The mol-ecular and crystal structure of two new chalcone derivatives, (E)-1-(anthracen-9-yl)-3-[4-(piperidin-1-yl)phen-yl]prop-2-en-1-one, C28H25NO, (I), and (E)-1-(anthracen-9-yl)-3-[4-(di-phenyl-amino)-phen-yl]prop-2-en-1-one, C35H25NO, (II), with the fused-ring system at the same position are described. In the crystals of (I) and (II), the mol-ecules are linked via C-H⋯O hydrogen bonds into inversion dimers, forming R22(22) and R22(14) ring motifs, respectively. Weak inter-molecular C-H⋯π inter-actions further help to stabilize the crystal structure, forming a two-dimensional architecture. The mol-ecular structures are optimized using density functional theory (DFT) at B3LYP/6-311 G++(d,p) level and compared with the experimental results. The smallest HOMO-LUMO energy gaps of (I) (exp . 2.76 eV and DFT 3.40 eV) and (II) (exp . 2.70 eV and DFT 3.28 eV) indicates the suitability of these crystals in optoelectronic applications. All inter-molecular contacts and weaker contributions involved in the supra-molecular stabilization are investigated using Hirshfeld surface analysis. The mol-ecular electrostatic potential (MEP) further identifies the positive, negative and neutral electrostatic potential regions of the mol-ecules.
The title chalcone compounds, C27H18O (I) and C33H20O (II), were synthesized using a Claisen-Schmidt condensation. Both compounds display an s-trans configuration of the enone moiety. The crystal structures feature inter-molecular C-H⋯O and C-H⋯π inter-actions. Quantum chemical analysis of density functional theory (DFT) with a B3LYP/6-311++G(d,p) basis set has been employed to study the structural properties of the compound. The effect of the inter-molecular inter-actions in the solid state are responsible for the differences between the experimental and theoretical optimized geometrical parameters. The small HOMO-LUMO energy gap in (I) (exp : 3.18 eV and DFT: 3.15 eV) and (II) (exp : 2.76 eV and DFT: 2.95 eV) indicates the suitability of these compounds for optoelectronic applications. The inter-molecular contacts and weak contributions to the supra-molecular stabilization are analysed using Hirshfeld surface analysis.
The title compound, C31H20O, was synthesized using a Claisen-Schmidt condensation. The enone group adopts an s-trans conformation and the anthracene ring systems are twisted at angles of 85.21 (19) and 83.98 (19)° from the enone plane. In the crystal, mol-ecules are connected into chains along [100] via weak C-H⋯π inter-actions. The observed band gap of 3.03 eV is in excellent agreement with that (3.07 eV) calculated using density functional theory (DFT) at the B3LYP/6-311++G(d,p) level. The Hirshfeld surface analysis indicates a high percentage of C⋯H/H⋯C (41.2%) contacts in the crystal.
The crystal structures of (E)-1-(anthracen-9-yl)-3-(3H-indol-2-yl)prop-2-en-1-one, C25H17NO, and (E)-1-(anthracen-9-yl)-3-[4-(di-methyl-amino)-naphthalen-1-yl]prop-2-en-1-one, C29H23NO, are reported. In each case the anthracene ring system and pendant ring system are almost perpendicular to each other [dihedral angles = 75.57 (7)° and 70.26 (10)°, respectively]. In the extended structures, weak N-H⋯O, C-H⋯O and C-H⋯π inter-actions influence the centrosymmetric crystal packing. Density functional theory calculations were carried out using a 6-311 G++(d,p) basis set and the calculated structures are in good agreement with the crystal structures. The compounds were also characterized by UV-Vis absorption spectroscopy and the smallest (HOMO-LUMO) energy gaps of 2.89 and 2.54 eV indicate the enhanced non-linear responses (inter-molecular charge transfers) of these systems.
The structures of two new anthracenyl chalcones, namely (E)-1-(anthracen-9-yl)-3-(4-nitro-phen-yl)prop-2-en-1-one, C23H15NO3, and (E)-1-(anthracen-9-yl)-3-(4-iodo-phen-yl)prop-2-en-1-one, C23H15IO are reported. A structural comparative study between the two chalcones was performed and some effects on the geometrical parameters, such as planarity and dihedral angles, are described. The mol-ecular geometry was determined by single-crystal X-ray diffraction, and density functional theory (DFT) at B3LYP with the 6-311++G(d,p) basis set was applied to optimize the ground-state geometry. In addition, inter-molecular inter-actions responsible for the crystal packing were analysed. The electronic properties, such as excitation energies and HOMO-LUMO energies were calculated by time-dependent density functional theory (TD-DFT) and the results complement the experimental findings. The mol-ecular electrostatic potential (MEP) was also investigated at the same level of theory in order to identify and qu-antify the possible reactive sites.
