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Poplaukhin P.,Chemical Abstracts Service | Tiekink E.R.T.,Nanyang Technological University | Tiekink E.R.T.,University of Malaya
CrystEngComm | Year: 2010

Supramolecular interwoven double chains are found in two isomeric zinc thiolate complexes which differ in terms of the tautomeric forms of the bridging ligands, i.e. 3-NC5H4CH2N(H)C(O)C(O)N(H) CH2C5H4N-3 or 3-NC5H 4CH2NC(OH)C(OH)NCH2C5H 4N-3. In each case, the bridging ligands are threaded through 28-membered rings mediated by O-H⋯O hydrogen bonding. Hydrogen bonding interactions between the rings and threading molecules, i.e. O-H⋯O carbonyl or O-H⋯Nimine, are dependent on the tautomeric form of the threading molecules. © 2010 The Royal Society of Chemistry.

Arman H.D.,University of Texas at San Antonio | Kaulgud T.,University of Texas at San Antonio | Miller T.,University of Texas at San Antonio | Poplaukhin P.,Chemical Abstracts Service | Tiekink E.R.T.,University of Malaya
Journal of Chemical Crystallography | Year: 2012

The common feature of each of the title 2:1 cocrystals is the formation of the O-H⋯N(pyridyl) hydrogen bonds leading to three-molecule aggregates. The persistent formation of the O-H⋯N(pyridyl) hydrogen bonds where other functionalities are present, e.g. amide, indicates the robustness of this supramolecular synthon. In the structure of the 2:1 4-nitrophenylacetic acid N,N'-bis (pyridin-3-ylmethyl)oxalamide cocrystal, (1), the amide-H forms a hydrogen bond with the hydroxyl group so that rows of N,N'-bis(pyridin-3- ylmethyl)oxalamide molecules are linked into a supramolecular tape via 4-nitrophenylacetic acid molecules. In the N,N'-bis(pyridin-3-ylmethyl) thioxalamide derivative, (2), the thioamide-H atom only forms an intramolecular N-H⋯S contact. Nevertheless, a supramolecular tape is formed but mediated by C-H⋯O(nitro) interactions. Compound (1) crystallizes in the triclinic space group P1 with a = 8.195(2) Å , b = 9.502(3) Å , c = 9.999(3) Å , α = 90.631(3)8, β = 102.796(5)8, γ = 108.075(5)8, and Z = 1 (three molecule aggregate). Compound (2) also crystallizes in the triclinic space group P1with a = 8.0772(12)Å , b = 10.2111(12) Å , c = 10.2563(17) Å , α = 71.319(10)8, β = 77.777(11)8, γ = 67.660(9)8, andZ = 1 (threemolecule aggregate). © Springer Science+Business Media, LLC 2012.

Arman H.D.,University of Texas at San Antonio | Miller T.,University of Texas at San Antonio | Poplaukhin P.,Chemical Abstracts Service | Tiekink E.R.T.,University of Malaya
Zeitschrift fur Kristallographie | Year: 2013

The co-crystallisation of two equivalents of 2,6- dinitrobenzoic acid (1) with one equivalent of a member of the isomeric N,N′-bis(pyridin-n- ylmethyl)ethanediamides, n = 2, 3 and 4, resulted in the anticipated 2 : 1 salts, 2-4. The central core, i.e. CH2N(H)C(= O)C(= O)N(H)CH 2, of the isomeric di-cations are superimposable and chemically equivalent pairs of carbonyl, amide and pyridinium groups have an anti conformation. By contrast, the relative orientations of the terminal pyridinium rings from the central core vary significantly across the series as do the relative disposition of the acidic-H atoms. This feature of the structure influences the nature of N-H...O hydrogen bonding and, therefore, the observed supramolecular aggregation patterns. Thus, in 2, the syn-disposition of the nitrogenbound hydrogen atoms enables the benzoate residue to interact via the two oxygen atoms with both pyridiniumand amine-H atoms to yield a zero-dimensional aggregate. By contrast, in each of 3 and 4, having further distance between the acidic-H atoms, the benzoate residues still interact (either through one both or both oxygen atoms) with pyridinium- and amine-H atoms but those derived from symmetry related molecules to generate one-dimensional aggregates. The three-dimensional architectures of 1-3 are consolidated, in the main, by C-H...O interactions. The structure of 1 revealed the benzoic acid residue to be perpendicular in contrast to the co-planar conformations of the nitro groups. In the crystal packing, O-H...O hydrogen bonding lead to a helical supramolecular chain. © 2013 by Oldenbourg Wissenschaftsverlag, München.

Arman H.D.,University of Texas at San Antonio | Poplaukhin P.,Chemical Abstracts Service | Tiekink E.R.T.,University of Malaya
Acta Crystallographica Section E: Structure Reports Online | Year: 2012

The asymmetric unit of the title compound, [Zn(C 4H 8NOS 2) 2(C 18H 12N 6)]·1.5C 4H 8O 2, comprises a Zn-containing molecule and one and a half dioxane molecules as one of the solvent molecules is located about a crystallographic inversion centre. The approximately squarepyramidal N 3S 2 donor set is defined by two monodentate dithiocarbamate ligands and two pyridine and one triazine N atom from the tridentate triazine ligand. molecules are connected into a supramolecular array via O - H⋯S and O - H⋯N hydrogen bonds. These stack along the b axis and the solvent molecules reside in the channels thus formed.

Poplaukhin P.,Chemical Abstracts Service | Arman H.D.,University of Texas at San Antonio | Tiekink E.R.T.,University of Malaya
Zeitschrift fur Kristallographie | Year: 2012

Distinct molecular structures and supramolecular association is found in the title crystal structures. When chloroform was diffused into a solution of {Zn[S 2CN(Me)CH 2CH 2OH)] 2} 2(N,N'-bis(pyridin-3-ylmethyl) thioxalamide) in acetonitrile, it was found to have cocrystallised (2 : 1) with S 8 (1) as partial desulphurisation had occurred during crystallisation. By contrast, when dimethylformamide was diffused in an acetonitrile solution of the same compound, a 2 : 1 dimethylformamide solvate (2) was isolated. The zinc atom coordination geometry is based on a NS4 donor set in each case but, this defines an approximate square pyramidal geometry in (1) and a geometry intermediate between square pyramidal and trigonal bipyramidal in (2). This difference is ascribed to the hydrogen bonding considerations. The hydroxyl groups in (1) self-associate leading to a two-dimensional array; the S 8 molecules occupy space between successive layers. The aforementioned hydrogen bonding is disrupted in (2) where one hydroxyl group interacts with the solvent dimethylformamide molecule. Accordingly, the supramolecular association between molecules is restricted to a onedimensional chain. © by Oldenbourg Wissenschaftsverlag, München.

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