Displaying publications 61 - 80 of 99 in total

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  1. Al-Wabli RI, El-Emam AA, Alroqi OS, Chidan Kumar CS, Fun HK
    Acta Crystallogr E Crystallogr Commun, 2015 Feb 1;71(Pt 2):o115-6.
    PMID: 25878859 DOI: 10.1107/S2056989015000596
    The title compound, C18H20ClN3S, is a functionalized triazoline-3-thione derivative. The benzene ring is almost perpendic-ular to the planar 1,2,4-triazole ring [maximum deviation = 0.007 (1) Å] with a dihedral angle of 89.61 (5)° between them and there is an adamantane substituent at the 3-position of the triazole-thione ring. In the crystal, N-H⋯S hydrogen-bonding inter-actions link the mol-ecules into chains extending along the c-axis direction. The crystal packing is further stabilized by weak C-H⋯π inter-actions that link adjacent chains into a two-dimensional structure in the bc plane. The crystal studied was an inversion twin with a 0.50 (3):0.50 (3) domain ratio.
    Matched MeSH terms: Heterocyclic Compounds
  2. Mohamad R, Awang N, Jotani MM, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Aug 1;72(Pt 8):1130-7.
    PMID: 27536397 DOI: 10.1107/S2056989016011385
    The crystal and mol-ecular structures of two di-phenyl-tin bis-(di-thio-carbamate)s, [Sn(C6H5)2(C5H10NOS2)2], (I), and [Sn(C6H5)2(C7H14NO2S2)2], (II), are described. In (I), in which the metal atom lies on a twofold rotation axis, the di-thio-carbamate ligand coordinates with approximately equal Sn-S bond lengths and the ipso-C atoms of the Sn-bound phenyl groups occupy cis-positions in the resulting octa-hedral C2S4 donor set. A quite distinct coordination geometry is noted in (II), arising as a result of quite disparate Sn-S bond lengths. Here, the four S-donors define a trapezoidal plane with the ipso-C atoms lying over the weaker of the Sn-S bonds so that the C2S4 donor set defines a skewed trapezoidal bipyramid. The packing of (I) features supra-molecular layers in the ab plane sustained by methyl-ene-C-H⋯π(Sn-ar-yl) inter-actions; these stack along the c-axis direction with no specific inter-actions between them. In (II), supra-molecular chains along the b-axis direction are formed by methyl-ene-C-O(ether) inter-actions; these pack with no directional inter-actions between them. A Hirshfeld surface analysis was conducted on both (I) and (II) and revealed the dominance of H⋯H inter-actions contributing to the respective surfaces, i.e. >60% in each case, and other features consistent with the description of the mol-ecular packing above.
    Matched MeSH terms: Heterocyclic Compounds
  3. 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.
    Matched MeSH terms: Heterocyclic Compounds
  4. Suresh Kumar R, Ashraf Ali M, Osman H, Ismail R, Choon TS, Yoon YK, et al.
    Bioorg Med Chem Lett, 2011 Jul 1;21(13):3997-4000.
    PMID: 21621414 DOI: 10.1016/j.bmcl.2011.05.003
    Hexacyclic derivatives share vital pharmacological properties, considered useful in Alzheimer's disease. The aim of this study was synthesis and its evaluation for acetyl cholinesterase inhibitory activity of novel hexacyclic analogues. Compound 4f, showed potent inhibitory activity against acetyl cholinesterase enzyme with IC(50) 0.72 μmol/L.
    Matched MeSH terms: Heterocyclic Compounds with 4 or More Rings/chemical synthesis*; Heterocyclic Compounds with 4 or More Rings/pharmacology; Heterocyclic Compounds with 4 or More Rings/chemistry
  5. Faridnia F, Hussin AS, Saari N, Mustafa S, Yee LY, Manap MY
    Benef Microbes, 2010 Jun;1(2):149-54.
