Displaying all 17 publications

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  1. Kwong HC, Rahman MZ, Mohamed Tahir MI, Silong S
    PMID: 22220018 DOI: 10.1107/S1600536811041602
    In the title compound, C(19)H(29)NO, the C-C and C-N bond distances of the benzonitrile group are 1.445 (2) and 1.157 (2) Å, respectively. The aliphatic fragment adopts a bent zigzag arangement which differs from the planar zigzag arrangement normally observed in n-alkanes or long-chain alkyl-benzenes. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds occur. A C-H⋯N inter-action also occurs. In the crystal, mol-ecules are packed with the nitrile and aliphatic groups oriented in a head-to-tail fashion involving, forming a ripple-like motif along the a axis.
  2. Kwong HC, Rahman MZ, Mohamed Tahir MI, Silong S
    Acta Crystallogr Sect E Struct Rep Online, 2011 Feb 12;67(Pt 3):o612.
    PMID: 21522369 DOI: 10.1107/S1600536811003096
    In the title compound, C(13)H(19)NO(2), the dihedral angle between the benzene ring and the plane throught the non-H atoms of the amide group is 29.3 (1)°. The benzene ring and the alkane carbon skeleton plane are twisted slightly with respect to each other [5.40 (5)°]. In the crystal, mol-ecules are oriented with the amide groups head-to-head, forming N-H⋯O hydrogen-bonded dimers. The dimers are connected by further N-H⋯O hydrogen bonds into a ladder-like motif along the b axis.
  3. Mahmod II, Kwong HC, Mohamed Tahir MI, Ismail IS
    Acta Crystallogr Sect E Struct Rep Online, 2011 Dec 01;67(Pt 12):o3296.
    PMID: 22199798 DOI: 10.1107/S1600536811047337
    The title dammarane triterpenoid, C(30)H(50)O(4), assigned the name chrysura, was isolated from an ethyl acetate extract of Walsura chrysogyne leaves (Meliaceae). It has 20S*,24S* relative stereochemistry and an oxepanone ring with two methyl groups at position 4. The two cyclo-hexane rings adopt chair conformations. The cyclo-pentane and tetra-hydro-furan rings have envelope conformations; their mean planes make a dihedral angle of 13.1 (3)°, indicating that the rings are only slightly tilted with respect to each other. There is an intra-molecular C-H⋯O hydrogen bond in the mol-ecule, which forms S(6) and S(7) ring motifs. In the crystal, mol-ecules are linked via O-H⋯O and C-H⋯O hydrogen bonds, forming chains propagating along [001] which stack along the b-axis direction.
  4. Ravoof TB, Omar SA, Mohamed Tahir MI, Crouse KA
    Acta Crystallogr Sect E Struct Rep Online, 2012 May 1;68(Pt 5):m534-5.
    PMID: 22590061 DOI: 10.1107/S1600536812013529
    The title compound, [Zn(C(15)H(14)N(3)S(2))(2)], contains two chemically equivalent Schiff base anions that are coordinated to the Zn(II) ion as tridentate N,N',S-chelating ligands, creating a distorted octa-hedral environment [the smallest angle being 75.40 (6)° and the widest angle being 162.87 (6)°], with the two S atoms in cis positions. The dihedral angle between the mean planes of the two coordinating ligands is 85.65 (5)°. Weak C-H⋯S hydrogen bonds are also observed.
  5. Ravoof TB, Omar SA, Mohamed Tahir MI, Crouse KA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Apr 1;68(Pt 4):m390-1.
    PMID: 22589778 DOI: 10.1107/S1600536812009592
    In the title compound, [Zn(C(20)H(16)N(3)S(2))(2)]·CH(3)CN, two different Schiff base moieties coordinate to the central Zn(II) ion as tridentate N,N',S-chelating ligands, creating a distorted octa-hedral environment [the smallest angle being 73.24 (6)° and the widest angle being 155.73 (7)°], with the two S atoms in cis positions. The dihedral angle between the mean planes of the two coordinating ligands is 83.65 (5)°. The crystal packing is consolidated by weak C-H⋯N hydrogen-bonding inter-actions.
