Displaying publications 61 - 80 of 162 in total

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  1. Fulltext 4,6-Dimeth-oxy-2-(methyl-sulfan-yl)pyrimidine-4-hy-droxy-benzoic acid (1/1)
    Thanigaimani K, Farhadikoutenaei A, Arshad S, Razak IA, Balasubramani K
    Acta Crystallogr Sect E Struct Rep Online, 2012 Dec 1;68(Pt 12):o3415-6.
    PMID: 23476237 DOI: 10.1107/S1600536812046338
    The base mol-ecule of the title co-crystal, C7H10N2O2S·C7H6O3, is essentially planar, with a maximum deviation of 0.0806 (14) Å for all non-H atoms. The acid mol-ecule is also nearly planar, with a dihedral angle of 8.12 (14)° between the benzene ring and the carb-oxy group. In the crystal, the acid mol-ecules form an inversion dimer through a pair of O-H⋯O hydrogen bonds with an R2(2)(8) ring motif. The pyrimidine mol-ecules are linked on both sides of the dimer into a heterotetra-mer via O-H⋯N and C-H⋯O hydrogen bonds with R2(2)(8) ring motifs. The heterotetra-mers are further linked by weak C-H⋯O hydrogen bonds, forming a tape structure along [1-10].
  2. Fulltext 2-Amino-5-methyl-pyridinium 2-hy-droxy-5-chloro-benzoate
    Thanigaimani K, Farhadikoutenaei A, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2013 Jan 1;69(Pt 1):o132-3.
    PMID: 23476391 DOI: 10.1107/S160053681205101X
    In the 5-chloro-salicylate anion of the title salt, C6H9N2(+)·C7H4ClO3(-), an intra-molecular O-H⋯O hydrogen bond with an S(6) graph-set motif is observed and the dihedral angle between the benzene ring and the -CO2 group is 1.6 (6)°. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl-ate O atoms via a pair of N-H⋯O hydrogen bonds, forming an R2(2)(8) ring motif. The crystal structure also features N-H⋯O and weak C-H⋯O inter-actions, resulting in a layer parallel to (10-1).
  3. Fulltext 2,3-Diamino-pyridinium 4-meth-oxy-quinoline-2-carboxyl-ate
    Thanigaimani K, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Dec 1;68(Pt 12):o3444-5.
    PMID: 23476259 DOI: 10.1107/S1600536812047642
    In the 4-meth-oxy-quinoline-2-carboxyl-ate anion of the title salt, C5H8N3(+)·C11H8NO3(-), the dihedral angle between the quinoline ring system and the carboxyl-ate group is 16.54 (15)°. In the crystal, the cations and anions are linked via N-H⋯O and N-H⋯N hydrogen bonds, forming a centrosymmetric 2 + 2 aggregate with R2(2)(9) and R4(2)(8) ring motifs. These units are further connected via N-H⋯O hydrogen bonds into a layer parallel to the bc plane. The crystal structure is also stabilized by weak C-H⋯O hydrogen bonds and π-π inter-actions between pyridine rings [centroid-centroid distance = 3.5886 (8) Å] and between pyridine and benzene rings [centroid-centroid distance = 3.6328 (8) Å].
  4. Fulltext 2-Amino-5-methyl-pyridinium 6-oxo-1,6-dihydro-pyridine-2-carboxyl-ate
    Thanigaimani K, Farhadikoutenaei A, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Nov 1;68(Pt 11):o3151-2.
    PMID: 23284469 DOI: 10.1107/S1600536812041359
    The anion of the title salt, C(6)H(9)N(2) (+)·C(6)H(4)NO(3) (-), undergoes an enol-to-keto tautomerism during the crystallization. In the crystal structure, the cation and anion are held together by a relatively short N-H⋯O hydrogen bond, and the two anions are further connected to each other by a pair of N-H⋯O hydrogen bonds with an R(2) (2)(8) ring motif, thus forming a centrosymmetric 2 + 2 aggregate. The aggregates are further linked through weak N-H⋯O and C-H⋯O hydrogen bonds, resulting a three-dimensional network.
  5. Fulltext 5-Amino-6-methyl-quinolin-1-ium hydrogen malonate-malonic acid (2/1)
    Thanigaimani K, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2013 Mar 1;69(Pt 3):o319-20.
