• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.609-614
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• 2013

Extended H$\ddot{u}$ckel tight-binding band structure calculations are used to address the chemical bonding and elastic properties of $Zr_2AC$ (A=Al, Si, P, and S). Elastic properties are interpreted by analyzing the density of states and the crystal orbital overlap population for the respective phases. Our results show that the bulk modulus of these ternary compounds is determined by the strength of Zr-A bonds.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1079-1084
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• 1995

New cyclophanes having multilactam linkages were synthesized and characterized. One-pot coupling reaction of 2,6-pyridinedicarbonyl dichloride and a diamine gave a tetralactam, a hexalactam, and a octalactam in good yields. The TLC behaviour, the molecular symmetry shown by 1H NMR spectrum, and the fragmentation patterns shown by FAB mass spectrum of the octalactam support its monocyclic structure.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.2
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• pp.153-157
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• 2006

In this work, the effects of plasma treatment on surface properties of semiconductive silicone rubber were investigated in terms of X-ray photoelectron spectroscopy (XPS) and contact angles, The adhesion characteristics of semiconductive-insulating interface layer of silicone rubber were studied by measuring the T-peel strengths, The results of the chemical analysis showed that C-H bonds were broken due to plasma discharge and Silica-like bonds(SiOx, x=3${\~}$4) increased, It is thought that semiconductive silicone rubber surfaces treated with plasma discharge led to an increase in oxygen-containing functional groups, resulting in improving the degree of adhesion of the semiconductive-insulating interface layer of silicone rubber. However, the oxygen plama for 20 minute produces a damaged oxidized semiconductive silicone rubber layer, which acts as a weak layer producing a decrease in T-peel strength, These results are probably due to the modifications of surface functional groups or polar component of surface free energy of the semiconductive silicone rubber.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.13-16
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• 2008

This paper is to present the performance data for improved direct setting method using tile bond for application of porcelain tile under 1 percent absorptance. For this purpose, improved direct setting method type 1 & 2(tile bond curing time 0, 24H) were compared with the conventional setting methods(including direct setting method and improved pressure setting method) in the sight of the adhesive stability of porcelain tile. It tested for tiles after 14, 28days under standard condition and severe conditions. The severe conditions were water immersion, heat ageing(70℃) and freeze-thaw cycle. On the basis of test results, the adhesive strength of direct setting method was lowest for the conventional setting methods. But improved direct setting method using tile bonds(A, B) came close to the result of improved pressure setting method using tile bonds.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1527-1530
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• 2002

1,12-diazacyclodocosane-2,11-dione was first isolated from a plant Phyllanthus niruri Linn. Its structure has been determined by means of spectroscopy methods and X-ray crystallography. Two peptide groups in the big ring (lactam) are the main factors influencing intermolecular contacts. The hydrogen-bond interaction of these hydrophilic groups is observed in the crystal structure. Meanwhile, C-H···O hydrogen bonds in molecules contribute to the formation of the whole crystal. These two kinds of hydrogen-bond form six- member rings among molecules. This compound crystallizes in the triclinic space group P-1 with a= 9.588(1) $\AA$, b= $9.850(1)\AA$, c = $11.810(1)\AA$, $\alpha=$ 68.18(1)$^{\circ}C$ , $\beta=$ 84.98(1), $\gamma$ = 86.03(1)$^{\circ}C$ , V = $1030.66(17)\AA3$ , Z = 2. A disorder of five-member carbon chain in the whole ring is observed in the title compound. The bond angle 105.8(4) is determined for a extreme configuration C(14)-C(15)-C(16), and 117.7(10) for another extreme configuration C(14')-C(15')-C(16'). In this crystal, two molecules are tied each other by short intermolecular hydrogen bonds, the oxygen atom being tied by hydrogen bond to nitrogen atom of another two molecules. The NMR and IR spectral data coincides to the structure of the compound.

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.265-270
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• 1991