  6. Omar SA, Ravoof TB, Mohamed Tahir MI, Crouse KA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Mar 1;68(Pt 3):m316-7.
    PMID: 22412456 DOI: 10.1107/S1600536812006952
    The structure of the title compound, [Ni(C(15)H(14)N(3)S(2))(2)]·H(2)O, has one mol-ecule in the asymmetric unit, along with a solvent water mol-ecule. The two different Schiff base moieties coordinate to the central Ni(II) ion as tridentate N,N',S-chelating ligands, creating a six-coordinate distorted octa-hedral environment [the smallest angle being 77.43 (7)° and the widest angle being 169.99 (7)°]. The mean planes of the two ligands are nearly orthogonal to each other with an angle of 89.53 (6)°. The packing of the complex is supported by O-H⋯N and O-H⋯S hydrogen bonding between the solvent water mol-ecule and the uncoordinated N and S atoms of neighbouring ligands.
  7. Rahman ML, Kwong HC, Mohd Yusoff M, Hegde G, Mohamed Tahir MI, Rahman MZ
    Acta Crystallogr Sect E Struct Rep Online, 2012 Oct 1;68(Pt 10):o2958.
    PMID: 23125741 DOI: 10.1107/S1600536812038718
    The title compound, C(17)H(16)N(2)O(3), has an E conformation about the azobenzene (-N=N-) linkage. The benzene rings are twisted slightly with respect to each other [6.79 (9)°], while the dihedral angle between the plane through the carb-oxy group and the attached benzene ring is 3.2 (2)°. In the crystal, mol-ecules are oriented with the carb-oxy groups head-to-head, forming O-H⋯O hydrogen-bonded inversion dimers. These dimers are connected by C-H⋯O hydrogen-bonds into layers lying parallel to the (013) plane.
  8. Ee GC, Mah SH, Kwong HC, Teh SS, Mohamed Tahir MI, Silong S
    Acta Crystallogr Sect E Struct Rep Online, 2011 Oct 1;67(Pt 10):o2607-8.
    PMID: 22064829 DOI: 10.1107/S1600536811036294
    THE TITLE COMPOUND [SYSTEMATIC NAME: 5,10-di-hy-droxy-2,2-di-methyl-12-(2-methyl-but-3-en-2-yl)-pyrano[3,2-b]xanthen-6(2H)-one], C(23)H(22)O(5), isolated from the stem bark of Calophyllum soulattri, consists of four six-membered rings and a 2-methyl-but-3-en-2-yl side chain. The tricyclic xanthone ring system is almost planar [maximum deviation = 0.093 (2) Å], whereas the pyran-oid ring is in a distorted boat conformation. The 2-methyl-but-3-en-2-yl side chain is in a synperiplanar conformation. There are two intra-molecular O-H⋯O hydrogen bonds. In the crystal, mol-ecules are linked by C-H⋯O inter-actions, forming a zigzag chain propagating in [010].
  9. Ee GC, Sim WC, Kwong HC, Mohamed Tahir MI, Silong S
    PMID: 21589631 DOI: 10.1107/S1600536810049123
    The title compound (trivial name α-mangostin), C(24)H(26)O(6), isolated from Cratoxylum glaucum, is characterized by a xanthone skeleton of three fused six-membered rings and two 3-methyl-but-2-enyl side chains. The three rings in the structure are nearly coplanar, with an r.m.s. deviation for the tricyclic ring system of 0.0014 Å. The two 3-methyl-but-2-enyl side chains are in (+)-synclinal and (-)-anti-clinal conformations. Intra-molecular O-H⋯O and C-H⋯O inter-actions occur. The crystal structure is stabilized by inter-molecular O-H⋯O, C-H⋯O and C-H⋯π inter-actions.
  10. Rahman ML, Kwong HC, Mohd Yusoff M, Hegde G, Mohamed Tahir MI
    Acta Crystallogr Sect E Struct Rep Online, 2012 Dec 1;68(Pt 12):o3311-2.
