Displaying publications 41 - 60 of 136 in total

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  1. Arman HD, Tiekink ER
    PMID: 24427074 DOI: 10.1107/S160053681302271X
    The asymmetric unit of title co-crystal, C10H8N2·2C7H7NO2, comprises a centrosymmetric 4,4'-bi-pyridine mol-ecule, and a 2-amino-benzoic acid mol-ecule in a general position. The latter is effectively planar [C-C-C-O torsion angle = 5.0 (3)°] owing to an intra-molecular N-H⋯O(carbon-yl) hydrogen bond. Three-mol-ecule aggregates are formed via O-H⋯N(pyrid-yl) hydrogen bonds and these are connected into supra-molecular layers in the bc plane by N-H⋯O(carbon-yl) hydrogen bonds and π-π inter-actions between pyridyl and benzene rings [inter-centroid distance = 3.634 (2) Å]. Layers are connected along the a axis by weak π-π inter-actions between benzene rings [3.964 (2) Å].
  2. Zukerman-Schpector J, Hino CL, Moran PJ, de Paula BR, Ng SW, Tiekink ER
    PMID: 24427096 DOI: 10.1107/S1600536813023374
    In the title compound, C16H20O6, the conformation about the C=C double bond [1.344 (2) Å] is Z. With respect to this bond, the ketone is almost coplanar [C-C-C-O torsion angle = -179.60 (10)°] and the ester is almost perpendicular [C-C-C-O = 78.42 (13)°]. The meth-oxy substituents of the central benzene ring are either almost coplanar [C-C-O-C = 3.54 (15) and 177.70 (9)°] or perpendicular [C-C-O-C = 80.08 12)° for the central substituent]. In the crystal, the three-dimensional architecture features C-H⋯O and π-π [inter-centroid distance = 3.6283 (6) Å] inter-actions.
  3. Arman HD, Kaulgud T, Tiekink ER
    PMID: 24427073 DOI: 10.1107/S1600536813022691
    The asymmetric unit of the title co-crystal, 2C14H13N2 (+)·C10H4O8 (2-)·2C14H12N2·C10H6O8, comprises a 2,9-dimethyl-1,10-phenanthrolin-1-ium cation (Me2PhenH(+)) and a 2,9-dimethyl-1,10-phenanthroline mol-ecule (Me2Phen), each in a general position, and half each of a 2,5-di-carb-oxy-benzene-1,4-di-carboxyl-ate dianion (LH2 (2-)) and a benzene-1,2,4,5-tetra-carb-oxy-lic acid mol-ecule (LH4), each being disposed about a centre of inversion. Small twists are evident in the dianion [the C-C-C-O torsion angles are 168.41 (18) and 16.2 (3)°], whereas a major twist is found for one carb-oxy-lic acid group in the neutral mol-ecule [C-C-C-O = 66.3 (2) and 18.2 (3)°]. The most prominent feature of the crystal packing is the formation of linear supra-molecular chains along [001] mediated by charge-assisted O-H⋯O(-) hydrogen bonding between alternating LH4 and LH2 (2-). These are connected to the Me2PhenH(+) and Me2Phen species by N-H⋯O and O-H⋯N hydrogen bonds, respectively. A three-dimensional architecture is formed by C-H⋯O and π-π inter-actions [inter-centroid distance = 3.5337 (17) Å].
  4. Arman HD, Tiekink ER
    PMID: 24427071 DOI: 10.1107/S1600536813022563
    The asymmetric unit of the title co-crystal, C10H6O8·2C8H10N4O2, comprises a centrosymmetric benzene-1,2,4,5-tetra-carb-oxy-lic acid (LH4) mol-ecule and a mol-ecule of caffeine in a general position. LH4 is nonplanar, with the dihedral angles between the ring and pendent carb-oxy-lic acid groups being 44.22 (7) and 49.74 (7)°. By contrast, the caffeine mol-ecule is planar (r.m.s. deviation = 0.040 Å). Supra-molecular layers parallel to (-1-10) are sustained by carb-oxy-lic acid O-H⋯O(carbon-yl) and O-H⋯N(imidazole) hydrogen bonds, as well as by meth-yl-carbonyl C-H⋯O inter-actions. These stack via π-π inter-actions between the benzene and imidazole rings [inter-centroid distance = 3.4503 (10) Å].
