Displaying publications 21 - 40 of 136 in total

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  1. Jotani MM, Iniyavan P, Vijayakumar V, Sarveswari S, Tan YS, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Jun 01;72(Pt 6):809-14.
    PMID: 27308048 DOI: 10.1107/S2056989016007775
    In the title compound, C26H24O5, the pyran ring has a flattened-boat con-formation, with the 1,4-related ether O and methine C atoms lying 0.1205 (18) and 0.271 (2) Å, respectively, above the least-squares plane involving the doubly bonded C atoms (r.m.s deviation = 0.0208 Å). An envelope conformation is found for the cyclo-hexene ring, with the flap atom being the middle methyl-ene C atom, lying 0.616 (2) Å out of the plane defined by the remaining atoms (r.m.s. deviation = 0.0173 Å). The fused four-ring system is approximately planar, with the dihedral angle between the least-squares planes through the cyclo-hexene and naphthyl rings being 10.78 (7)°. The tris-ubstituted benzene ring occupies a position almost perpendicular to the pyran ring [dihedral angle = 83.97 (4)°]. The most prominent feature of the packing is the formation of zigzag supra-molecular chains mediated by aryl-C-H⋯O(meth-oxy) inter-actions; chains are connected into a three-dimensional architecture by methyl-ene- and methyl-C-H⋯π inter-actions. The prevalence of C-H⋯O and C-H⋯π inter-actions is confirmed by an analysis of the Hirshfeld surface. A comparison with related structures suggests that the mol-ecular conformation of the title compound is relatively robust with respect to varying substitution patterns at the methine C atom of the pyran ring.
  2. Wardell JL, Wardell SM, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Jun 01;72(Pt 6):872-7.
    PMID: 27308063 DOI: 10.1107/S2056989016008495
    The asymmetric unit of the title salt, C17H17F6N2O(+)·C10H8F3O3 (-), comprises two piperidin-1-ium cations and two carboxyl-ate anions. The cations, each having an l-shaped conformation owing to the near orthogonal relationship between the quinolinyl and piperidin-1-ium residues, are pseudo-enanti-omeric. The anions have the same absolute configuration but differ in the relative orientations of the carboxyl-ate, meth-oxy and benzene groups. Arguably, the most prominent difference between the anions occurs about the Cq-Om bond as seen in the Cc-Cq-Om-Cm torsion angles of -176.1 (3) and -67.1 (4)°, respectively (q = quaternary, m = meth-oxy and c = carboxyl-ate). The presence of Oh-H⋯Oc and Np-H⋯Oc hydrogen bonds leads to the formation of a supra-molecular chain along the a axis (h = hy-droxy and p = piperidin-1-ium); weak intra-molecular Np-H⋯Oh hydrogen bonds are also noted. Chains are connected into a three-dimensional architecture by C-H⋯F inter-actions. Based on a literature survey, related mol-ecules/cations adopt a uniform conformation in the solid state based on the letter L.
  3. Yusof EN, Jotani MM, Tiekink ER, Ravoof TB
    Acta Crystallogr E Crystallogr Commun, 2016 Apr 01;72(Pt 4):516-21.
    PMID: 27375879 DOI: 10.1107/S2056989016004291
    The title di-thio-carbazate ester, C16H16N2O2S2, comprises two almost planar residues, i.e. the phenyl ring and the remaining 14 non-H atoms (r.m.s. deviation = 0.0410 Å). These are orientated perpendicularly, forming a dihedral angle of 82.72 (5)°. An intra-molecular hy-droxy-O-H⋯N(imine) hydrogen bond, leading to an S(6) loop, is noted. An analysis of the geometric parameters is consistent with the mol-ecule existing as the thione tautomer, and the conformation about the C=N bond is E. The thione S and imine H atoms lie to the same side of the mol-ecule, facilitating the formation of inter-molecular N-H⋯S hydrogen bonds leading to eight-membered {⋯HNCS}2 synthons in the crystal. These aggregates are connected by phenyl-C-H⋯O(hy-droxy) inter-actions into a supra-molecular layer in the bc plane; these stack with no directional inter-actions between them. An analysis of the Hirshfeld surface confirms the nature of the inter-molecular inter-actions.
