Displaying publications 1 - 20 of 32 in total

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  1. Break MK, Tahir MI, Crouse KA, Khoo TJ
    Bioinorg Chem Appl, 2013;2013:362513.
    PMID: 24319401 DOI: 10.1155/2013/362513
    Two bidentate Schiff base ligands having nitrogen sulphur donor sequence were derived from the condensation of S-benzyldithiocarbazate (SBDTC) with 2-chloroacetophenone and 4-chloroacetophenone to give S-benzyl- β -N-(2-chlorophenyl)methylenedithiocarbazate (NS2) and S-benzyl- β -N-(4-chlorophenyl)methylenedithiocarbazate (NS4) isomers. Each of the ligands was then chelated with Cd(2+), Zn(2+), Cu(2+), and Ni(2+). The compounds were characterized via IR spectroscopy and melting point while the structure of NS4 was revealed via X-ray crystallography. Finally, the compounds were screened for antimicrobial activity to investigate the effect that is brought by the introduction of the chlorine atom to the benzene ring. X-ray crystallographic analysis showed that the structure of NS4 is planar with a phenyl ring that is nearly perpendicular to the rest of the molecules. The qualitative antimicrobial assay results showed that NS4 and its complexes lacked antifungal activity while Gram-positive bacteria were generally inhibited more strongly than Gram-negative bacteria. Furthermore, NS4 metal complexes were inhibited more strongly than the ligand while the opposite was seen with NS2 ligand and its complexes due to the partial solubility in dimethyl sulfoxide (DMSO). It was concluded that generally NS2 derivatives have higher bioactivity than that of NS4 derivatives and that the Cd complexes of both ligands have pronounced activity specifically on K. rhizophila.
  2. 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.
  3. 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.
  4. Tan YF, Break MK, Tahir MI, Khoo TJ
    Acta Crystallogr E Crystallogr Commun, 2015 Feb 1;71(Pt 2):238-40.
    PMID: 25878829 DOI: 10.1107/S205698901500095X
    The title compound, C17H18N2O2S2, synthesized via a condensation reaction between S-benzyl di-thio-carbazate and 3,4-di-meth-oxy-benzaldehyde, crystallized with two independent mol-ecules (A and B) in the asymmetric unit. Both mol-ecules have an L-shape but differ in the orientation of the benzyl ring with respect to the 3,4-di-meth-oxy-benzyl-idine ring, this dihedral angle is 65.59 (8)° in mol-ecule A and 73.10 (8)° in mol-ecule B. In the crystal, the A and B mol-ecules are linked via pairs of N-H⋯S hydrogen bonds, forming dimers with an R 2 (2)(8) ring motif. The dimers are linked via pairs of C-H⋯O hydrogen bonds, giving inversion dimers of dimers. These units are linked by C-H⋯π inter-actions, forming ribbons propagating in the [100] direction.
  5. 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.
  6. Low ML, Ravoof TB, Tahir MI, Crouse KA, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2014 Nov 1;70(Pt 11):o1207-8.
    PMID: 25484832 DOI: 10.1107/S1600536814023228
    In the title salt of an S-substituted di-thio-carbazate, C16H16N3S2 (+)·Cl(-), the dihedral angles between the almost planar (r.m.s deviation = 0.005 Å) central CN2S2 residue and the terminal pyridinium and phenyl rings are 80.09 (11) and 3.82 (11)°, respectively, indicating the cation has an L-shape; the amine H and thione S atoms are syn. The conformation about each of the imine [1.376 (3) Å] and ethene [1.333 (4) Å] bonds is E. The shortened C-C bond [1.444 (4) Å] linking the double bonds is consistent with conjugation in this part of the mol-ecule. In the crystal, supra-molecular layers with a jagged topology are formed by charged-assisted amine-H⋯Cl(-) and pyridinium-N(+)-H⋯Cl(-) hydrogen bonds. The layers stack along the a axis with no specific directional inter-actions between them.
  7. Vaneesa Nagalingam S, Wong Pik Ching J, Khaled Bin Break M, Tahir MI, Khoo TJ
    Acta Crystallogr Sect E Struct Rep Online, 2013 Dec 1;69(Pt 12):o1799-800.
    PMID: 24860292 DOI: 10.1107/S1600536813031036
    The title compound, C33H42O4 [systematic name: (1S,5S,7R)-3-benzoyl-4-hy-droxy-8,8-dimethyl-1,5,7-tris-(3-methyl-but-2--enyl)bi-cyclo-[3.3.1]nona-3-ene-2,9-dione], has a central bi-cyclo-[3.3.1]nonane-2,4,9-trione surrounded by tetra-prenyl-ated and benzoyl groups. The compound was recrystallized several times in methanol using both a slow evaporation method and with a crystal-seeding technique. This subsequently produced diffraction-quality crystals which crystallize in the ortho-rhom-bic space group P212121, in contrast to a previous report of a structure determination in the Pna21 space group [McCandlish et al. (1976 ▶). Acta Cryst. B32, 1793-1801]. The title compound has a melting point of 365-366 K, and a specific rotation [α](20) value of +51.94°. A strong intra-molecular O-H⋯O hydrogen bond is noted. In the crystal, mol-ecules are assembled in the ab plane by weak C-H⋯O inter-actions.
  8. Al-Adiwish WM, Tahir MI, Siti-Noor-Adnalizawati A, Hashim SF, Ibrahim N, Yaacob WA
    Eur J Med Chem, 2013 Jun;64:464-76.
    PMID: 23669354 DOI: 10.1016/j.ejmech.2013.04.029
    New 5-aminopyrazoles 2a-c were prepared in high yields from the reaction of known α,α-dicyanoketene-N,S-acetals 1a-c with hydrazine hydrate under reflux in ethanol. These compounds were utilized as intermediates to synthesize pyrazolo[1,5-a]-pyrimidines 3a-c, 4a-d, 5a-c, and 6a-c, as well as pyrazolo[5,1-c][1,2,4]triazines 7a-c and 8a-c, by the reaction of 2-[bis(methylthio)methylene]malononitrile, α,α-dicyanoketene-N,S-acetals 1a-b, acetylacetone, acetoacetanilide as well as acetylacetone, and malononitrile, respectively. Furthermore, cyclization of 2a-c with pentan-2,5-dione yielded the corresponding 5-pyrrolylpyrazoles 9a-c. Moreover, fusion of 2a-c with acetic anhydride resulted in the corresponding 1-acetyl-1H-pyrazoles 10a-c. The antibacterial activity and cytotoxicity against Vero cells of several selected compounds are also reported.
  9. 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.
  10. 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.
  11. 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.
  12. 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.
  13. 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].
  14. 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.
  15. Ee GC, Teo SH, Kwong HC, Mohamed Tahir MI, Silong S
    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. 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].
  17. 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.
  18. 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.
  19. 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.
  20. Break MK, Mehta S, Tahir MI, Crouse KA, Khoo TJ
    PMID: 23424463 DOI: 10.1107/S1600536812051008
    The title compound, C(12)H(16)N(2)S(3), was obtained by the condensation reaction of S-benzyl dithio-carbazate and 3-mercaptobutan-2-one. The phenyl ring and thiol (SH) group are approximately perpendicular [S-C-C-C and N-C-C-S torsion angles = 67.8 (3) and 116.9 (2)°, respectively] to the rest of the mol-ecule. In the crystal, mol-ecules are linked by weak S-H⋯S and N-H⋯S hydrogen bonds, π-π inter-actions between the benzene rings [centroid-centroid distance = 3.823 (2) Å] and C-H⋯π inter-actions.
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