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Two bismuth(III) coordination polymers, namely [Bi2X6(µ-dtpo)3]n [X = Cl (1), Br (2); dtpo = 2,2′-dithiobis(pyridine N-oxide)], were prepared using a crystal engineering strategy and structurally characterized by X-ray crystallography. In the isostructural compounds 1 and 2 (trigonal system, space group P-3c1), fac-configured BiX3 units as nodes are joined by the C2-symmetrical dtpo bridging ligand as spacers to generate 2D honeycomb layers with (6,3) topology. The 2D sheets stack along the [001] direction, resulting in virtually hexagonal channels parallel to this direction, which are occupied by disordered methanol and water molecules. The potential solvent area per unit cell volume is 42.2% for 1 and 44.0% for 2. Two isostructural 2D honeycomb bismuth(III) coordination, synthesized from 2,2′-dithiobis(pyridine N-oxide) and bismuth(III) halides are described. [ABSTRACT FROM AUTHOR]

Reactions of 2,2'-dithiobis(pyridine N-oxide) with various ZnII metal precursors and HgII halides are investigated and the products structurally characterized by X-ray crystallography. The crystal structures of the heteroleptic dinuclear complexes [HgX2(pyrithionate)2] (X = Br, I) are reported for the first time and that of the widely used antifungal and antifouling agent, the homoleptic dinuclear complex [Zn2(pyrithionate)4] (zinc pyrithione), is redetermined at low temperature, thereby improving the previous room temperature study in terms of precision. The encountered anionic chelate ligand pyrithionate results from reductive cleavage of the disulfide bond of 2,2'-dithiobis(pyridine N-oxide). [ABSTRACT FROM AUTHOR]

Reactions of 2,2'-dithiobis(pyridine N-oxide) with various ZnII metal precursors and HgII halides are investigated and the products structurally characterized by X-ray crystallography. The crystal structures of the heteroleptic dinuclear complexes [HgX2(pyrithionate)2] (X = Br, I) are reported for the first time and that of the widely used antifungal and antifouling agent, the homoleptic dinuclear complex [Zn2(pyrithionate)4] (zinc pyrithione), is redetermined at low temperature, thereby improving the previous room temperature study in terms of precision. The encountered anionic chelate ligand pyrithionate results from reductive cleavage of the disulfide bond of 2,2'-dithiobis(pyridine N-oxide). [ABSTRACT FROM AUTHOR]

The crystal structures of the methanol nitrobenzene sesquisolvate hemihydrate ( 1) and the 3.75-dimethyl sulfoxide solvate monohydrate ( 2) of 5,10,15,20-tetra(4-hydroxyphenyl)porphyrinatocopper(II) (CuTOHPP) are reported. Both 1 and 2 crystallise in the triclinic system with two molecules of the metalloporphyrin in the asymmetric unit (Z′ = 2). Compound 1 exhibits an extended two-dimensional hydrogen-bonded network in the crystal, whereas discrete hydrogen-bonded assemblies of CuTOHPP and solvent molecules are found in 2. Face-to-face stacking of the metalloporphyrin units and O-H⋯O hydrogen bonding interactions are identified as the most important solid-state organisational features in both 1 and 2. Saddle distortion of the metalloporphyrin units is encountered in both new solvates and there are no Cu⋯O interactions, despite four hydroxy groups on each porphyrin ligand and the presence of oxygen donor solvent molecules. Graphical Abstract: The methanol nitrobenzene sesquisolvate hemihydrate and the 3.75-dimethyl sulfoxide solvate monohydrate of 5,10,15,20-tetra(4-hydroxyphenyl)porphyrinatocopper(II) both crystallise in the triclinic system with two molecules in the asymmetric unit (Z′ = 2), featuring face-to-face stacking of the saddle-distorted metalloporphyrin units. [ABSTRACT FROM AUTHOR]