  4. Shamsudin N, Tan AL, Young DJ, Jotani MM, Otero-de-la-Roza A, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Apr 01;72(Pt 4):563-9.
    PMID: 27375890 DOI: 10.1107/S2056989016004722
    In the solid state, the title compound, C18H13N5O, adopts a conformation whereby the phenyl ring and meth-oxy-benzene-1,2-dicarbo-nitrile residue (r.m.s. deviation of the 12 non-H atoms = 0.041 Å) lie to opposite sides of the central triazolyl ring, forming dihedral angles of 79.30 (13) and 64.59 (10)°, respectively; the dihedral angle between the outer rings is 14.88 (9)°. This conformation is nearly 7 kcal mol(-1) higher in energy than the energy-minimized structure which has a syn disposition of the outer rings, enabling intra-molecular π-π inter-actions. In the crystal, methyl-ene-C-H⋯N(triazol-yl) and carbo-nitrile-N⋯π(benzene) inter-actions lead to supra-molecular chains along the a axis. Supra-molecular layers in the ab plane arise as the chains are connected by benzene-C-H⋯N(carbo-nitrile) inter-actions; layers stack with no directional inter-actions between them. The specified inter-molecular contacts along with other, weaker contributions to the supra-molecular stabilization are analysed in a Hirshfeld surface analysis.
  5. Syed S, Jotani MM, Halim SN, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Mar 1;72(Pt 3):391-8.
    PMID: 27006815 DOI: 10.1107/S2056989016002735
    The asymmetric unit of the title 2:1 co-crystal, 2C8H8O2·C14H14N4O2, comprises an acid mol-ecule in a general position and half a di-amide mol-ecule, the latter being located about a centre of inversion. In the acid, the carb-oxy-lic acid group is twisted out of the plane of the benzene ring to which it is attached [dihedral angle = 28.51 (8)°] and the carbonyl O atom and methyl group lie approximately to the same side of the mol-ecule [hy-droxy-O-C-C-C(H) torsion angle = -27.92 (17)°]. In the di-amide, the central C4N2O2 core is almost planar (r.m.s. deviation = 0.031 Å), and the pyridyl rings are perpendicular, lying to either side of the central plane [central residue/pyridyl dihedral angle = 88.60 (5)°]. In the mol-ecular packing, three-mol-ecule aggregates are formed via hy-droxy-O-H⋯N(pyrid-yl) hydrogen bonds. These are connected into a supra-molecular layer parallel to (12[Formula: see text]) via amide-N-H⋯O(carbon-yl) hydrogen bonds, as well as methyl-ene-C-H⋯O(amide) inter-actions. Significant π-π inter-actions occur between benzene/benzene, pyrid-yl/benzene and pyrid-yl/pyridyl rings within and between layers to consolidate the three-dimensional packing.
  6. Safbri SA, Halim SN, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Feb 1;72(Pt 2):203-8.
    PMID: 26958388 DOI: 10.1107/S2056989016000700
    The common feature of the title compounds, [Zn(C5H10NO2S2)2(C10H8N2)]·2H2O, (I), and [Zn(C6H12NOS2)2(C10H8N2)], (II), is the location of the Zn(II) atoms on a twofold rotation axis. Further, each Zn(II) atom is chelated by two symmetry-equivalent and symmetrically coordinating di-thio-carbamate ligands and a 2,2'-bi-pyridine ligand. The resulting N2S4 coordination geometry is based on a highly distorted octa-hedron in each case. In the mol-ecular packing of (I), supra-molecular ladders mediated by O-H⋯O hydrogen bonding are found whereby the uprights are defined by {⋯HO(water)⋯HO(hy-droxy)⋯} n chains parallel to the a axis and with the rungs defined by 'Zn[S2CN(CH2CH2)2]2'. The water mol-ecules connect the ladders into a supra-molecular layer parallel to the ab plane via water-O-H⋯S and pyridyl-C-H⋯O(water) inter-actions, with the connections between layers being of the type pyridyl-C-H⋯S. In (II), supra-molecular layers parallel to the ab plane are sustained by hy-droxy-O-H⋯S hydrogen bonds with connections between layers being of the type pyridyl-C-H⋯S.