    PMID: 23476518 DOI: 10.1107/S1600536813002547
    The asymmetric unit of the title compound, 2C10H11N2(+)·2C3H3O4(-)·C3H4O4, consists of one 5-amino-6-methyl-quinolin-1-ium cation, one hydrogen malonate (2-carb-oxy-acetate) anion and one-half mol-ecule of malonic acid which lies on a twofold rotation axis. The quinoline ring system is essentially planar, with a maximum deviation of 0.062 (2) Å for all non-H atoms. In the anion, an intra-molecular O-H⋯O hydrogen bond generates an S(6) ring. In the crystal, the components are linked via N-H⋯O and O-H⋯O hydrogen bonds into layers parallel to the ac plane. The crystal structure also features weak C-H⋯O hydrogen bonds and a π-π stacking inter-action with a centroid-centroid distance of 3.8189 (10) Å.
  6. Fulltext 8-Hy-droxy-5,7-dimethyl-quinolin-1-ium hydrogen sulfate
    Thanigaimani K, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2013 Jan 1;69(Pt 1):o42-3.
    PMID: 23476427 DOI: 10.1107/S1600536812049483
    The quinoline ring system of the title salt, C11H12NO(+)·HSO4(-), is essentially planar, with a maximum deviation of 0.054 (2) Å for all non H atoms. In the crystal, the cations and anions are linked via N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds, and are stacked respectively in columns along the a axis. π-π stacking inter-actions, with centroid-centroid distances of 3.5473 (12) and 3.6926 (12) Å, are also observed. The crystal studied was an inversion twin with refined components of 0.43 (7):0.57 (7).
  7. Fulltext 2-Amino-5-methyl-pyridinium 4-chloro-benzoate
    Thanigaimani K, Farhadikoutenaei A, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2013 Jan 1;69(Pt 1):o134-5.
    PMID: 23476392 DOI: 10.1107/S1600536812051021
    The 4-chloro-benzoate anion of the title salt, C6H9N2(+)·C7H4ClO2(-), is nearly planar with a dihedral angle of 5.14 (16)° between the benzene ring and the carboxyl-ate group. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl-ate O atoms of the anion via a pair of N-H⋯O hydrogen bonds with an R2(2)(8) ring motif. The ion pairs are further connected via N-H⋯O and weak C-H⋯O hydrogen bonds, forming a two-dimensional network parallel to the bc plane. The crystal structure also features a π-π stacking inter-action between the pyridinium and benzene rings with a centroid-centroid distance of 3.7948 (9) Å.
  8. Fulltext 2-Amino-6-methyl-pyridinium 3-chloro-benzoate
    Thanigaimani K, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2013 Mar 1;69(Pt 3):o318.
    PMID: 23476517 DOI: 10.1107/S1600536813002559
    In the title salt, C6H9N2(+)·C7H4ClO2(-), the 3-chloro-benzoate anion shows a whole-mol-ecule disorder over two positions with a refined occupancy ratio of 0.505 (4):0.495 (4). In the crystal, the cations and anions are linked via N-H⋯O hydrogen bonds, forming a centrosymmetric 2 + 2 aggregate with R2(2)(8) and R4(2)(8) ring motifs. The crystal structure also features a π-π stacking inter-action between the pyridinium rings with a centroid-centroid distance of 3.8339 (9) Å.
  9. Fulltext 2-Amino-5-methyl-pyridinium 4-methyl-benzoate
    Thanigaimani K, Farhadikoutenaei A, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2013 Jan 1;69(Pt 1):o94-5.
    PMID: 23476474 DOI: 10.1107/S1600536812050374
    The 4-methyl-benzoate anion of the title salt, C6H9N2(+)·C8H7O2(-), is nearly planar, with a dihedral angle of 6.26 (10)° between the benzene ring and the carboxyl-ate group. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl-ate O atoms of the anion via a pair of N-H⋯O hydrogen bonds with an R2(2)(8) ring motif, forming an approximately planar ion pair with a dihedral angle of 9.63 (4)° between the pyridinium and benzene rings. The ion pairs are further connected via N-H⋯O and weak C-H⋯O hydrogen bonds, forming a two-dimensional network parallel to the bc plane.
  10. Fulltext 2,3-Diamino-pyridinium hydrogen malonate
    Thanigaimani K, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2013 Jan 1;69(Pt 1):o92-3.
    PMID: 23476473 DOI: 10.1107/S1600536812050386
    In the title mol-ecular salt, C5H8N3(+)·C3H3O4(-), the cation is essentially planar, with a maximum deviation of 0.005 (1) Å for all non-H atoms. In the anion, an intra-molecular O-H⋯O hydrogen bond generates an S(6) ring. In the crystal, the cations and anions are connected via N-H⋯O hydrogen bonds and a weak C-H⋯O inter-action, forming layers parallel to the ab plane.
  11. Fulltext 8-Hy-droxy-5,7-dimethyl-quinolin-1-ium chloride dihydrate
    Thanigaimani K, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2013 Jan 1;69(Pt 1):o44.