  5. Prasath R, Sarveswari S, Ng SW, Tiekink ER
    PMID: 24427050 DOI: 10.1107/S1600536813022022
    In the title ethanol solvate, C29H20Cl2N2O·C2H5OH, the quinolinyl residues form a dihedral angle of 46.41 (4)° with each other, and each is inclined [Cp-C-C=O and C=C-C-Cp (p = pyridyl) torsion angles = 54.8 (2) and 144.44 (19)°, respectively] with respect to the almost planar bridging prop-2-en-1-one residue [O=C-C=C torsion angle = -4.1 (3)°]. The ethanol solvent mol-ecule is disordered over two positions of equal occupancy and is located close to a centre of inversion. These mol-ecules reside in cavities defined by the organic mol-ecules, which are connected into a three-dimensional architecture by C-H⋯Cl, C-H⋯O and C-H⋯N inter-actions, as well as π-π contacts [inter-centroid distances = 3.5853 (10) and 3.8268 (11) Å], each involving pyridyl rings.
  6. Selvakumaran N, Karvembu R, Ng SW, Tiekink ER
    PMID: 24427014 DOI: 10.1107/S1600536813021053
    The title compound, C26H42N4O2S2, adopts a shallow U-shape as both pendant arms of the 1,3-substituted benzene ring are orientated in the same direction. The thione S atoms lie to the same side of the benzene ring and the carbonyl O atoms to the other. The most prominent feature of the crystal packing is the formation of inversion dimers mediated by N-H⋯S hydrogen bonds. One of the 2-methyl-propyl groups is statistically disordered over two positions.
  7. Arman HD, Poplaukhin P, Tiekink ER
    PMID: 24426981 DOI: 10.1107/S1600536813021569
    The asymmetric unit of title salt co-crystal, [K(C9H11N2S2)(C12H24O6)], comprises a K(+) cation, an (-)S2CN(Et)py anion and a 18-crown-6 mol-ecule. Substantial delocalization of π-electron density is evident in the di-thio-carbamate anion, as indicated by the equivalent C-S bond lengths. The K(+) cation sits within an O6S2 donor set lying 0.7506 (6) Å out of the least-squares plane through the six O atoms (r.m.s. deviation = 0.1766 Å) of the 18-crown-6 mol-ecule with the two S atoms being on one side of this plane. Supra-molecular layers in the bc plane, sustained by C-H⋯O and C-H⋯π inter-actions, feature in the crystal packing.
  8. Prasath R, Sarveswari S, Ng SW, Tiekink ER
    PMID: 24427034 DOI: 10.1107/S1600536813021545
    In the title compound, C32H21ClN2O, an almost planar (r.m.s. deviation = 0.033 Å) prop-2-en-1-one bridge links quinolinyl and benzoquinolinyl residues; the latter are twisted out of the plane of the bridge [dihedral angles = 75.94 (5) and 20.20 (5)°, respectively]. In the crystal, a three-dimensional architecture arises as a result of C-H⋯O, C-H⋯π and π-π [centroid-centroid distances involving pyridine rings = 3.5806 (7)-3.7537 (7) Å] interactions.
  9. Ishak DH, Ooi KK, Ang KP, Akim AM, Cheah YK, Nordin N, et al.
    J Inorg Biochem, 2014 Jan;130:38-51.
    PMID: 24176918 DOI: 10.1016/j.jinorgbio.2013.09.018
    The compound with R=CH2CH3 in Bi(S2CNR2)3 (1) is highly cytotoxic against a range of human carcinoma, whereas that with R=CH2CH2OH (2) is considerably less so. Both 1 and 2 induce apoptosis in HepG2 cells with some evidence for necrosis induced by 2. Based on DNA fragmentation, caspase activities and human apoptosis PCR-array analysis, both the extrinsic and intrinsic pathways of apoptosis have been shown to occur. While both compounds activate mitochondrial and FAS apoptotic pathways, compound 1 was also found to induce another death receptor-dependent pathway by induction of CD40, CD40L and TNF-R1 (p55). Further, 1 highly expressed DAPK1, a tumour suppressor, with concomitant down-regulation of XIAP and NF-κB. Cell cycle arrest at the S and G2/M phases correlates with the inhibition of the growth of HepG2 cells. The cell invasion rate of 2 is 10-fold higher than that of 1, a finding correlated with the down-regulation of survivin and XIAP expression by 1. Compounds 1 and 2 interact with DNA through different binding motifs with 1 interacting with AT- or TA-specific sites followed by inhibition of restriction enzyme digestion; 2 did not interfere with any of the studied restriction enzymes.
  10. Farag IS, Girgis AS, Ramadan AA, Moustafa AM, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Jan 01;70(Pt 1):o70-1.
