ABSTRACT
A tetra-nuclear ZnII complex, [Zn4(C13H11N6O)2Cl6(H2O)2] or {[Zn2(HL)(H2O)(Cl2)](µCl)2[Zn2(HL)(H2O)(Cl)]}2, was synthesized by mixing an equimolar amount of a methanol solution containing ZnCl2 and a methanol solution containing the ligand H2 L [1,5-bis-(pyridin-2-yl-methyl-ene)carbono-hydrazide]. In the tetra-nuclear complex, each of the two ligand mol-ecules forms a dinuclear unit that is connected to another dinuclear unit by two bridging chloride anions. In each dinuclear unit, one ZnII cation is penta-coordinated in a N2OCl2 in a distorted square-pyramidal geometry, while the other ZnII cation is hexa-coordinated in a N3OCl2 environment with a distorted octa-hedral geometry. The basal plane around the penta-coordinated ZnII cation is formed by one chloride anion, one oxygen atom, one imino nitro-gen atom and one pyridine nitro-gen atom with the apical position occupied by a chloride anion. The basal plane of the hexa-coordinated ZnII cation is formed by one chloride anion, one hydrazinyl nitro-gen atom, one imino nitro-gen atom and one pyridine nitro-gen atom with the apical positions occupied by a water oxygen atom and a bridged chloro anion from another dinuclear unit, leading to a tetra-nuclear complex. A series of intra-molecular C-Hâ¯Cl hydrogen bonds is observed in each tetra-nuclear unit. In the crystal, the tetra-nuclear units are connected by inter-molecular C-Hâ¯Cl, C-Hâ¯O and N-Hâ¯O hydrogen bonds, forming a planar two-dimensional structure in the ac plane.
ABSTRACT
The binuclear complex, [Sn2(C4H9)4(C16H10N4O4)], contains two Sn4+ ions, connected by doubly N-deprotonated oxalylbis[(2-oxido-benzyl-idene)hydrazide] ligands, and each Sn4+ ion is linked to two tert-butyl groups. The coordination sphere of each Sn atom is best described as a distorted trigonal bipyramid. Each stannic ion in the complex is in a C2O2N environment. The two homologous parts of the doubly deprotonated ligand are located in trans positions with respect to the C-C bond of the oxalamide group. The oxalamide group exhibits an asymmetric coordination geometry, as seen by the slight difference between the C-O and C-N bond lengths. The three-dimensional network is a multilayer of complex mol-ecules with no strong supramolecular inter-actions.
ABSTRACT
INTRODUCTION: Sucking is innate in both infants and young children. It is termed nutritive when referring to suckling from the breast or bottle-feeding and non-nutritive when applied to sucking of a digit or pacifier. Few studies have attempted to assess the impact of the type of sucking on the size of the dental arches. The aim of this study was to quantify the influence of the mode of nutritive suckling and non-nutritive sucking habits (NNSH) on the measurements of the dental arches. PATIENTS AND METHODS: This was a transverse descriptive study involving 226 Senegalese children. The mode of feeding and the presence or not of a NNSH (digit or pacifier) were gathered from parents of all children using a structured questionnaire. Quantitative variables regarding intra- and inter-arch relationships were recorded using plaster moulds taken from the children. Statistical analyses were used to compare the different variables according to gender, the mode of feeding and the presence or not of a NNSH. RESULTS: The subjects in the study (123 boys and 103 girls) were aged between 5 and 6years old. The children who had enjoyed mixed feeding (breast/bottle combination) had a great length of the anterior maxillary arch and a significantly greater depth of the palatal arch than children receiving breast-feeding alone. The children with antecedents or a current NNSH had a longer anterior maxillary arch than subjects with no NNSH (P=0.01). Regarding inter-arch relationships, the children with antecedents or a current digit-sucking habit had less overbite than their peers who had no NNSH (P=0.04). CONCLUSION: The results of this study show that bottle-feeding, even partial, as well as NNSH are associated with changes in certain dimensions of the maxillary dental arch and in inter-arch relationships. Longitudinal studies are required to investigate further the nature of this association.