  7. Safbri SA, Halim SN, Jotani MM, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Feb 1;72(Pt 2):158-63.
    PMID: 26958378 DOI: 10.1107/S2056989016000165
    The title compound, [Cd(C6H12NOS2)2(C4H10N2)], features a distorted square-pyramidal coordination geometry about the central Cd(II) atom. The di-thio-carbamate ligands are chelating, forming similar Cd-S bond lengths and define the approximate basal plane. One of the N atoms of the piperazine mol-ecule, which adopts a chair conformation, occupies the apical site. In the crystal, supra-molecular layers propagating in the ac plane are formed via hy-droxy-O-H⋯O(hy-droxy), hy-droxy-O-H⋯N(terminal-piperazine) and coordinated-piperazine-N-H⋯O(hy-droxy) hydrogen bonds; the layers also feature methine-C-H⋯S inter-actions and S⋯S [3.3714 (10) Å] short contacts. The layers stack along the b-axis direction with very weak terminal-piperazine-N-H⋯O(hy-droxy) inter-actions between them. An evaluation of the Hirshfeld surfaces confirms the importance of inter-molecular inter-actions involving oxygen and sulfur atoms.
  8. Jotani MM, Syed S, Halim SN, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Feb 01;72(Pt 2):241-8.
    PMID: 26958398 DOI: 10.1107/S2056989016000980
    The asymmetric unit of the title salt, C14H16N4O2 (2+)·2C9H5O6 (-), comprises half a dication, being located about a centre of inversion, and one anion, in a general position. The central C4N2O2 group of atoms in the dication are almost planar (r.m.s. deviation = 0.009 Å), and the carbonyl groups lie in an anti disposition to enable the formation of intra-molecular amide-N-H⋯O(carbon-yl) hydrogen bonds. To a first approximation, the pyridinium and amide N atoms lie to the same side of the mol-ecule [Npy-C-C-Namide torsion angle = 34.8 (2)°], and the anti pyridinium rings are approximately perpendicular to the central part of the mol-ecule [dihedral angle = 68.21 (8)°]. In the anion, one carboxyl-ate group is almost coplanar with the ring to which it is connected [Cben-Cben-Cq-O torsion angle = 2.0 (3)°], whereas the other carboxyl-ate and carb-oxy-lic acid groups are twisted out of the plane [torsion angles = 16.4 (3) and 15.3 (3)°, respectively]. In the crystal, anions assemble into layers parallel to (10-4) via hy-droxy-O-H⋯O(carbon-yl) and charge-assisted hy-droxy-O-H⋯O(carboxyl-ate) hydrogen bonds. The dications are linked into supra-molecular tapes by amide-N-H⋯O(amide) hydrogen bonds, and thread through the voids in the anionic layers, being connected by charge-assisted pyridinium-N-O(carboxyl-ate) hydrogen bonds, so that a three-dimensional architecture ensues. An analysis of the Hirshfeld surface points to the importance of O-H⋯O hydrogen bonding in the crystal structure.