The asymmetric unit of the title hydrated salt, C13H11N2 (+)·C7H6NO2 (-)·2H2O, consists of two independent 9-amino-acridinium cations, two 4-amino-benzoate anions and four water mol-ecules. Both 9-amino-acridinium cations are essentially planar, with maximum deviations of 0.034 (1) and 0.025 (2) Å, and are protonated at the pyridine N atoms. The 4-amino-benzoate anions are approximately planar, with dihedral angles of 9.16 (19) and 5.4 (2)° between the benzene ring and the carboxyl-ate group. In the crystal, the two independent anions are connected by N-H⋯O hydrogen bonds, forming a layer parallel to (100). The layers are connected through the cations by N-H⋯N and N-H⋯O hydrogen bonds. The water mol-ecules, which form O-H⋯O hydrogen-bonded chains along the b-axis direction, connect the anions and the cations by O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds. The crystal structure also features π-π inter-actions [centroid-centroid distances = 3.6343 (9)-3.8366 (10) Å] and a C-H⋯π inter-action.
In the title salt, C6H9N2 (+)·C7H5O3 (-), the anion is essentially planar, with a dihedral angle of 2.72 (17)° between the benzene ring and the carboxyl-ate group. In the crystal, the anions are connected by O-H⋯O hydrogen bonds, forming a 41 helical chain along the c axis. 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. The ion pairs are further connected via another N-H⋯O hydrogen bond, resulting in a three-dimensional network.
In the 3-hy-droxy-picolinate anion of the title salt, C6H9N2 (+)·C6H4NO3 (-), an intra-molecular O-H⋯O hydrogen bond with an S(6) graph-set motif is formed, so that the anion is essentially planar, with a dihedral angle of 9.55 (9)° between the pyridine ring and the carboxyl-ate group. In the crystal, the cations and anions are linked via N-H⋯O hydrogen bonds, forming a centrosymmetric 2 + 2 aggregate with R 2 (2)(8) and R 4 (2)(8) ring motifs. The crystal structure also features N-H⋯N and weak C-H⋯π inter-actions.
The 4-methyl-benzoic acid mol-ecule of the title adduct, C10H11N5·C8H8O2, is approximately planar with a dihedral angle of 6.3 (2)° between the carb-oxy-lic acid group and the benzene ring. In the triazine mol-ecule, the plane of the triazine ring makes a dihedral angle of 29.2 (2)° with that of the adjacent benzene ring. In the crystal, the acid and base mol-ecules are linked via N-H⋯O and O-H⋯N hydrogen bonds with an R 2 (2)(8) motif, and the acid-base pairs are further connected via N-H⋯N hydrogen bonds with R 2 (2)(8) motifs, forming a supra-molecular ribbon along [101]. Between the tapes, a weak C-H⋯π inter-action is observed.
In the title compound, C19H18N2O3, the pyrazoline ring is close to being planar (r.m.s. deviation = 0.035 Å) and subtends dihedral angles of 2.11 (8) and 82.63 (8)° with the p-tolyl and benzene rings, respectively. In the crystal, C-H⋯O and C-H⋯N hydrogen bonds link the mol-ecules, forming a three-dimensional network. A weak C-H⋯π inter-action involving the benzene ring is also observed.
The asymmetric unit of the title salt, C10H11N2 (+)·C4H5O4 (-), consists of two independent 5-amino-6-methyl-quinolin-1-ium cations and two 3-carb-oxy-propano-ate anions. Both cations are protonated at the pyridine N atoms and are essentially planar, with maximum deviations of 0.026 (3) and 0.016 (2) Å. In the crystal, the cations and anions are linked via N-H⋯O and O-H⋯O hydrogen bonds, forming a layer parallel to the ab plane. In the layer, weak C-H⋯O hydrogen bonds and π-π stacking inter-actions, with centroid-to-centroid distances of 3.7283 (15) and 3.8467 (15) Å, are observed. The crystal structure also features weak C-H⋯O hydrogen bonds between the layers.
In the 5-chloro-salicylate anion of the title salt, C5H6BrN2 (+)·C7H4ClO3 (-), an intra-molecular O-H⋯O hydrogen bond with an S(6) graph-set motif is formed, so that the anion is essentially planar with a dihedral angle of 1.3 (5)° 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 via a pair of N-H⋯O hydrogen bonds, forming an R 2 (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 the (10-1) plane.
In the title compound, C(10)H(11)N(5)O, the triazine ring forms a dihedral angle of 10.37 (4)° with the benzene ring. In the crystal, adjacent mol-ecules are linked by a pair of N-H⋯N hydrogen bonds, forming an inversion dimer with an R(2) (2)(8) ring motif. The dimers are further connected via N-H⋯O and N-H⋯N hydrogen bonds, resulting in a three-dimensional network.
