Displaying publications 101 - 120 of 136 in total

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  1. Mokhtaruddin NS, Ravoof TB, Tahir MI, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Apr 1;71(Pt 4):o253-4.
    PMID: 26029441 DOI: 10.1107/S2056989015005034
    In the title hydrate, C9H12N4S·H2O (systematic name: 3-methyl-1-{(E)-[(3-methyl-pyridin-2-yl)methyl-idene]amino}-thio-urea monohydrate), a small twist is noted between the pyridine ring and the rest of the organic mol-ecule [dihedral angle = 6.96 (5)°]. The imine and pyridine N atoms are syn, and the amine H atoms are anti. The latter arrangement allows for the formation of an intra-molecular N-H⋯N(imine) hydrogen bond. Both the N-bonded H atoms form hydrogen bonds to symmetry-related water mol-ecules, and the latter forms O-H hydrogen bonds with the pyridine N and thione S atoms. These inter-actions lead to supra-molecular layers that stack along the a-axis direction with no specific inter-actions between them.
  2. Yusof EN, Ravoof TB, Tahir MI, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Apr 1;71(Pt 4):o242-3.
    PMID: 26029435 DOI: 10.1107/S2056989015004946
    In the title compound, C25H26N2O2S2, the central CN2S2 atoms are almost coplanar (r.m.s. deviation = 0.0058 Å). One phenyl ring clearly lies to one side of the central plane, while the other is oriented in the plane but splayed. Despite the different relative orientations, the phenyl rings form similar dihedral angles of 64.90 (3) and 70.06 (3)° with the central plane, and 63.28 (4)° with each other. The benzene ring is twisted with respect to the central plane, forming a dihedral angle of 13.17 (7)°. The S2C=N, N-N and N-N=C bond lengths of 1.2919 (19), 1.4037 (17) and 1.2892 (19) Å, respectively, suggest limited conjugation over these atoms; the configuration about the N-N=C bond is E. An intra-molecular O-H⋯N hydrogen bond is noted. In the crystal, phen-yl-meth-oxy C-H⋯O and phen-yl-phenyl C-H⋯π inter-actions lead to supra-molecular double chains parallel to the b axis. These are connected into a layer via meth-yl-phenyl C-H⋯π inter-actions, and layers stack along the a axis, being connected by weak π-π inter-actions between phenyl rings [inter-centroid distance = 3.9915 (9) Å] so that a three-dimensional architecture ensues.
  3. Camargo LR, Zukerman-Schpector J, Deobald AM, Braga AL, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Mar 1;71(Pt 3):o200-1.
    PMID: 25844248 DOI: 10.1107/S2056989015003242
    Two independent mol-ecules, A and B, comprise the asymmetric unit of the title compound, C20H21N3OSe. While the benzene ring directly bound to the central triazole ring is inclined to the same extent in both mol-ecules [dihedral angles = 40.41 (12) (mol-ecule A) and 44.14 (12)° (B)], greater differences are apparent in the dihedral angles between the Se-bound rings, i.e. 74.28 (12) (mol-ecule A) and 89.91 (11)° (B). Close intra-molecular Se⋯N inter-actions of 2.9311 (18) (mol-ecule A) and 2.9482 (18) Å (B) are noted. In the crystal, supra-molecular chains along the a axis are formed via O-H⋯N hydrogen bonding. These are connected into layers via C-H⋯O and C-H⋯N inter-actions; these stack along (01-1) without directional inter-molecular inter-actions between them.
  4. Zukerman-Schpector J, Caracelli I, Stefani HA, Gozhina O, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Mar 1;71(Pt 3):o179-80.
    PMID: 25844236 DOI: 10.1107/S2056989015002832
    In the title compound, C10H11BrS2, the 1,3-di-thiane ring has a chair conformation with the 1,4-disposed C atoms being above and below the remaining four atoms. The bromo-benzene ring occupies an equatorial position and forms a dihedral angle of 86.38 (12)° with the least-squares plane through the 1,3-di-thiane ring. Thus, to a first approximation the mol-ecule has mirror symmetry with the mirror containing the bromo-benzene ring and the 1,4-disposed C atoms of the 1,3-di-thiane ring. In the crystal, mol-ecules associate via weak methyl-ene-bromo-benzene C-H⋯π and π-π [Cg⋯Cg = 3.7770 (14) Å for centrosymmetrically related bromo-benzene rings] inter-actions, forming supra-molecular layers parallel to [10-1]; these stack with no specific inter-molecular inter-actions between them.
  5. Siddiqui R, Abjani F, Yeo CI, Tiekink ER, Khan NA
    J Negat Results Biomed, 2017 Apr 03;16(1):6.
    PMID: 28366172 DOI: 10.1186/s12952-017-0070-7
    BACKGROUND: Gold compounds have shown promise in the treatment of non-communicable diseases such as rheumatoid arthritis and cancer, and are considered of value as anti-microbial agents against Gram-negative and Gram-positive bacteria, and have anti-parasitic properties against Schistosoma mansoni, Trypanosoma brucei, Plasmodium falciparum, Leishmania infantinum, Giardia lamblia, and Entamoeba histolytica. They are known to affect enzymatic activities that are required for the cellular respiration processes.

    METHODS: Anti-amoebic effects of phosphanegold(I) thiolates were tested against clinical isolate of A. castellanii belonging to the T4 genotype by employing viability assays, growth inhibition assays, encystation assays, excystation assays, and zymographic assays.