    PMID: 21831754 DOI: 10.3920/BM2009.0035
    Consumption of probiotics has been associated with decreased risk of colon cancer and reported to have antimutagenic/ anti-carcinogenic properties. One possible mechanism for this effect involves physical binding of the mutagenic compounds, such as heterocyclic amines (HCAs), to the bacteria. Therefore, the objective of this study was to examine the binding capacity of bifidobacterial strains of human origin on mutagenic heterocyclic amines which are suspected to play a role in human cancers. In vitro binding of the mutagens Trp-p-2, IQ, MeIQx, 7,8DiMeIQx and PhIP by three bacterial strains in two media of different pH was analysed using high performance liquid chromatography. Bifidobacterium pseudocatenulatum G4 showed the highest decrease in the total HCAs content, followed by Bifidobacterium longum, and Escherichia coli. pH affects binding capacity; the highest binding was obtained at pH 6.8. Gram-positive tested strains were found to be consistently more effective than the gram-negative strain. There were significant decreases in the amount of HCAs in the presence of different cell concentrations of B. pseudocatenulatum G4; the highest decrease was detected at the concentration of 10(10) cfu/ml. The results showed that HCAs were able to bind with all bacterial strains tested in vitro, thus it may be possible to decrease their absorption by human intestine and increase their elimination via faeces.
    Matched MeSH terms: Heterocyclic Compounds/metabolism*
  6. Shamsudin S, Selamat J, Sanny M, Jambari NN, Sukor R, Praveena SM, et al.
    Molecules, 2020 Aug 26;25(17).
    PMID: 32858787 DOI: 10.3390/molecules25173874
    Heterocyclic amines (HCAs) are carcinogenic food toxicants formed in cooked meats, which may increase the risk of cancer development in humans. Therefore, in this study, the effect of stingless bee honey from different botanical origins on the formation of HCAs in grilled beef satay was investigated. HCAs concentration in grilled beef satay was determined by using high performance liquid chromatography (HPLC). In total, six of the most toxigenic HCAs representing aminoimidazo-azaarenes (AIAs) (MeIQx, 4,8-DiMeIQx, and PhIP) and amino carbolines (norharman, harman, and AαC) groups were identified in all the beef samples investigated. A significant reduction in HCAs was observed in grilled beef marinated in honey as compared to beef samples marinated in table sugar (control), in which the reduction of 95.14%, 88.45%, 85.65%, and 57.22% was observed in gelam, starfruit, acacia, and Apis honey marinades, respectively. According to the partial least squares regression (PLS) model, the inhibition of HCAs in grilled beef was shown to be significantly correlated to the antioxidant activity (IC50) of the honey samples. Therefore, the results of this study revealed that the addition of stingless bee honey could play an important role in reducing HCAs in grilled beef.
    Matched MeSH terms: Heterocyclic Compounds/analysis*
  7. Zulkefeli M, Hisamatsu Y, Suzuki A, Miyazawa Y, Shiro M, Aoki S
    Chem Asian J, 2014 Oct;9(10):2831-41.
    PMID: 25080369 DOI: 10.1002/asia.201402513
    In our previous paper, we reported that a dimeric Zn(2+) complex with a 2,2'-bipyridyl linker (Zn2L(1)), cyanuric acid (CA), and a Cu(2+) ion automatically assemble in aqueous solution to form 4:4:4 complex 3, which selectively catalyzes the hydrolysis of mono(4-nitrophenyl)phosphate (MNP) at neutral pH. Herein, we report that the use of barbital (Bar) instead of CA for the self-assembly with Zn2L(1) and Cu(2+) induces 2:2:2 complexation of these components, and not the 4:4:4 complex, to form supramolecular complex 6 a, the structure and equilibrium characteristics of which were studied by analytical and physical measurements. The finding show that 6 a also accelerates the hydrolysis of MNP, similarly to 3. Moreover, inspired by the crystal structure of 6 a, we prepared barbital units that contain functional groups on their side chains in an attempt to produce supramolecular phosphatases that possess functional groups near the Cu2(μ-OH)2 catalytic core so as to mimic the catalytic center of alkaline phosphatase (AP).