    PMID: 23476428 DOI: 10.1107/S1600536812049495
    In the title hydrated salt, C11H12NO(+)·Cl(-)·2H2O, the quinoline ring system is essentially planar, with a maximum deviation of 0.005 (1) Å for all non-H atoms. In the crystal, the three components are linked by O-H⋯O, N-H⋯O, O-H⋯Cl and weak C-H⋯O hydrogen bonds, forming a layer structure parallel to the ac plane. The crystal structure is further stabilized by π-π stacking inter-actions, with centroid-centroid distances of 3.5213 (6) and 3.7176 (6) Å.
  12. Fulltext 2-Amino-5-methyl-pyridinium 2-amino-benzoate
    Thanigaimani K, Farhadikoutenaei A, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Nov 1;68(Pt 11):o3196-7.
    PMID: 23284507 DOI: 10.1107/S1600536812043243
    In the 2-amino-benzoate anion of the title salt, C(6)H(9)N(2) (+)·C(7)H(6)NO(2) (-), an intra-molecular N-H⋯O hydrogen bond is observed. The dihedral angle between the ring and the CO(2) group is 8.41 (13)°. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl-ate O atoms via a pair of N-H⋯O hydrogen bonds, forming an R(2) (2)(8) ring motif. The ion pairs are further connected via N-H⋯O hydrogen bonds, resulting in a donor-donor-acceptor-acceptor (DDAA) array of quadruple hydrogen bonds. The crystal structure also features a weak N-H⋯O hydrogen bond and a C-H⋯π inter-action, resulting in a three-dimensional network.
  13. Fulltext 2-Amino-5-methyl-pyridinium 3-chloro-benzoate
    Thanigaimani K, Farhadikoutenaei A, Khalib NC, Arshad S, Razak IA
    Acta Crystallogr Sect E Struct Rep Online, 2012 Nov 1;68(Pt 11):o3195.
    PMID: 23284506 DOI: 10.1107/S1600536812043231
    The 3-chloro-benzoate anion of the title salt, C(6)H(9)N(2) (+)·C(7)H(4)ClO(2) (-), is nearly planar with a dihedral angle of 2.44 (13)° between the benzene ring and the carboxyl-ate group. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxyl-ate O atoms of the anion via a pair of N-H⋯O hydrogen bonds with an R(2) (2)(8) ring motif, forming an approximately planar ion pair with a dihedral angle of 7.92 (5)° between the pyridinium and benzene rings. The ion pairs are further connected via N-H⋯O and C-H⋯O hydrogen bonds, forming a two-dimensional network parallel to the bc plane.
  14. Bis(dicyclohexylammonium 3-thienylacetate)
    Ng SW, Chantrapromma S, Razak IA, Fun HK
    Acta Crystallogr C, 2001 Mar;57(Pt 3):291-2.
    PMID: 11250582
    The triclinic cell of the title compound contains 2C(12)H(24)N(+) x 2C(6)H(5)O(2)S(-) ion pairs that are linked by four hydrogen bonds [N...O = 2.728 (3) and 2.758 (3) A] across a centre of inversion.
  15. 1-acetyl-3-[benzoyl(4-methoxyphenyl)methylene]-2,3-dihydro-1H-indol-2-one
    Usman A, Razak IA, Fun HK, Chantrapromma S, Zhang Y, Xu JH
    Acta Crystallogr C, 2001 Dec;57(Pt 12):1438-40.
    PMID: 11740110
    In the title compound, C25H19NO4, the indole moiety is not completely planar, the heterocyclic ring being distorted very slightly towards a half-chair conformation. The benzoyl and 4-methoxyphenyl substituents are individually almost planar and are in a bisecting and nearly perpendicular configuration, respectively, with respect to the plane of the indole moiety. The molecular and packing structures in the crystal are stabilized by intramolecular and intermolecular C-H...O interactions.
  16. (Piperidine-1-carbodithioato-S,S')bis(triphenylphosphine-P)gold(I)
    Razak IA, Raj SS, Fun HK, Jian F, Bei F, Yang X, et al.
    Acta Crystallogr C, 2000 Jun;56 (Pt 6):666-7.
    PMID: 10902013
  17. Utilization, knowledge and attitudes concerning sealants among Malaysian dentists: a national survey
    Abdul Razak IA, Esa R, Jalallundin RL, Jaafar N
    J Pedod, 1990;14(4):242-5.