  9. Syed S, Halim SN, Jotani MM, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Jan 01;72(Pt 1):76-82.
    PMID: 26870591 DOI: 10.1107/S2056989015024068
    The title 2:1 co-crystal, 2C7H5NO4·C14H14N4O2, in which the complete di-amide mol-ecule is generated by crystallographic inversion symmetry, features a three-mol-ecule aggregate sustained by hydroxyl-O-H⋯N(pyrid-yl) hydrogen bonds. The p-nitro-benzoic acid mol-ecule is non-planar, exhibiting twists of both the carb-oxy-lic acid and nitro groups, which form dihedral angles of 10.16 (9) and 4.24 (4)°, respectively, with the benzene ring. The di-amide mol-ecule has a conformation approximating to a Z shape, with the pyridyl rings lying to either side of the central, almost planar di-amide residue (r.m.s. deviation of the eight atoms being 0.025 Å), and forming dihedral angles of 77.22 (6)° with it. In the crystal, three-mol-ecule aggregates are linked into a linear supra-molecular ladder sustained by amide-N-H⋯O(nitro) hydrogen bonds and orientated along [10-4]. The ladders are connected into a double layer via pyridyl- and benzene-C-H⋯O(amide) inter-actions, which, in turn, are connected into a three-dimensional architecture via π-π stacking inter-actions between pyridyl and benzene rings [inter-centroid distance = 3.6947 (8) Å]. An evaluation of the Hirshfeld surfaces confirm the importance of inter-molecular inter-actions involving oxygen atoms as well as the π-π inter-actions.
  10. Ravoof TB, Tiekink ER, Omar SA, Begum SZ, Tahir MI
    Acta Crystallogr E Crystallogr Commun, 2015 Dec 1;71(Pt 12):o1071-2.
    PMID: 26870503 DOI: 10.1107/S205698901502407X
    In the title di-thio-carbazate compound, C17H19N3S2, the central CN2S2 residue is essentially planar (r.m.s. deviation = 0.0288 Å) and forms dihedral angles of 9.77 (8) and 77.47 (7)° with the substituted-pyridyl and p-tolyl rings, respectively, indicating a highly twisted mol-ecule; the dihedral angle between the rings is 85.56 (8)°. The configuration about the C=N bond is Z, which allows for the formation of an intra-molecular N-H⋯N(pyrid-yl) hydrogen bond. The packing features tolyl-methyl-C-H⋯N(imine), pyridyl-C-H⋯π(tol-yl) and π-π inter-actions [between pyridyl rings with a distance = 3.7946 (13) Å], which generates jagged supra-molecular layers that stack along the b axis with no directional inter-actions between them.
  11. Tan MY, Crouse KA, Ravoof TB, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Dec 1;71(Pt 12):o1047-8.
    PMID: 26870491 DOI: 10.1107/S2056989015023531
    In the title thio-semicarbazone compound, C18H18ClN3S, the CN3S residue is almost planar (r.m.s. deviation = 0.0031 Å) and forms dihedral angles of 65.99 (7) and 34.60 (10)° with the phenyl and chloro-benzene rings, respectively; the dihedral angle between the aromatic rings is 85.13 (8)°. The conformation about the C=N bond is Z, and that about the C=C bonds is E. The imine N and ethyl N atoms are syn and are linked by an eth-yl-imine N-H⋯N hydrogen bond. This H atom also forms an inter-molecular hydrogen bond to the thione S atom, resulting in a supra-molecular helical chain propagating along the b axis. The chains are consolidated into a three-dimensional architecture by phenyl-C-H⋯Cl contacts and weak π-π inter-actions between centrosymmetrically related chloro-benzene rings [inter-centroid distance = 3.9127 (15) Å].
  12. Asiri AM, Faidallah HM, Sobahi TR, Ng SW, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Nov 1;71(Pt 11):e4.
    PMID: 26617187 DOI: 10.1107/S2056989015019271
    In the paper by Asiri et al. [Acta Cryst. (2012), E68, o1154], the title and the chemical name of one of the reagents used in the synthesis are corrected.[This corrects the article DOI: 10.1107/S1600536812011579.].