    Matched MeSH terms: Heterocyclic Compounds/chemistry*
  8. Phing SH, Mazhorova A, Shalaby M, Peccianti M, Clerici M, Pasquazi A, et al.
    Sci Rep, 2015;5:8551.
    PMID: 25711343 DOI: 10.1038/srep08551
    Terahertz technologies recently emerged as outstanding candidates for a variety of applications in such sectors as security, biomedical, pharmaceutical, aero spatial, etc. Imaging the terahertz field, however, still remains a challenge, particularly when sub-wavelength resolutions are involved. Here we demonstrate an all-optical technique for the terahertz near-field imaging directly at the source plane. A thin layer (<100 nm-thickness) of photo carriers is induced on the surface of the terahertz generation crystal, which acts as an all-optical, virtual blade for terahertz near-field imaging via a knife-edge technique. Remarkably, and in spite of the fact that the proposed approach does not require any mechanical probe, such as tips or apertures, we are able to demonstrate the imaging of a terahertz source with deeply sub-wavelength features (<30 μm) directly in its emission plane.
    Matched MeSH terms: Heterocyclic Compounds
  9. Barrio JD, Liu J, Brady RA, Tan CSY, Chiodini S, Ricci M, et al.
    J Am Chem Soc, 2019 09 11;141(36):14021-14025.
    PMID: 31422657 DOI: 10.1021/jacs.9b07506
    The binding of imidazolium salts to cucurbit[8]uril, CB[8], triggers a stepwise self-assembly process with semiflexible polymer chains and crystalline nanostructures as early- and late-stage species, respectively. In such a process, which involves the crystallization of the host-guest complexes, the guest plays a critical role in directing self-assembly toward desirable morphologies. These include platelet-like aggregates and two-dimensional (2D) fibers, which, moreover, exhibit viscoelastic and lyotropic properties. Our observations provide a deeper understanding of the self-assembly of CB[8] complexes, with fundamental implications in the design of functional 2D systems and crystalline materials.
    Matched MeSH terms: Heterocyclic Compounds
  10. Ramli SB, Ravoof TB, Tahir MI, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Jul 1;71(Pt 7):o475-6.
    PMID: 26279916 DOI: 10.1107/S205698901501107X
    In the title compound, C15H16N2S3 {systematic name: [({[(4-methyl-phen-yl)meth-yl]sulfan-yl}methane-thio-yl)amino][1-(thio-phen-2-yl)ethyl-idene]amine}, the central CN2S2 residue is almost planar (r.m.s. deviation = 0.0061 Å) and forms dihedral angles of 7.39 (10) and 64.91 (5)° with the thienyl and p-tolyl rings, respectively; the dihedral angle between these rings is 57.52 (6)°. The non-thione S atoms are syn, and with respect to the thione S atom, the benzyl group is anti. In the crystal, centrosymmetrically related mol-ecules self-associate via eight-membered {⋯HNCS}2 synthons. The dimeric aggregates stack along the a axis and are are consolidated into a three-dimensional architecture via methyl-C-H⋯π(benzene) and benzene-C-H⋯π(thien-yl) inter-actions.
    Matched MeSH terms: Heterocyclic Compounds
  11. Tagg T, McAdam CJ, Robinson BH, Simpson J
    Acta Crystallogr E Crystallogr Commun, 2015 Jul 1;71(Pt 7):816-20.
    PMID: 26279875 DOI: 10.1107/S2056989015011494
    The title compound, C16H10, crystallizes with four unique mol-ecules, designated 1-4, in the asymmetric unit of the monoclinic unit cell. None of the mol-ecules is planar, with the benzene rings of mol-ecules 1-4 inclined to one another at angles of 42.41 (4), 24.07 (6), 42.59 (4) and 46.88 (4)°, respectively. In the crystal, weak C-H⋯π(ring) interactions, augmented by even weaker C C-H⋯π(alkyne) contacts, generate a three-dimensional network structure with inter-linked columns of mol-ecules formed along the c-axis direction.