The asymmetric unit of the title compound, 2C(10)H(11)N(5)O·C(6)H(10)O(4), consists of a 2,4-diamino-6-(4-meth-oxy-phen-yl)-1,3,5-triazine mol-ecule and one-half mol-ecule of adipic acid which lies about an inversion center. The triazine ring makes a dihedral angle of 12.89 (4)° with the adjacent benzene ring. In the crystal, the components are linked by N-H⋯O and O-H⋯N hydrogen bonds, thus generating a centrosymmetric 2 + 1 unit of triazine and adipic acid mol-ecules with R(2) (2)(8) motifs. The triazine mol-ecules are connected to each other by N-H⋯N hydrogen bonds, forming an R(2) (2)(8) motif and a supra-molecular ribbon along the c axis. The 2 + 1 units and the supra-molecular ribbons are further inter-linked by weak N-H⋯O, C-H⋯O and C-H⋯π inter-actions, resulting in a three-dimensional network.
To determine the prevalence, distribution, severity and treatment need of enamel opacities among 11-12 year-old school children in a fluoridated urban community.
The Oral Health Division, Ministry of Health in Malaysia piloted clinical pathways (cpath) in primary care in early 2003. This study investigated the knowledge, perception of cpaths and barriers faced by the clinicians involved in the pilot project. Self-administered questionnaires were sent to the clinicians (n=191). Dentists (67.9%) and dental nurses (70.6%) had good overall knowledge of cpaths. The majority of the clinicians (67.9% to 95.6%) perceived cpath positively in all areas. Only 9.2% of dentists encountered difficulties in using cpath forms compared to 28.4% of dental nurses. A higher proportion of dental nurses (73.5%) compared to dentists (64.8%) were willing to continue using cpath. The majority of dentists (76.7%) and dental nurses (73.1%) were willing to participate in future development of cpaths. Overall, there was evidence of managerial support for the pilot project. A follow-up of the pilot project was somewhat lacking as less than half (43.3%) of the clinicians reported that the state coordinator obtained feedback from them. The findings auger well for the future implementation of cpath should the Oral Health Division decide to adopt cpath routinely in the public oral health care service.
The asymmetric unit of the title compound, 2C5H6ClN3O·C4H6O4, consists of one 4-chloro-6-meth-oxy-pyrimidin-2-amine mol-ecule and one half-mol-ecule of succinic acid which lies about an inversion centre. In the crystal, the acid and base mol-ecules are linked through N-H⋯O and O-H⋯N hydrogen bonds, forming a tape along [1-10] in which R2(2)(8) and R4(2)(8) hydrogen-bond motifs are observed. The tapes are further inter-linked through a pair of C-H⋯O hydrogen bonds into a sheet parallel to (11-2).
In the title salt, 2C4H6ClN4(+)·C4H2O4(2-), the complete fumarate dianion is generated by crystallographic inversion symmetry. The cation is essentially planar, with a maximum deviation of 0.018 (1) Å. In the anion, the carboxyl-ate group is twisted slightly away from the attached plane, the dihedral angle between the carboxyl-ate and (E)-but-2-ene planes being 12.78 (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 of the anion via a pair of N-H⋯O hydrogen bonds, forming an R2(2)(8) ring motif. In addition, another type of R2(2)(8) motif is formed by centrosymmetrically related pyrimidinium cations via N-H⋯N hydrogen bonds. These two combined motifs form a heterotetra-mer. The crystal structure is further stabilized by stong N-H⋯O, N-H⋯Cl and weak C-H⋯O hydrogen bonds, resulting a three-dimensional network.
In the title salt, C6H9N2(+)·C2F3O2(-), the F atoms of the anion are disordered over two sets of sites, with refined occupancies in a ratio of 0.505 (17):0.495 (17). In the crystal, cations and anions are linked via N-H⋯O hydrogen bonds, forming R2(2)(8) ring motifs. The ionic units are linked into a two-dimensional network parallel to (100) by N-H⋯O and weak C-H⋯O hydrogen bonds. The crystal structure is further stabilized by weak C-H⋯F hydrogen bonds, resulting in a three-dimensional network.
The title compound, C5H6ClN3O, is essentially planar with a maximum deviation of 0.0256 (11) Å for all non-H atoms. In the crystal, adjacent mol-ecules are linked by a pair of N-H⋯N hydrogen bonds, forming an inversion dimer with an R2(2)(8) ring motif. The dimers are further linked via N-H⋯O hydrogen bonds into an undulating sheet structure parallel to the bc plane.