Displaying publications 1 - 20 of 136 in total

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  1. Basu Baul TS, Longkumer I, Ng SW, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Nov 6;69(Pt 12):m633-4.
    PMID: 24454154 DOI: 10.1107/S1600536813029693
    The title dimethyl sulfoxide solvate, [Hg2(C12H9ClN2)I2]·C2H6OS, features tetra-hedrally and linearly coordinated Hg(II) atoms. The distorted tetrahedral coordination sphere is defined by chelating N atoms that define an acute angle [69.6 (3)°] and two I atoms that form a wide angle [142.80 (4)°]. The linearly coordinated Hg(II) atom [177.0 (4)°] exists with a donor set defined by C and Cl atoms. Secondary inter-actions are apparent in the crystal packing with the tetra-hedrally and linearly coordinated Hg(II) atoms expanding their coordination environments by forming weak Hg⋯I [3.772 (7) Å] and Hg⋯O [2.921 (12) Å] inter-actions, respectively. Mercury-containing mol-ecules stack along the a axis, are connected by π-π inter-actions [inter-centroid distance between pyridine and benzene rings = 3.772 (7) Å] and define channels in which the dimethyl sulfoxide mol-ecules reside. The latter are connected by the aforementioned Hg⋯O inter-actions as well as C-H⋯I and C-H⋯O inter-actions, resulting in a three-dimensional architecture.
  2. 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.
  3. 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.
  4. Lee SL, Tan AL, Young DJ, Jotani MM, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Jun 1;72(Pt 6):849-53.
    PMID: 27308057 DOI: 10.1107/S205698901600832X
    The title compound, C13H10N2O2 [also called 1-(pyridin-2-yl)-3-(pyridin-3-yl)propane-1,3-dione], features an almost planar (r.m.s. deviation = 0.0095 Å) central C3O2 core consolidated by an intra-molecular hy-droxy-O-H⋯O(carbon-yl) hydrogen bond. Twists are evident in the mol-ecule, as seen in the dihedral angles between the central core and the 2- and pyridin-3-yl rings of 8.91 (7) and 15.88 (6)°, respectively. The conformation about the C=C bond [1.3931 (17) Å] is Z, and the N atoms lie to the same side of the mol-ecule. In the mol-ecular packing, supra-molecular chains along the a axis are mediated by π(pyridin-2-yl)-π(pyridin-3-yl) inter-actions [inter-centroid distance = 3.7662 (9) Å]. The observation that chains pack with no directional inter-actions between them is consistent with the calculated electrostatic potential, which indicates that repulsive inter-actions dominate.
  5. Al-Mehana WN, Shakir RM, Yahya R, Abd Halim SN, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2011 Jul 1;67(Pt 7):o1659.
    PMID: 21837059 DOI: 10.1107/S1600536811022410
    The complete mol-ecule in the title compound, C(22)H(20)N(2)O(4), is generated by the application of an inversion centre. With the exception of the terminal acetyl-ene groups [C-O-C-C = -78.02 (17)°], the remaining atoms constituting the mol-ecule are essentially coplanar. The configuration around the C=N bond [1.282 (2) Å] is E. The formation of supra-molecular chains mediated by C-H⋯O inter-actions, occurring between methyl-ene H and meth-oxy O atoms, is the most notable feature of the crystal packing.
  6. Low ML, Ravoof TB, Tahir MI, Crouse KA, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2013 Feb 1;69(Pt 2):o167-8.
    PMID: 23424455 DOI: 10.1107/S1600536812051537
    In the title compound, C(16)H(15)N(3)S(2), the central C(2)N(2)S(2) residue is planar (r.m.s. deviation = 0.045 Å) and the pyridyl and benzene rings are inclined and approximately coplanar to this plane, respectively [dihedral angles = 72.85 (9) and 10.73 (9)°], so that, overall, the mol-ecule adopts an L-shape. The conformation about each of the N=C [1.290 (3) Å] and C=C [1.340 (3) Å] bonds is E. Supra-molecular chains along [1-10] are stabilized by N-H⋯N(pyridine) hydrogen bonding and these are connected into a double layer that stacks along the c-axis direction by C-H⋯π(pyridine) inter-actions.
  7. Lee SM, Lo KM, Tan SL, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Oct 1;72(Pt 10):1390-1395.
    PMID: 27746926
    The Yb(III) atom in the title complex, [Yb(C27H24Cl3N4O3)] [systematic name: (2,2',2''-{(nitrilo)-tris-[ethane-2,1-di-yl(nitrilo)-methylyl-idene]}tris-(4-chloro-phenolato)ytterbium(III)], is coordinated by a trinegative, hepta-dentate ligand and exists within an N4O3 donor set, which defines a capped octa-hedral geometry whereby the amine N atom caps the triangular face defined by the three imine N atoms. The packing features supra-molecular layers that stack along the a axis, sustained by a combination of aryl-C-H⋯O, imine-C-H⋯O, methyl-ene-C-H⋯π(ar-yl) and end-on C-Cl⋯π(ar-yl) inter-actions. A Hirshfeld surface analysis points to the major contributions of C⋯H/ H⋯C and Cl⋯H/H⋯Cl inter-actions (along with H⋯H) to the overall surface but the Cl⋯H contacts are at distances greater than the sum of their van der Waals radii.