    PMID: 23476157 DOI: 10.1107/S160053681204559X
    In the title compound, C26H24N2O2, the benzimidazole ring system is almost planar [maximum displacement = 0.025 (1) Å] and makes dihedral angles of 80.48 (5) and 41.57 (5)° with the benzene rings, which are inclined to one another by 65.33 (6)°. In the crystal, mol-ecules are linked via C-H⋯π and weak π-π inter-actions [centroid-centroid distance = 3.8070 (7) Å and inter-planar distance = 3.6160 (5) Å].
  11. Tayamon S, Mazlan NA, Ravoof TB, Mohamed Tahir MI, Crouse KA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Nov 1;68(Pt 11):o3104-5.
    PMID: 23284431 DOI: 10.1107/S1600536812042018
    The title compound C(8)H(15)N(3)S has two mol-ecules in the asymmetric unit in which cis-trans isomerism is exhibited around the N(NH)C=S bonds. The cyclo-hexyl rings in both mol-ecules adopt a chair conformation. In the crystal, N-H⋯S hydrogen bonding produces dimers, which are inter-connected through further N-H⋯S hydrogen bonds, forming chains along the b-axis direction.
  12. Maryam M, Tan SL, Crouse KA, Mohamed Tahir MI, Chee HY
    Turk J Chem, 2020;44(5):1395-1409.
    PMID: 33488239 DOI: 10.3906/kim-2006-22
    A series of Schiff bases have been successfully synthesized through the acid-catalyzed condensation of S-substituted dithiocarbazates and three enantiomerically pure monoterpenes, (1 R )-(+)-camphor, (1 S )-(-)-camphor, (1 R )-(-)-camphorquinone, (1 S )-(+)-camphorquinone, ( R )-(-)-carvone and ( S )-(+)-carvone. Spectroscopic results revealed that the Schiff bases containing camphor or carvone likely adopted an E -configuration along the characteristic imine bond while those containing camphorquinone assumed a Z -configuration. The antidengue potential of these compounds was evaluated based on DENV 2 caused cytopathic effect (CPE) reduction-based in vitro evaluation. The compounds were validated through secondary foci forming unit reduction assay (FFURA). Compounds were also tested for their cytotoxicity against Vero cells. The compounds showed variable degrees of antiviral activity with the camphor compounds displaying the highest antidengue potential. The enantiomers of the compounds behaved almost similarly during the antiviral evaluation.
  13. Arif Tawfeeq N, Kwong HC, Mohamed Tahir MI, Ravoof TBSA
    Acta Crystallogr E Crystallogr Commun, 2019 Nov 01;75(Pt 11):1613-1619.
    PMID: 31709078 DOI: 10.1107/S2056989019013458
    In the title hydrazinecarbodi-thio-ate derivative, C27H26N2O2S2, the asymmetric unit is comprised of four mol-ecules (Z = 8 and Z' = 4). The 4-meth-oxy-phenyl rings are slightly twisted away from their attached olefinic double bonds [torsion angles = 5.9 (4)-19.6 (4)°]. The azomethine double bond has an s-trans configuration relative to one of the C=C bonds and an s-cis configuration relative to the other [C=C-C= N = 147.4 (6)-175.7 (2) and 15.3 (3)-37.4 (7)°, respectively]. The torsion angles between the azomethine C=N double bond and hydrazine-1-carbodi-thio-ate moiety indicate only small deviations from planarity, with torsion angles ranging from 0.9 (3) to 6.9 (3)° and from 174.9 (3) to 179.7 (2)°, respectively. The benzyl ring and the methyl-enesulfanyl moiety are almost perpendicular to each other, as indicated by their torsion angles [range 93.7 (3)-114.6 (2)°]. In the crystal, mol-ecules are linked by C-H⋯O, N-H⋯S and C-H⋯π(ring) hydrogen-bonding inter-actions into a three-dimensional network. Structural details of related benzyl hydrazine-1-carbodi-thio-ate are surveyed and compared with those of the title compound.
  14. Ravoof TB, Omar SA, Mohamed Tahir MI, Crouse KA
    Acta Crystallogr Sect E Struct Rep Online, 2012 May 01;68(Pt 5):m664.