    Matched MeSH terms: Heterocyclic Compounds
  12. 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.
    Matched MeSH terms: Heterocyclic Compounds
  13. Tan YS, Yeo CI, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Aug 1;71(Pt 8):886-9.
    PMID: 26396747 DOI: 10.1107/S2056989015012682
    The title compound, [Fe(C17H14PS)2], is a second monoclinic polymorph (P21/c, with Z' = 1) of the previously reported monoclinic (C2/c, with Z' = 1/2) form [Fang et al. (1995 ▸). Polyhedron, 14, 2403-2409]. In the new form, the S atoms lie to the same side of the mol-ecule with the pseudo S-P⋯P-S torsion angle being -53.09 (3)°. By contrast to this almost syn disposition, in the C2/c polymorph, the Fe atom lies on a centre of inversion so that the S atoms are strictly anti, with a pseudo-S-P⋯P-S torsion angle of 180°. The significant difference in mol-ecular conformation between the two forms does not result in major perturbations in the P=S bond lengths nor in the distorted tetra-hedral geometries about the P atoms. The crystal packing of the new monoclinic polymorph features weak Cp-C-H⋯π(phen-yl) inter-actions consolidating linear supra-molecular chains along the a axis. These pack with no directional inter-actions between them.
    Matched MeSH terms: Heterocyclic Compounds
  14. 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.
    Matched MeSH terms: Heterocyclic Compounds
  15. Adam F, Smitha K, Charishma SP, Samshuddin S, Ameram N
    Acta Crystallogr E Crystallogr Commun, 2015 Dec 1;71(Pt 12):o1095-6.
    PMID: 26870516 DOI: 10.1107/S2056989015024792
    The title compound, C20H20N2O, was studied as a part of our work on pyrazoline derivatives. It represents a trans-isomer. The central pyrazoline ring adopts an envelope conformation with the asymmetric C atom having the largest deviation of 0.107 (1) Å from the mean plane. It forms dihedral angles of 6.2 (1) and 86.4 (1)° with the adjacent p-tolyl and styrene groups, respectively. In the crystal, C-H⋯O inter-actions link mol-ecules into infinite chains along the c axis.
    Matched MeSH terms: Heterocyclic Compounds
  16. Amin NABM, Hussen RSD, Lee SM, Halcovitch NR, Jotani MM, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2017 May 01;73(Pt 5):667-672.
    PMID: 28529772 DOI: 10.1107/S2056989017005072
    The Sn(IV) atom in the title diorganotin compound, [Sn(C7H6F)2Cl2(C2H6OS)2], is located on a centre of inversion, resulting in the C2Cl2O2 donor set having an all-trans disposition of like atoms. The coordination geometry approximates an octa-hedron. The crystal features C-H⋯F, C-H⋯Cl and C-H⋯π inter-actions, giving rise to a three-dimensional network. The respective influences of the Cl⋯H/H⋯Cl and F⋯H/H⋯F contacts to the mol-ecular packing are clearly evident from the analysis of the Hirshfeld surface.
    Matched MeSH terms: Heterocyclic Compounds
  17. Zukerman-Schpector J, Prado KE, Name LL, Cella R, Jotani MM, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2017 Jun 01;73(Pt 6):918-924.