  13. Yeo CI, Tan YS, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Oct 1;71(Pt 10):1159-64.
    PMID: 26594396 DOI: 10.1107/S2056989015016655
    The crystal and mol-ecular structures of the title salt, C8H8N3S2 (+)·Cl(-), (I), and salt hydrate, C8H7ClN3S2 (+)·Cl(-)·H2O, (II), are described. The heterocyclic ring in (I) is statistically planar and forms a dihedral angle of 9.05 (12)° with the pendant phenyl ring. The comparable angle in (II) is 15.60 (12)°, indicating a greater twist in this cation. An evaluation of the bond lengths in the H2N-C-N-C-N sequence of each cation indicates significant delocalization of π-electron density over these atoms. The common feature of the crystal packing in (I) and (II) is the formation of charge-assisted amino-N-H⋯Cl(-) hydrogen bonds, leading to helical chains in (I) and zigzag chains in (II). In (I), these are linked by chains mediated by charge-assisted iminium-N(+)-H⋯Cl(-) hydrogen bonds into a three-dimensional architecture. In (II), the chains are linked into a layer by charge-assisted water-O-H⋯Cl(-) and water-O-H⋯O(water) hydrogen bonds with charge-assisted iminium-N(+)-H⋯O(water) hydrogen bonds providing the connections between the layers to generate the three-dimensional packing. In (II), the chloride anion and water mol-ecules are resolved into two proximate sites with the major component being present with a site occupancy factor of 0.9327 (18).
  14. Tan YS, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Oct 1;71(Pt 10):1143-6.
    PMID: 26594392 DOI: 10.1107/S2056989015016382
    The asymmetric unit of the title compound, {(C34H28FeP2)[Au(C5H8NS2)]2}, comprises half a mol-ecule, with the full mol-ecule being generated by the application of a centre of inversion. The independent Au(I) atom is coordinated by thiol-ate S and phosphane P atoms that define an approximate linear geometry [S-Au-P = 169.35 (3)°]. The deviation from the ideal linear is traced to the close approach of the (intra-molecular) non-coordinating thione S atom [Au⋯S = 3.1538 (8) Å]. Supra-molecular layers parallel to (100) feature in the crystal packing, being sustained by phen-yl-thione C-H⋯S inter-actions, with the non-coordinating thione S atom in the role of a dual acceptor. Layers stack with no specific inter-actions between them.
  15. Jotani MM, Gajera NN, Patel MC, Sung HH, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Oct 1;71(Pt 10):1121-4.
    PMID: 26594387 DOI: 10.1107/S2056989015016023
    The title compound, C17H15N3O2, is a monoclinic polymorph (P21/c with Z' = 1) of the previously reported triclinic (P-1 with Z' = 2) form [Gajera et al. (2013 ▸). Acta Cryst. E69, o736-o737]. The mol-ecule in the monoclinic polymorph features a central pyrazolyl ring with an N-bound p-tolyl group and a C-bound 1,3-benzodioxolyl fused-ring system on either side of the C atom bearing the amino group. The dihedral angles between the central ring and the N- and C-bound rings are 50.06 (5) and 27.27 (5)°, respectively. The angle between the pendent rings is 77.31 (4)°, indicating the mol-ecule has a twisted conformation. The five-membered dioxolyl ring has an envelope conformation with the methyl-ene C atom being the flap. The relative disposition of the amino and dioxolyl substituents is syn. One of the independent mol-ecules in the triclinic form has a similar syn disposition but the other has an anti arrangement of these substituents. In the crystal structure of the monoclinic form, mol-ecules assemble into supra-molecular helical chains via amino-pyrazolyl N-H⋯N hydrogen bonds. These are linked into layers via C-H⋯π inter-actions, and layers stack along the a axis with no specific inter-actions between them.
  16. Jotani MM, Yeo CI, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Oct 01;71(Pt 10):1236-41.
    PMID: 26594415 DOI: 10.1107/S2056989015017624
    In the title thio-semicarbazone, C11H15N3S, the p-tolyl-N-H and imino-N-H groups are anti and syn, respectively, to the central thione-S atom. This allows for the formation of an intra-molecular p-tolyl-N-H⋯N(imino) hydrogen bond. The mol-ecule is twisted with the dihedral angle between the p-tolyl ring and the non-hydrogen atoms of the N=CMe2 residue being 29.27 (8)°. The crystal packing features supra-molecular layers lying in the bc plane whereby centrosymmetric aggregates sustained by eight-membered thio-amide {⋯HNCS}2 synthons are linked by further N-H⋯S hydrogen bonds. Layers are connected via methyl-C-H⋯π inter-actions. The supra-molecular aggregation was further investigated by an analysis of the Hirshfeld surface and comparison made to related structures.