    PMID: 24855471 DOI: 10.1107/S1600536813033771
    The title compound, C34H38ClN5O2, has spiro links connecting the pyrrolidine ring and indole residue, as well as the piperidine and pyrrolidine rings. A half-chair conformation is found for the piperidine ring with the C atom connected to the spiro-C atom lying 0.738 (4) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.0407 Å). The methyl-ene C atom is the flap in the envelope conformation for the pyrrolidine ring. In the crystal, supra-molecular chains are sustained by alternating eight-membered {⋯HNCO}2 and 14-membered {⋯HC5O}2 synthons. Chains are connected into a three-dimensional network by (pyrrolidine-bound phenyl-meth-yl)C-H⋯π(pyrrolidine-bound phen-yl) edge-to-face inter-actions.
  11. Farag IS, Girgis AS, Ramadan AA, Moustafa AM, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Jan 01;70(Pt 1):o43-4.
    PMID: 24855468 DOI: 10.1107/S1600536813033096
    Two spiro links are found in the title compound, C31H28Cl3N3O2, one connecting the piperidine and pyrrolidine rings, and the other connecting the pyrrolidine ring and indole residue. The piperidine ring adopts a half-chair conformation, in which the C atom connected to the spiro-C atom lies 0.741 (3) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.053 Å). The pyrrolidine ring has an envelope conformation with the flap atom being the methyl-ene C atom. Centrosymmetric eight-membered {⋯HNCO}2 amide dimers are the most significant feature of the crystal packing. These are connected into layers parallel to (-120) by C-H⋯O and π-π inter-actions between pyrrolidine-bound benzene rings [inter-centroid distance = 3.8348 (15) Å]. Slipped face-to-face inter-actions between the edges of pyrrolidine-bound benzene [shortest C⋯C separation = 3.484 (4) Å] connect the layers into a three-dimensional architecture.
  12. Farag IS, Girgis AS, Ramadan AA, Moustafa AM, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Jan 01;70(Pt 1):o22-3.
    PMID: 24855467 DOI: 10.1107/S1600536813032765
    The title compound, C30H28ClN3O2, features two spiro links, one connecting the piperidine and pyrrolidine rings, and the other connecting the pyrrolidine ring and indole residue. The configuration about the ethene bond is E. The piperidine ring adopts a half-chair conformation where the C atom connected to the spiro-C atom lies 0.713 (3) Å out of the plane of the remaining five atoms (r.m.s. deviation = 0.086 Å). The pyrrolidine ring has an envelope conformation with the flap atom being the methyl-ene C atom. Centrosymmetric eight-membered {⋯HNCO}2 amide synthons feature in the crystal packing. These are consolidated into a three-dimensional architecture by phen-yl-pyrrolidine C-H⋯N and chloro-benzene-pyrrolidine-bound phenyl C-H⋯π inter-actions.
  13. Tiekink ER, Wardell JL
    Acta Crystallogr Sect E Struct Rep Online, 2014 Feb 1;70(Pt 2):o158-9.
    PMID: 24764879 DOI: 10.1107/S1600536814000609
    In the title compound, C14H8N4O6, the benzoxazin-4-one fused-ring system (r.m.s. deviation = 0.018 Å) is coplanar with the attached benzene ring [dihedral angle = 0.81 (4)°], there being an intra-molecular N-H⋯N hydrogen bond between them. Each nitro group is twisted out of the plane of the attached benzene ring [O-N-C-C torsion angles = 167.94 (11) and 170.38 (11)°]. In the crystal, amine-nitro N-H⋯O hydrogen bonds lead to centrosymmetric dimeric aggregates that are connected into a three-dimensional architecture by oxazin-yl-nitro C-H⋯O and π-π inter-actions [inter-centroid distance between the oxazinyl and terminal benzene rings = 3.5069 (7) Å].
  14. Noguiera TC, Pinheiro AC, de Souza MV, Wardell JL, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Feb 01;70(Pt 2):o125.
    PMID: 24764853 DOI: 10.1107/S1600536814000415
    The 21 non-H atoms of the title compound, C15H10Cl2N4, are almost planar (r.m.s. deviation = 0.032 Å); the conformation about the N=C bond [1.277 (6) Å] is E. In the crystal, zigzag supra-molecular chains along the c axis (glide symmetry) are formed via N-H⋯N hydrogen bonds. These associate along the b axis by π-π inter-actions between the fused and terminal benzene rings [inter-centroid distance = 3.602 (3) Å] so that layers form in the bc plane.