    PMID: 2098079
    The aim of this postal survey was to assess the utilization, knowledge and attitude concerning sealants among Malaysian dentists. A pretested questionnaire was sent to all dentists (1217) who were on the Dentist Register of Malaysia of 1987. A response rate of 61.1% was obtained. The results indicate that 52.6% of the respondents have used sealants, but of these only 13.6% have used them frequently. The two "knowledge" related questions receiving the most support concerned the suitability of the first permanent molars for sealants and the loss of sealants attributable to problems at the time of application. The two "attitudinal" questions receiving the most support concerned the value of sealants in preventing dental caries and the need for the profession to expand more efforts toward increasing public demand for sealants. Only about 50% of the respondents believed that sealants are cost-effective.
  18. An analysis of sugar content of commonly used pediatric liquid medicines--its relevance to dentistry
    Nik-Hussein NN, Razak IA, Karim MN
    Singapore Dent J, 1988 Dec;13(1):24-6.
    PMID: 3154999
    The sugar content of twenty-four liquid medicines commonly prescribed for infants and young children were measured and the type of sugars present were also identified in four randomly selected samples. All the liquid medicines tested contained sugar, in the range of 29.4% to 61.2%. Sucrose appeared to be the most commonly used sugar. Whilst it is agreed that sucrose makes the medicine more acceptable to children, its continual use by the pharmaceutical industry should be discontinued due to its harmful effect on the dental health of children, particularly those taking these syrup-based medicines on prolonged basis. Sugar-free alternatives such as sorbitol or saccharin should be used instead.
  19. Knowledge, perceptions and clinical application of the shortened dental arch concept among Malaysian government dentists
    Kasim SKM, Razak IA, Yusof ZYM
    Int Dent J, 2018 Feb;68(1):31-38.
    PMID: 28782099 DOI: 10.1111/idj.12325
    AIM: To assess the knowledge and perceptions of Malaysian government dentists regarding the shortened dental arch (SDA) concept and its application in clinical practice.

    BACKGROUND: The SDA concept refers to a specific type of dentition with intact anterior teeth and a reduction in posterior occlusal pairs. Dentists' knowledge and perceptions of the SDA concept can influence its application in clinical practice.

    METHODS: A self-administered questionnaire on the SDA concept was distributed to 326 government dentists in the states of Selangor and Kuala Lumpur, Malaysia. The data were analysed using SPSS version 22 software.

    RESULTS: The response rate was 84.0%. The majority of respondents had good knowledge on five of six knowledge items and good attitudes towards 10 of 17 perception items. However, only one-fifth (20.4%) reported having applied the SDA concept in the clinic. A larger number of participants who graduated locally than who graduated abroad perceived that patients <60 years of age, without molar support, can attain acceptable chewing function and that SDA treatment does not lead to loss of occlusal vertical dimension (P < 0.05). A larger number of participants with ≤5 years of work experience than with >5 years of work experience perceived that the SDA concept enables simpler treatment planning (P < 0.05). Finally, a larger number of participants who graduated abroad than who graduated locally observed that patients without molar support had temporomandibular joint problems (P < 0.05).

    CONCLUSION: Although Malaysian government dentists have good knowledge and perceptions of the SDA concept, it is not widely applied in the clinic. Concerted efforts in SDA training of dentists are needed to help to shorten denture waiting lists and reduce costs.

  20. Fulltext Crystal structure and optical spectroscopic analyses of (E)-3-(1H-indol-2-yl)-1-(4-nitro-phen-yl)prop-2-en-1-one hemihydrate
    Zaini MF, Razak IA, Khairul WM, Arshad S
    Acta Crystallogr E Crystallogr Commun, 2018 Nov 01;74(Pt 11):1589-1594.
    PMID: 30443387 DOI: 10.1107/S2056989018014329
    The asymmetric unit of the title compound, 2C17H12N2O3·H2O comprises two mol-ecules of (E)-3-(1H-indol-2-yl)-1-(4-nitro-phen-yl)prop-2-en-1-one and a water mol-ecule. The main mol-ecule adopts an s-cis configuration with respect to the C=O and C=C bonds. The dihedral angle between the indole ring system and the nitro-substituted benzene ring is 37.64 (16)°. In the crystal, mol-ecules are linked by O--H⋯O and N-H⋯O hydrogen bonds, forming chains along [010]. In addition, weak C-H⋯O, C-H⋯π and π-π inter-actions further link the structure into a three-dimensional network. The optimized structure was generated theoretically via a density functional theory (DFT) approach at the B3LYP/6-311 G++(d,p) basis level and the HOMO-LUMO behaviour was elucidated to determine the energy gap. The obtained values of 2.70 eV (experimental) and 2.80 eV (DFT) are desirable for optoelectronic applications. The inter-molecular inter-actions were qu-anti-fied and analysed using Hirshfeld surface analysis.
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