lenka Kli, tincová The structure of the title compound, (C7H10NO)2[Mn2V10O28(H2O)10]·4H2O or (C5H4NHCH2CH2OH)2[{Mn(H2O)5}2V10O28]·4H2O, at 293,(2),K has triclinic (P) symmetry. The asymmetric unit consists of one half of a decavanadate anion of Ci symmetry, one [Mn(H2O)5]2+ group, one 2-(2-hydroxyethyl)pyridinium cation and two solvent water molecules. The decavanadate ion bridges between two [Mn(H2O)5]2+ groups, thus forming a dodecanuclear complex unit. Complex units are connected via a hydrogen-bonding network, forming supramolecular layers lying in the (001) plane. Cations and solvent water molecules are located between these layers. [source] Hexaquacobalt(II) bis(5-hydroxy-7-methoxy-4-oxo-2-phenyl-4H -chromene-6-sulfonate) tetrahydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2008Wu-Wu Li The title compound, [Co(H2O)6](C16H11O7S)2·4H2O, with cobalt(II) at the centre of symmetry, exhibits alternating hydrophilic and hydrophobic regions. Hydrophilic regions are generated by O,H...O hydrogen bonds among sulfonate groups, involving solvent water molecules and coordinated water molecules; ,,, stacking interactions assemble the flavone skeletons into columns which form the hydrophobic regions. A three-dimensional network is built up from an extensive array of hydrogen bonds, ,,, stacking interactions and electrostatic interactions between the cation and anion. As a salt of the sulfonated derivative of naturally occurring tectochrysin (5-hydroxy-7-methoxyflavone), this compound offers enhanced solubility and potential biological activity over the natural product. [source] A novel O,Zn bridging polymer complex of 2,6-bis[bis(carboxylatomethyl)aminomethyl]-4-methylphenolateACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2008Yuan-Yuan Zhang A new one-dimensional coordination polymer, catena -poly[[acetatohexaaqua{,4 -2,6-bis[bis(carboxylatomethyl)aminomethyl]-4-methylphenolato}trizinc(II)] octahydrate], [Zn3(C17H17N2O9)(C2H3O2)(H2O)6]·8H2O, is a trinuclear complex consisting of three zinc centers joined by a phenolate bridge and Zn(H2O)4 units. In each complex polymer unit, the three Zn atoms have different coordination modes. Of the two phenolate-bridged Zn ions, one adopts a distorted octahedral coordination composed of two carboxylate ligands, one tertiary N atom, two water molecules and the bridging phenolate ligand, while the other adopts a pyramidal geometry composed of two carboxylate ligands, one tertiary N atom from another coordination arm, one acetate anion as the counter-anion and the bridging phenolate ligand. The third type of Zn centre is represented by two independent Zn atoms lying on inversion centres. They both have an octahedral coordination consisting of four O atoms from four water molecules and two acetate carbonyl O atoms from the ligand. The latter Zn atoms join the above-mentioned binuclear complex units through O atoms of the carboxylate groups into an infinite chain. Neighboring aromatic rings are distributed above and below the chain in an alternating manner. Between the coordination chains, the Zn...Zn separations are 5.750,(4) and 6.806,(4),Å. The whole structure is stabilized by hydrogen bonds formed mainly by solvent water molecules. [source] Hydrogen-bonded supramolecular motifs in the 1:1 monohydrated molecular adduct of acetoguanaminium chloride with acetoguanamine and in 2,4,6-triaminopyrimidinediium dichloride dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2007Gustavo Portalone In the 1:1 monohydrated molecular adduct 2,4-diamino-6-methyl-1,3,5-triazin-1-ium chloride 2,4-diamino-6-methyl-1,3,5-triazine monohydrate, C4H8N5+·Cl,·C4H7N5·H2O, formed between 2,4-diamino-6-methyl-1,3,5-triazin-1-ium chloride (acetoguanaminium chloride) and 2,4-diamino-6-methyl-1,3,5-triazine (acetoguanamine), and in triaminopyrimidinediium dichloride dihydrate, C4H9N52+·2Cl,·2H2O, whose cationic component lies across a twofold rotation axis, the protonation occurs at the ring N atoms and the bond distances in the protonated molecules indicate significant bond alterations, consistent with charge-separated polar forms. The supramolecular structures of both compounds are stabilized by systems of hydrogen bonds forming complex sheets, interlinked by sets of hydrogen bonds involving the solvent water molecules and the chloride anions. [source] Structure of 2-keto-3-deoxy-6-phosphogluconate (KDPG) aldolase from Pseudomonas putidaACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2003B. J. Bell 2-Keto-3-deoxy-6-phosphogluconate (KDPG) aldolase from Pseudomonas putida is a key enzyme in the Entner,Doudoroff pathway which catalyses the cleavage of KDPG via a class I Schiff-base mechanism. The crystal structure of this enzyme has been refined to a crystallographic residual R = 17.1% (Rfree = 21.4%). The N-terminal helix caps one side of the torus of the (,,)8 -barrel and the active site is located on the opposite, carboxylic side of the barrel. The Schiff-base-forming Lys145 is coordinated by a sulfate (or phosphate) ion and two solvent water molecules. The interactions that stabilize the trimer are predominantly hydrophobic, with the exception of the cyclically permuted bonds formed between Glu132,OE1 of one molecule and Thr129,OG1 of a symmetry-equivalent molecule. Except for the N-terminal helix, the structure of KDPG aldolase from P. putida closely resembles the structure of the homologous enzyme from Escherichia coli. [source] | ||||||||||