The crystal structure of [ZnBr( μ-dtdp)] ( 1) (dtdp = 4,4'-dithiodipyridine) is described. Compound 1 is a one-dimensional coordination polymer of the arched chain type, composed of ZnBr units as tetrahedral metal nodes joined by the bent bridging ligand dtdp. 1 was found to crystallise in the monoclinic space group C2/ c with the lattice parameters a = 12.713(4) Å, b = 10.108(4) Å, c = 10.835(5) Å, β = 91.21(3)°, V = 1392.0(9) Å. In the crystal, the coordination polymer strands run parallel to the c axis direction with the ZnBr units and disulfide bridges containing crystallographic twofold rotation axes. The structure of 1 belongs to an isomorphous series of [Zn X( μ-dtdp)] ( X = Cl, SCN, CHCOO) coordination polymers, which can be found in the literature. The crystal of 1 studied was found to be a two component non-merohedral twin with the twin operation representing a twofold rotation about the c axis, as for the isostructural chlorido derivative [Seidel RW, Dietz C, Oppel IM (2012) Z Kristallogr NCS 227:305]. Graphical Abstract: The crystal structure of the one-dimensional coordination polymer [ZnBr( μ-dtdp)] (dtdp = 4,4'-dithiodipyridine) has been determined from a non-merohedrally twinned crystal[Figure not available: see fulltext.]. [ABSTRACT FROM AUTHOR]

The crystal-to-crystal phase transition of the previously reported dinuclear C-symmetric complex [{Cu(NO)(phen)}(4,4′-bipy)] ( 1) (phen = 1,10-phenanthroline; 4,4′-bipy = 4,4′-bipyridine) [Seidel et al . (2011) Z Anorg 637:1545-1554, ] was studied in detail by differential scanning calorimetry (DSC), powder X-ray diffraction and variable temperature determinations of the unit cell parameters on a single-crystal. A density functional theory (DFT) study was undertaken to elucidate effects of crystal packing on the molecular structure in the solid-state. The DFT study confirmed that the molecular structures of 1 found in the solid-state do not represent the minimum energy conformation of the free molecule, especially with respect to the twist of the 4,4′-bipy bridging ligand. The DSC analysis revealed that the phase transition is a fully reversible process, and suggests that the relationship between the dimorphic forms of 1 is enantiotropic. [ABSTRACT FROM AUTHOR]

Reaction of Zn(NO)·6HO with the bent bridging ligand 4,4′-dithiodipyridine (dtdp), showing axial chirality, in the presence of the chelating 1,10-phenanthroline (phen) ligand in ethanol yielded [{Zn( μ-dtdp)(HO)}(NO)·2CHOH·2HO] ( 1). In 1, Zn ions are linked by two dtdp ligands of opposite chirality into a one-dimensional coordination polymer of the repeated-rhomboid type; the phen co-ligand was not encountered in the crystal. Pseudo-symmetry of the lattice is discussed for 1. Reaction of Zn(NO)·6HO and dtdp in an ethanol/water mixture in absence of phen led to the known repeated-rhomboid coordination polymer [{Zn(NO)( μ-dtdp)(HO)}NO·4HO] ( 2), the crystal structure of which was redetermined at 110 K. At low temperature, the nitrato-κ O ligand in one axial position of Zn was found to be non-disordered as distinct from the room temperature structure (Horikoshi and Mikuriya, Cryst Growth Des 5:223-230, ). The Zn ions in 2 are joined by two dtdp ligands of the same chirality. [ABSTRACT FROM AUTHOR]

Biogas is considered to be one of the potential and viable renewable energy resources. However, the presence of CO2 in biogas increases the cost of its transportation. Therefore, the removal of CO2 is of utmost essential to ensure the economic viability of the bio-gas utilisation technology. Among the various routes, pressure swing adsorption (PSA) may be considered more economically viable when adsorbent selectivity is high and heat of adsorption is low. In this work, we have synthesized mesoporous cerium oxide (CeO2) and zirconium hydroxide (Zr(OH)4) which possess approximately two orders of magnitude higher selectivity for the removal of CO2 from biogas mixture compared to commercial zeolite (Na-Zeolite Y) and commercial granular activated carbon. In addition, the methane slip in CeO2 (0.16%) was five times lower than Zr(OH)4 (0.62%) and two orders of magnitude lower than activated carbon (18%). The high selectivity and low methane slip of ceria can be attributed to the large number of heterogeneous sites available for selective adsorption of CO2. Based on our results on CO2 selectivity and methane loss, we conclude that CeO2 could be a potential adsorbent for biogas purification using PSA. [ABSTRACT FROM AUTHOR]