  15. Sinha B, Dey GC, Sarkar B, Roy A, Ng SW, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Mar 1;70(Pt 3):m112-3.
    PMID: 24764942 DOI: 10.1107/S1600536814004280
    The title complex, [Cu{μ3-O2CC6H3(NO2)2-3,5}(μ-OH)] n , features zigzag chains in which successive pairs of Cu(II) atoms are connected by OH bridges and bidentate carboxyl-ate ligands, leading to six-membered Cu(O)(OCO)Cu rings. The zigzag chains are connected into a three-dimensional architecture by Cu-O(nitro) bonds. The coordination geometry of the Cu(II) atom is square-pyramidal, with the axial position occupied by the nitro O atom, which forms the longer Cu-O bond. Bifurcated hy-droxy-nitro O-H⋯O hydrogen bonds contribute to the stability of the crystal structure.
  16. Jan CY, Shamsudin NB, Tan AL, Young DJ, Ng SW, Tiekink ER
    PMID: 24765021 DOI: 10.1107/S1600536814003468
    In the title compound, C8H3N3O2 (systematic name: 4-nitro-benzene-1,2-dicarbo-nitrile), the nitro group is twisted out of the plane of the benzene ring to which it is attached [O-N-Cring-Cring torsion angle = 9.80 (13)°]. In the crystal packing, supra-molecular layers with a zigzag topology in the ac plane are sustained by C-H⋯N inter-actions.
  17. Jan CY, Shamsudin NB, Tan AL, Young DJ, Ng SW, Tiekink ER
    PMID: 24765000 DOI: 10.1107/S1600536814002955
    In the title compound, C8H7N3O4 (systematic name: 4-nitro-benzene-1,2-dicarboxamide), each of the substituents is twisted out of the plane of the benzene ring to which it is attached [dihedral angles of 11.36 (2)° for the nitro group, and 60.89 (6) and 34.39 (6)° for the amide groups]. The amide groups are orientated to either side of the least-squares plane through the benzene ring with the amine groups being directed furthest apart. In the crystal, a three-dimensional architecture is established by a network of N-H⋯O hydrogen bonds.
  18. Nor NA, Abdullah Z, Ng SW, Tiekink ER
    PMID: 24765029 DOI: 10.1107/S1600536814003626
    The asymmetric unit of the title cyclic thio-urea derivative, C10H12N2S, comprises two mol-ecules, each of which has a twist about the CH2-CH2 bond within the five-membered ring. The major difference between the independent mol-ecules is manifested in the relative orientations of the five- and six-membered rings [dihedral angles between the least-squares planes = 28.03 (11) and 41.54 (11)°]. A network of C-H⋯π inter-actions consolidates the three-dimensional crystal packing.
  19. Arman HD, Kaulgud T, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Apr 1;70(Pt 4):o402-3.
    PMID: 24826120 DOI: 10.1107/S1600536814004838
    The sulfa-thia-zole mol-ecule in the title 1:1 co-crystal, C9H9N3O2S2·C18H12N6, adopts an approximate L-shape [dihedral angle between the five- and six-membered rings = 86.20 (9)°] and features an intra-molecular hypervalent S⋯O inter-action [2.8666 (15) Å]. Overall, the triazine mol-ecule has the shape of a disk as the pendant pyridine rings are relatively close to coplanar with the central ring [dihedral angles = 18.35 (9), 6.12 (9) and 4.67 (9)°]. In the crystal packing, a linear supra-molecular chain aligned along [01-1] is formed as a result of amino-pyridyl N-H⋯N hydrogen bonding with syn-disposed pyridyl mol-ecules of one triazine, and amine-pyridyl N-H⋯N hydrogen bonding with the third pydridyl ring of a second triazine mol-ecule. A three-dimensional architecture arises as the chains are connected by C-H⋯O inter-actions.
  20. Gama IL, de Souza MV, Wardell JL, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Apr 01;70(Pt 4):o385-6.
    PMID: 24826110 DOI: 10.1107/S1600536814004565
    In the title salt, C11H12ClN2O(+)·Cl(-), the ten non-H atoms comprising the quinolinium residue are coplanar (r.m.s. deviation = 0.041 Å) and the hy-droxy-ethyl group is approximately perpendicular to this plane [Cring-N-Cmethyl-ene-C torsion angle = -74.61 (18)°]. A supra-molecular chain aligned along [101] mediated by charge-assisted O/N-H⋯Cl(-) hydrogen bonds features in the crystal packing. Chains are connected into a three-dimensional architecture by C-H⋯O(hy-droxy) inter-actions.
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