    PMID: 28638659 DOI: 10.1107/S2056989017007605
    The title organoselenium compound, C19H13ClO3Se {systematic name: 2-[(4-chloro-phen-yl)selan-yl]-2H,3H,4H,5H,6H-naphtho-[1,2-b]pyran-5,6-dione}, has the substituted 2-pyranyl ring in a half-chair conformation with the methyl-ene-C atom bound to the methine-C atom being the flap atom. The dihedral angle between the two aromatic regions of the mol-ecule is 9.96 (9)° and indicates a step-like conformation. An intra-molecular Se⋯O inter-action of 2.8122 (13) Å is noted. In the crystal, π-π contacts between naphthyl rings [inter-centroid distance = 3.7213 (12) Å] and between naphthyl and chloro-benzene rings [inter-centroid distance = 3.7715 (13) Å], along with C-Cl⋯π(chloro-benzene) contacts, lead to supra-molecular layers parallel to the ab plane, which are connected into a three-dimensional architecture via methyl-ene-C-H⋯O(carbon-yl) inter-actions. The contributions of these and other weak contacts to the Hirshfeld surface is described.
    Matched MeSH terms: Heterocyclic Compounds
  18. Mohamad R, Awang N, Kamaludin NF, Jotani MM, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2017 Feb 01;73(Pt 2):260-265.
    PMID: 28217355 DOI: 10.1107/S2056989017001098
    The complete mol-ecule of the title compound, [Sn(C4H9)2(C5H10NOS2)2], is generated by a crystallographic mirror plane, with the SnIV atom and the two inner methyl-ene C atoms of the butyl ligands lying on the mirror plane; statistical disorder is noted in the two terminal ethyl groups, which deviate from mirror symmetry. The di-thio-carbamate ligand coordinates to the metal atom in an asymmetric mode with the resulting C2S4 donor set defining a skew trapezoidal bipyramidal geometry; the n-butyl groups are disposed to lie over the longer Sn-S bonds. Supra-molecular chains aligned along the a-axis direction and sustained by methyl-ene-C-H⋯S(weakly coordinating) inter-actions feature in the mol-ecular packing. A Hirshfeld surface analysis reveals the dominance of H⋯H contacts in the crystal.
    Matched MeSH terms: Heterocyclic Compounds
  19. Tan SL, Lee SM, Heard PJ, Halcovitch NR, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2017 Feb 01;73(Pt 2):213-218.
    PMID: 28217345 DOI: 10.1107/S2056989017000755
    The title compound, [Re(C3H6NS2)(C2H3N)(CO)3], features an octa-hedrally coordinated Re(I) atom within a C3NS2 donor set defined by three carbonyl ligands in a facial arrangement, an aceto-nitrile N atom and two S atoms derived from a symmetrically coordinating di-thio-carbamate ligand. In the crystal, di-thio-carbamate-methyl-H⋯O(carbon-yl) inter-actions lead to supra-molecular chains along [36-1]; both di-thio-carbamate S atoms participate in intra-molecular methyl-H⋯S inter-actions. Further but weaker aceto-nitrile-C-H⋯O(carbonyl) inter-actions assemble mol-ecules in the ab plane. The nature of the supra-molecular assembly was also probed by a Hirshfeld surface analysis. Despite their weak nature, the C-H⋯O contacts are predominant on the Hirshfeld surface and, indeed, on those of related [Re(CO)3(C3H6NS2)L] structures.
    Matched MeSH terms: Heterocyclic Compounds
  20. Kwong HC, Sim A, Chidan Kumar CS, Then LY, Win YF, Quah CK, et al.
    Acta Crystallogr E Crystallogr Commun, 2017 Dec 01;73(Pt 12):1812-1816.
    PMID: 29250392 DOI: 10.1107/S205698901701564X
    The asymmetric unit of the title compound, C24H14F4O2, comprises of one and a half mol-ecules; the half-mol-ecule is completed by crystallographic inversion symmetry. In the crystal, mol-ecules are linked into a three-dimensional network by C-H⋯F and C-H⋯O hydrogen bonds. Some of the C-H⋯F links are unusually short (< 2.20 Å). Hirshfeld surface analyses (dnorm surfaces and two-dimensional fingerprint plots) for the title compound are presented and discussed.
    Matched MeSH terms: Heterocyclic Compounds
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