    RESULTS: The treatment of A. castellanii with the phosphanegold(I) thiolates tested (i) had no effect on the viability of A. castellanii as determined by Trypan blue exclusion test, (ii) did not affect amoebae growth using PYG growth medium, (iii) did not inhibit cellular differentiation, and (iv) had no effect on the extracellular proteolytic activities of A. castellanii.

    CONCLUSION: Being free-living amoeba, A. castellanii is a versatile respirator and possesses respiratory mechanisms that adapt to various aerobic and anaerobic environments to avoid toxic threats and adverse conditions. For the first time, our findings showed that A. castellanii exhibits resistance to the toxic effects of gold compounds and could prove to be an attractive model to study mechanisms of metal resistance in eukaryotic cells.

  6. Tan SL, Yeo CI, Heard PJ, Akien GR, Halcovitch NR, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Dec 01;72(Pt 12):1799-1805.
    PMID: 27980834
    The title compound, [Cu(C5H5NO2S2)(C18H15P)2]·CHCl3, features a tetra-hedrally coordinated CuI atom within a P2S2 donor set defined by two phosphane P atoms and by two S atoms derived from a symmetrically coordinating di-thio-carbamate ligand. Both intra- and inter-molecular hy-droxy-O-H⋯O(hydroxy) hydrogen bonding is observed: the former closes an eight-membered {⋯HOC2NC2O} ring, whereas the latter connects centrosymmetrically related mol-ecules into dimeric aggregates via eight-membered {⋯H-O⋯H-O}2 synthons. The complex mol-ecules are arranged to form channels along the c axis in which reside the chloro-form mol-ecules, being connected by Cl⋯π(arene) and short S⋯Cl [3.3488 (9) Å] inter-actions. The inter-molecular inter-actions have been investigated further by Hirshfeld surface analysis, which shows the conventional hydrogen bonding to be very localized with the main contributors to the surface, at nearly 60%, being H⋯H contacts. Solution NMR studies indicate that whilst the same basic mol-ecular structure is retained in solution, the tri-phenyl-phosphane ligands are highly labile, exchanging rapidly with free Ph3P at room temperature.
  7. Caracelli I, Maganhi SH, Moran PJ, de Paula BR, Delling FN, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Sep 01;70(Pt 9):o1051-2.
    PMID: 25309220 DOI: 10.1107/S1600536814018819
    In the title compound, C17H14N2O6, the conformation about the C=C double bond [1.345 (2) Å] is E, with the ketone moiety almost coplanar [C-C-C-C torsion angle = 9.5 (2)°] along with the phenyl ring [C-C-C-C = 5.9 (2)°]. The aromatic rings are almost perpendicular to each other [dihedral angle = 86.66 (7)°]. The 4-nitro moiety is approximately coplanar with the benzene ring to which it is attached [O-N-C-C = 4.2 (2)°], whereas the one in the ortho position is twisted [O-N-C-C = 138.28 (13)°]. The mol-ecules associate via C-H⋯O inter-actions, involving both O atoms from the 2-nitro group, to form a helical supra-molecular chain along [010]. Nitro-nitro N⋯O inter-actions [2.8461 (19) Å] connect the chains into layers that stack along [001].
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
  15. 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.
  16. 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.
  17. Caracelli I, Zukerman-Schpector J, Stefani HA, Gozhina O, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Mar 01;71(Pt 3):o181-2.
    PMID: 25844237 DOI: 10.1107/S2056989015002844
    In the title compound, C10H11NO2S2, the 1,3-di-thiane ring has a chair conformation with the 1,4-disposed C atoms being above and below the remaining four atoms. The nitro-benzene substituent occupies an equatorial position and forms a dihedral angle of 88.28 (5)° with the least-squares plane through the 1,3-di-thiane ring. The nitro group is twisted out of the plane of the benzene ring to which it is connected, forming a dihedral angle of 10.12 (3)°. In the crystal, mol-ecules aggregate into supra-molecular zigzag chains (glide symmetry along the c axis) via nitro-benzene N-O⋯π [N-O⋯Cg(benzene) = 3.4279 (18) Å and angle at O = 93.95 (11)°] inter-actions. The chains pack with no specific inter-molecular inter-actions between them.
  18. Camargo LR, Zukerman-Schpector J, Deobald AM, Braga AL, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Mar 01;71(Pt 3):o202-3.
    PMID: 25844249 DOI: 10.1107/S2056989015003230
    In the title compound, C21H17N3OSe, the dihedral angles between the central five-membered ring and the C- and N-bound rings are 17.89 (10) and 42.35 (10)°, respectively, indicating the mol-ecule is twisted. The dihedral angle between the Se-bound rings is 85.36 (10)°. A close intra-molecular Se⋯O contact of 2.8507 (13) Å is noted. In the crystal, C-H⋯O, C-H⋯N and C-H⋯π inter-actions lead to the formation of supra-molecular layers parallel to (011); these stack with no specific inter-molecular inter-actions between them.
  19. Camargo LR, Zukerman-Schpector J, Deobald AM, Braga AL, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Mar 01;71(Pt 3):o204-5.
    PMID: 25844250 DOI: 10.1107/S2056989015003229
    In the title compound, C23H21N3Se, the C-bound phenyl ring is almost coplanar with the central five-membered ring [dihedral angle = 2.84 (10)°], but the N-bound benzene ring is inclined [dihedral angle = 47.52 (10)°]. The dihedral angle between the Se-bound rings is 69.24 (9)°. An intra-molecular Se⋯N inter-action of 3.0248 (15) Å is noted. In the crystal, C-H⋯π inter-actions connect mol-ecules into double layers that stack along the a axis with no directional inter-actions between them.
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