Synthesis and Crystal Structure of a Cobalt(Ⅱ) Coordination Polymer with Benzene-1,3,5-triacetate and 1,2-Di(pyridin-4-yl)ethene

A novel coordination polymer, [Co3（bta）2（dpe）3（H2O）2]·2H2O （1, H3bta = benzene-1,3,5-triacetic acid, and dpe = 1,2-di（pyridin-4-yl）ethene）, has been hydrothermally prepared and characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction. The crystal is of triclinic system, space group P , with a = 9.5687（15）, b = 11.2470（17）, c = 13.686（2） , α = 78.262（3）, β = 89.271（4）, γ = 81.292（3）°, V = 1425.2（4） 3, C60H56N6O16Co3, Mr = 1293.90, Dc = 1.508 g/cm3, F（000） = 667, μ = 0.940 mm-1 and Z = 1. The final R = 0.0707 and wR = 0.1413 for 4950 observed reflections （I 2σ（I））. In the title complex, the bta ligand acts as a four-dentate bridging ligand to link up cobalt atoms into lamellar frameworks which are further interlinked by the dpe ligands to generate a trinodal （3,4,6）-connected （4.62）2（42.68.83.102）（64.82） net.

Synthesis,Structure,Fluorescent Property and Natural Bond Orbital(NBO) Analysis of a One-dimensional Cobalt(III) Complex Containing 1,3-Benzenedicarboxylate and 2-Methyldipyrido[3,2-f:2',3'-h]quinoxaline Ligand

A novel metal-organic coordination polymer [Co（m-BDC）（Medpq）·2H2O]n（m-H2BDC = benzene-1,3-dicarboxyalic acid,Medpq = 2-methyldipyrido[3,2-f：2＇,3＇-h]quinoxaline） has been hydrothermally synthesized and structurally characterized by elemental analysis,IR spectrum and single-crystal X-ray diffraction.The title compound crystallizes in monoclinic,space group C2/c with a = 19.986（4）,b = 15.789（3）,c = 16.292（3）（A°）,β = 126.54（3）°,V = 4130.3（14）（A°）^3,C23H18N4O6Co,Mr = 505.34,Dc = 1.625 g·cm^-3,Z = 8,μ = 0.883 mm^-1,F（000） = 2072,the final R = 0.0772 and wR = 0.1428.The crystal structure of complex 1 is an infinite zigzag-like chain of hexacoordinate Co^3＋ ions,in which the Co^3＋ ions are bridged in two coordination modes by m-BDC^2＋ ligands and decorated by Medpq ligands,showing a slightly distorted octahedral geometry.Additionally,the compound shows strong fluorescence in the solid state at room temperature.Natural bond orbital（NBO） analysis is performed by using the NBO method built in Gaussian 03 Program.The calculation results show a covalent interaction between the coordinated atoms and Co^3＋ ions.

Two 3D Metal-organic Frameworks with 4-Fold [2＋2]-type Interpenetrated hms Nets Based on a Flexible Tricarboxylic Acid

Two 3D 4-fold interpenetrated metal-organic frameworks, [Mn（L）（bpy）]n （1） and [Cu（HL）（bpy）]n （2）（H3L = 4,4＇,4＇＇-（benzene-1,3,5-triyl-tri（methyleneoxy）） tribenzoic acid, bpy = 4,4′-bipyridine）, were synthesized under hydrothermal conditions, and characterized by element analyses, IR spectra, thermogravimetric analyses, X-ray powder diffraction and magnetic property studies. The single-crystal X-ray analyses revealed that 1 and 2 are homogeneous. 1 crystallizes in monoclinic, space group Cc with a = 26.794（2）, b = 11.6346（10）, c = 21.4614（18） ？, β = 91.570（2）°, V = 6687.9（10） A^3, Z = 8, Mr = 736.59, D = 1.463 g·cm^（-3）, μ = 0.458 mm^-1c, R（int） = 0.0524, F（000） = 3040, the final R = 0.0844 and wR = 0.2266 for 8092 observed reflections（I 〉 2σ（I））. 2 crystallizes in monoclinic, space group Cc with a = 27.609（12）, b = 11.126（10）, c = 21.490（9） ？, β = 92.131（2）°, V = 6597（5） A^3, Z = 8, Mr = 746.21, Dc = 1503 g·cm^（-3）, μ = 0.726 mm^-1, R（int） = 0.0542, F（000） = 3080, the final R =0.0681 and wR = 0.1831 for 6777 observed reflections（I 〉 2σ（I））. Two compounds are 3D [2＋2]-type 4-fold interpenetrated frameworks with（6^3）（6^9.8） hms topology. The magnetic study of compound 2 shows the presence of weak antiferromagnetic interaction between the Cu^Ⅱ ions in 2.

Co－fluorescence Enhancement System Based on Lanthanum（Ⅲ） for Determination of Terbium（Ⅲ）

The phenomenon of fluorescence enhancement for the system of terbium( Ⅲ ) with trimesic acid [ ben-zene-1, 3, 5-tricarboxylic acid (TMA)] in the presence of an excase of La￣(3+) in gelatin aqusous solution wasstudied. The fluorescence intensity of Tb￣Ⅲ -TMA system can be greatly increased by La￣(3+) , which causedthe largest enhancement of the fluorescence intensity over two orders of magnitude. The intermolecular transfer of energy was responsible for the mechanism of the fluorascence enhancement. Gelatin plays animportant role for the stabilization of the system. The system, having the maximum excitation and emis-sion wavelengths at 260 nm and 549 nm, respectively, shows a constant fluorescence interisity over the pHrange 4～6. The fluorescence intensity is a linear function of Tb￣(3+) concentration in the range of 8. 0 ×10 ￣(-9)～ 2. 6 × 10￣(-7) mol· L￣(-1) and the limit of detection is 2.0 × 10￣(-9) mol·L￣(-1) . The optimized procedurewas used for the determination of trace amount of terbium in rare earth oxides and international standardreference rocks with satisfactory results.