  17. Tan YS, Ooi KK, Ang KP, Akim AM, Cheah YK, Halim SN, et al.
    J Inorg Biochem, 2015 Sep;150:48-62.
    PMID: 26086852 DOI: 10.1016/j.jinorgbio.2015.06.009
    In the solid state each of three binuclear zinc dithiocarbamates bearing hydroxyethyl groups, {Zn[S2CN(R)CH2CH2OH]2}2 for R = iPr (1), CH2CH2OH (2), and Me (3), and an all alkyl species, [Zn(S2CNEt2)2]2 (4), features a centrosymmetric {ZnSCS}2 core with a step topology; both 1 and 3 were isolated as monohydrates. All compounds were broadly cytotoxic, specifically against human cancer cell lines compared with normal cells, with greater potency than cisplatin. Notably, some selectivity were indicated with 2 being the most potent against human ovarian carcinoma cells (cisA2780), and 4 being more cytotoxic toward multidrug resistant human breast carcinoma cells (MCF-7R), human colon adenocarcinoma cells (HT-29), and human lung adenocarcinoma epithelial cells (A549). Based on human apoptosis PCR-array analysis, caspase activities, DNA fragmentation, cell apoptotic assays, intracellular reactive oxygen species (ROS) measurements and human topoisomerase I inhibition, induction of apoptosis in HT-29 cells is demonstrated via both extrinsic and intrinsic pathways. Compounds 2-4 activate the p53 gene while 1 activates both p53 and p73. Cell cycle arrest at the S and G2/M phases correlates with inhibition of HT-29 cell growth. Cell invasion is also inhibited by 1-4 which is correlated with down-regulation of NF-κB.
  18. Shamsudin N, Tan AL, Wimmer FL, Young DJ, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Sep 1;71(Pt 9):1026-31.
    PMID: 26396840 DOI: 10.1107/S2056989015014280
    The asymmetric unit of the title compound, 2[Zn(C32H16N8)(C7H9N)]·3C7H9N, comprises two independent complex mol-ecules and three benzyl-amine solvent mol-ecules. Each complex mol-ecule features a penta-coordinated Zn(2+) ion within a square-pyramidal geometry, whereby the N5 donor set is defined by four atoms of the phthalocyaninate dianion (PC) and an N-bound benzyl-amine mol-ecule; it is the relative orientations of the latter that differentiate between the independent complex mol-ecules. The uncoordinated benzyl-amine mol-ecules display different conformations in the structure, with syn-Car-Car-Cm-N (ar = aromatic, m = methyl-ene) torsion angles spanning the range -28.7 (10) to 35.1 (14)°. In the crystal, N-H⋯N and N-H⋯π inter-actions lead to supra-molecular layers in the ab plane. The layers have a zigzag topology, have the coordinating and non-coordinating benzyl-amine mol-ecules directed to the inside, and present the essentially flat PC resides to the outside. This arrangement enables adjacent layers to associate via π-π inter-actions [inter-centroid distance between pyrrolyl and fused-benzene rings = 3.593 (2) Å] so that a three-dimensional architecture is formed.
  19. Caracelli I, Olivato PR, Traesel HJ, Valença J, Rodrigues DN, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Sep 01;71(Pt 9):o657-8.
    PMID: 26396889 DOI: 10.1107/S2056989015014565
    In the title β-thio-carbonyl compound, C16H16O3S, the adjacent meth-oxy and carbonyl O atoms are synperiplanar [the O-C-C-O torsion angle is 19.8 (4)°] and are separated by 2.582 (3) Å. The dihedral angle between the rings is 40.11 (16)°, and the meth-oxy group is coplanar with the benzene ring to which it is connected [the C-C-O-C torsion angle is 179.1 (3)°]. The most notable feature of the crystal packing is the formation of methine and methyl C-H⋯O(carbon-yl) inter-actions that lead to a supra-molecular chain with a zigzag topology along the c axis. Chains pack with no specific inter-molecular inter-actions between them.
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