Theoretical calculations on the stabilization energies of framework atoms in hydrolyses Co(Ⅱ )-exchanged zeolite A were made using some potential energy functions and optimization program. The protons which are produced by hydrolysis of $[Co(H_2O)_n]^{2+}$ ion in large cavity showed a tendency to attack the framework oxygen atom O(1) preferentially, and the oxygen atom O(4) within OH- ion was coordinated at Al atom. The weakness of bonds between T(Si, Al) and oxygen by attack of proton and too large coordination number around small aluminum atom will make the framework of Co(Ⅱ)-exchanged zeolite A more unstable. The stabilization energy of $Co_4Na_4$-A framework (- 361.57 kcal/mol) was less than that of thermally stable zeolite A($Na_{12-}$A: - 419.68 kcal/mol) and greater than that of extremely unstable Ba(Ⅱ)-exchanged zeolite A($Ba_{6-}$A: - 324.01 kcal/mol). All the data of powder X-ray diffraction, infrared and Raman spectroscopy of Co(Ⅱ)-exchanged zeolite A showed the evidence of instability of its framework in agreement with the theoretical calculation. Three different groups of water molecules are found in hydrated Co(Ⅱ )-exchanged zeolite A; W(Ⅰ) group of water molecules having only hydrogen-bonds, W(Ⅱ) group water coordinated to $Na^+$ ion, ans W(Ⅲ) group water coordinated to Co(Ⅱ) ion. The averaged interaction energy of each water group shows the decreasing order of W(Ⅲ)>W(Ⅱ)>W(Ⅰ).

• Elastomers and Composites
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• v.57 no.1
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• pp.1-8
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• 2022

In this study, the photo-deposition method was used to introduce Ag onto the surface of TiO₂ to synthesize an Ag-TiO₂ composite. The effects of the varying amounts of AgNO₃ precursor and annealing time periods on the Ag content in the composites, as well as their antibacterial characteristics under visible light conditions were studied. SEM analysis revealed the spherical morphology of the Ag-TiO₂ composite. Compared with TiO₂, the Ag particles were too small to be observed. An XPS analysis of the Ag-TiO₂ surface confirmed the Ag content and showed the peak intensities for elements such as Ag, Ti, O, C, and Si. The highest Ag content was observed when 33.3 wt.% of AgNO₃ and an annealing time of 6 h were employed; this was the optimum annealing time for Ti-Ag-O bonding, in that the lowest number of O bonds and the highest number of Ag bonds were confirmed by XPS analysis. Superior antibacterial properties against Bacillus and Escherichia coli, in addition to the widest inhibition zones were exhibited by the Ag-TiO₂ composite with an increased Ag content in a disk diffusion test, the bacterial reduction rate against Staphylococcus aureus and Escherichia coli being 99.9%.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1859-1864
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• 2011

Two lanthanide complexes, $[Ln(NO_3)_2(H_2O)_3(L)_2](NO_3)(H_2O)$ {Ln = Eu (1), Tb (2); L = 2-(4-pyridylium)-ethanesulfonate, $(4-pyH)^+-CH_2CH_2-SO_3^-)$}, were prepared from lanthanide nitrate and 4-pyridineethanesulfonic acid in $H_2O$ under microwave-heating conditions. Complexes 1 and 2 are isostructural, and the lanthanide metal in both complexes is coordinated to nine oxygen atoms. The pyridyl nitrogen in the ligand is protonated to give a zwitter ion that possesses an $NH^+$ (pyridyl) positive end and an $SO_3^-$ negative end. All O-H and N-H hydrogen atoms participate in hydrogen bonds to generate a two-dimensional (complex 1) or a three-dimensional network (complex 2). Complex 1 exhibits an intense red emission, whereas complex 2 exhibits an intense green emission in the solid state at room temperature.

• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.739-743
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• 2006

Synthesis of cholic acid-based tripodal receptor (1) and its high chloride ion affinity in comparison with that of chenodeoxycholic acid (2) and lithocholic acid-based receptor (3) was achieved. Anion binding affinities of the receptors were evaluated $by\;^1H$ NMR and ITC titrations. Tripodal receptor 1 showed a selective affinity for $CI ^-$ over $Br ^-$, $I^-$, $H_2 PO _4\;^-$, and $CH _3 CO_2\;^-$. The selectivity of 1 for $CI ^-$ is about 3 times that of $Br ^-$, and 17 times that for $H_2 PO_4\;^-$.

• Journal of applied mathematics & informatics
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• v.31 no.5_6
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• pp.595-608
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• 2013

Let G = (V, E) be a simple connected graph. The sets of vertices and edges of G are denoted by V = V (G) and E = E(G), respectively. In such a simple molecular graph, vertices represent atoms and edges represent bonds. The distance between the vertices $u$ and $v$ in V (G) of graph G is the number of edges in a shortest path connecting them, we denote by $d(u,v)$. In graph theory, we have many invariant polynomials for a graph G. In this paper, we focus on the Schultz polynomial, Modified Schultz polynomial, Hosoya polynomial and their topological indices of a molecular graph circumcoronene series of benzenoid $H_k$ and specially third member from this family. $H_3$ is a basic member from the circumcoronene series of benzenoid and its conclusions are base calculations for the Schultz polynomial and Hosoya polynomial of the circumcoronene series of benzenoid $H_k$ ($k{\geq}3$).