  8. Yeo CI, Tiekink ER
    PMID: 22219989 DOI: 10.1107/S1600536811041894
    The title compound, C(13)H(10)Cl(2)N(2)S, represents a monoclinic polymorph of the previously reported ortho-rhom-bic form [Ramnathan et al. (1996 ▶). Acta Cryst. C52, 134-136]. The mol-ecule is twisted with the dihedral angle between the benzene rings being 55.37 (7)°. The N-H atoms are syn to each other, which contrasts their anti disposition in the ortho-rhom-bic form. In the crystal, mol-ecules assemble into zigzag chains along the c axis via N-H⋯S hydrogen bonds. Chains are connected into layers via C-H⋯Cl inter-actions, and these stack along the a axis.
  9. 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.
  10. 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.
  11. 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.
  12. Ketuly KA, Hadi AH, Ng SW, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2011 May 1;67(Pt 5):o1160-1.
    PMID: 21754468 DOI: 10.1107/S1600536811013651
    Three independent mol-ecules of the title estrone derivative and a mol-ecule of methanol comprise the asymmetric unit of the title compound [systematic name: 13-methyl-6,7,8,9,11,12,13,14,15,16-deca-hydro-cyclo-penta-[a]phenanthren-3-ol-meth-an-ol (3/1)], 3C(18)H(24)O·CH(3)OH. Two of the estrone mol-ecules exhibit 50:50 disorder (one displays whole-mol-ecule disorder and the other partial disorder in the fused five- and six-membered rings) so that five (partial) mol-ecular conformations are discernable. The conformation of the six-membered ring abutting the aromatic ring is close to a half-chair in all five components. The conformation of the six-membered ring fused to the five-membered ring is based on a chair with varying degrees of distortion ranging from minor to significant. Two distinct conformations are found for the five-membered ring: in four mol-ecules, the five-membered ring is twisted about the bond linking it to the six-membered ring, and in the other, the five-membered ring is an envelope with the quaternary C atom being the flap atom. The crystal packing features O-H⋯O hydrogen bonding whereby the four mol-ecules comprising the asymmetric unit are linked into a supra-molecular chain along the b axis.
  13. Tayamon S, Ravoof TB, Tahir MI, Crouse KA, Tiekink ER
    PMID: 23476568 DOI: 10.1107/S1600536813003966
    In the title salt, C14H17N2(+)·Cl(-), the central N atom is pyramidal (sum of bond angles = 330.9°) and there is a near orthogonal relationship between the benzene rings [dihedral angle = 89.95 (10)°]. The crystal packing features N-H⋯Cl hydrogen bonds, which lead to a supra-molecular undulating ribbon along the a axis comprising edge-shared eight-membered {⋯HNH⋯Cl}2 synthons. The chains are connected into layers in the ab plane by C-H⋯π inter-actions.
  14. 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].
  15. Nasir SB, Abdullah Z, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588464 DOI: 10.1107/S160053681003014X
    In the title compound, C(11)H(10)N(2)O(2), the benzene ring faces towards one of the pyrimidine N atoms, and is almost orthogonal to the plane through the pyrimidine ring [dihedral angle = 84.40 (14)°]. In the crystal, the presence of C-H⋯π and π-π [centroid-centroid separation = 3.7658 (18) Å] inter-actions leads to a supra-molecular array in the ac plane. The layers thus formed inter-digitate along the b axis.
  16. Hassan ND, Abdullah Z, Tajuddin HA, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588753 DOI: 10.1107/S1600536810034100
    In the title mol-ecule, C(14)H(9)N(3)O(3), the dihedral angle between the quinoxaline and benzene rings is 77.13 (9)°. The mol-ecule is twisted about the ether-benzene O-C bond, with a C-O-C-C torsion angle of -102.8 (2)°. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming layers in the ab plane, with one nitro O atom accepting two such inter-actions. The layers stack along the c-axis direction via weak C-H⋯π inter-actions.
  17. Nasir SB, Abdullah Z, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588752 DOI: 10.1107/S1600536810034057
    In the title mol-ecule, C(12)H(10)N(2)O(4), the pyridine and benzene rings are almost orthogonal [dihedral angle = 86.69 (11)°], with the pyridine N atom directed towards the centre of the benzene ring. The -NO(2) [O-N-C-C = -26.1 (3)°] and -OMe [C-O-C-C = 166.5 (2)°] substituents are not coplanar with their respective aromatic rings. In the crystal, supra-molecular layers in the ab plane are formed via C-H⋯π inter-actions involving methyl H atoms and the pyridine and benzene rings. Short N-O⋯π contacts (where the π-system is derived from the pyridine ring) occur between layers in the c-axis direction.
  18. Nasir SB, Abdullah Z, Mainal A, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588653 DOI: 10.1107/S1600536810031946
    In the title compound, C(11)H(10)N(2)O(2), the aromatic rings are almost orthogonal to each other [dihedral angle = 86.97 (8)°], with the benzene ring orientated to face one of the pyrazine N atoms. In the crystal, centrosymmetrically related pairs are connected via pairs of C-H⋯π inter-actions and the dimeric units thus formed pack into undulating layers that stack along the a axis.
  19. Nasir SB, Abdullah Z, Fairuz ZA, Ng SW, Tiekink ER
    PMID: 21588583 DOI: 10.1107/S1600536810030448
    The pyrimidine and benzene rings in the title compound, C(10)H(8)N(2)O(2), form a dihedral angle of 71.03 (7)°, with the roughly orthogonal benzene ring being folded towards one of the pyrimidine N atoms. In the crystal, pairs of O-H⋯N hydrogen bonds connect mol-ecules related by twofold symmetry into dimeric aggregates. These associate into a supra-molecular chain propagating along the b axis by way of C-H⋯π contacts. The chains are cross-linked by π-π inter-actions that occur between pyrimidine rings [ring centroid-centroid distances = 3.5393 (9) and 3.5697 (9) Å].
  20. 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.
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