    PMID: 22590148 DOI: 10.1107/S1600536812017333
    The asymmetric unit of the title compound, [Ni(C(15)H(14)N(3)S(2))(2)], consists of two independent mol-ecules with similar configurations. Each Ni(2+) cation is coordinated in a cis-mode by two tridentate N,N',S-chelating Schiff base ligands, creating a distorted octa-hedron [the smallest angle being 77.57 (7)° and the widest being 168.97 (7)° for one mol-ecule, and 78.04 (7) and 167.55 (7)° for the second mol-ecule]. The dihedral angle between the mean coordination planes of the two ligands is 86.76 (7)° for one and 89.99 (7)° for the second mol-ecule. π-π inter-actions between neighbouring pyridine rings with plane-to-plane distances of 3.540 (1) and 3.704 (1) Å are observed.
  15. Ee GC, Teo SH, Kwong HC, Mohamed Tahir MI, Silong S
    Acta Crystallogr Sect E Struct Rep Online, 2010 Nov 27;66(Pt 12):o3331-2.
    PMID: 21589606 DOI: 10.1107/S1600536810048592
    The title compound, Artonol B, C(24)H(20)O(7), isolated from the stem bark of Artocarpus kemando, consists of four six-membered rings and one five-membered ring. The tricyclic xanthone ring system is almost planar [maximum deviation 0.115 (5) Å], whereas the pyran-oid ring is in a distorted boat conformation·The furan ring is almost coplanar with the fused aromatic ring, making a dihedral angle of 3.76 (9)°. The phenol ring serves as a intra-molecular hydrogen-bond donor to the adjacent carbonyl group and also acts as an inter-molecular hydrogen-bond acceptor for the methyl groups of adjacent mol-ecules, forming a three-dimensional network in the crystal.
  16. Arif Tawfeeq N, Kwong HC, Mohamed Tahir MI, Ravoof TBSA
    Acta Crystallogr E Crystallogr Commun, 2019 Jun 01;75(Pt 6):774-779.
    PMID: 31391964 DOI: 10.1107/S2056989019006480
    In the title bis-chalcone, C17H12Br2O, the olefinic double bonds are almost coplanar with their attached 4-bromo-phenyl rings [torsion angles = -10.2 (4) and -6.2 (4)°], while the carbonyl double bond is in an s-trans conformation with with respect to one of the C=C bonds and an s-cis conformation with respect to the other [C=C-C=O = 160.7 (3) and -15.2 (4)°, respectively]. The dihedral angle between the 4-bromo-phenyl rings is 51.56 (2)°. In the crystal, mol-ecules are linked into a zigzag chain propagating along [001] by weak C-H⋯π inter-actions. The conformations of related bis-chalcones are surveyed and a Hirshfeld surface analysis is used to investigate and qu-antify the inter-molecular contacts.
  17. Md Yusof EN, S A Ravoof TB, Tiekink ER, Veerakumarasivam A, Crouse KA, Mohamed Tahir MI, et al.
    Int J Mol Sci, 2015 May 15;16(5):11034-54.
    PMID: 25988384 DOI: 10.3390/ijms160511034
    Two bidentate NS ligands were synthesized by the condensation reaction of S-2-methylbenzyldithiocarbazate (S2MBDTC) with 2-methoxybenzaldehyde (2MB) and 3-methoxybenzaldehyde (3MB). The ligands were reacted separately with acetates of Cu(II), Ni(II) and Zn(II) yielding 1:2 (metal:ligand) complexes. The metal complexes formed were expected to have a general formula of [M(NS)2] where M = Cu2+, Ni2+, and Zn2+. These compounds were characterized by elemental analysis, molar conductivity, magnetic susceptibility and various spectroscopic techniques. The magnetic susceptibility measurements and spectral results supported the predicted coordination geometry in which the Schiff bases behaved as bidentate NS donor ligands coordinating via the azomethine nitrogen and thiolate sulfur. The molecular structures of the isomeric S2M2MBH (1) and S2M3MBH (2) were established by X-ray crystallography to have very similar l-shaped structures. The Schiff bases and their metal complexes were evaluated for their biological activities against estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) breast cancer cell lines. Only the Cu(II) complexes showed marked cytotoxicity against the cancer cell lines. Both Schiff bases and other metal complexes were found to be inactive. In concordance with the cytotoxicity studies, the DNA binding studies indicated that Cu(II) complexes have a strong DNA binding affinity.
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