| In recent years, a considerable interest has been focused on the novel coordination polymers because of their fascinating structural and topological features, and their potential application in functional materials and molecular recognition. Pyrazine-2,3-dicarboxylic acid is a polydentate organic ligand containing N, O atoms, which can coordinate to several metal ions and may exhibit various coordination modes. Thus it is a good candidate for synthesizing novel complexes. In this thesis six rare earth complexes and six transition metal complexes have been synthesized using pyrazine-2,3-dicarboxylic acid (H2pzdc) as ligand, which were characterized by elemental analysis, infrared (IR) spectroscopy, and single crystal X-ray diffraction. The thermogravimetric analysis (TGA) and fluorescent properties of some of these compounds were also investigated. Main work is summarized below.1. Six rare earth complexes [Ce2(C6H2N2O4)3(H2O)]n (1), [Sm2(C6H2N2O4)3(H2O)2]n·nH2O (2),[Dy2(C6H2N2O4)3(H2O)5]n·2nH2O(3), [Er2(C6H2N2O4)3(H2O)7]n·4nH2O (4), [Yb2(C6H2N2O4)2 (H2O)6]n·4nH2O·2CH3OH (5) and [Lu2(C6H2N2O4)2(H2O)6]n·6nH2O (6) have been synthesized by the solvothermal reactions of pyrazine-2,3-dicarboxylic acid with rare earth salt. Complexes (1) and (2) are three-dimensional coordination polymers. They crystallize in the monoclinic system, space group P21/c, with a = 8.9559(5) (?), b = 16.9415(10) (?), c = 15.4905(9) (?),β= 101.412(1)°,for complex (1) and a = 8.8496(3)(?), b = 16.7885(6)°(?), c = 15.3105(5) (?),β= 101.0130(10)°for complex (2). The Ln(III) ions in complexes (1) and (2) are nine-coordinated in a distorted monocapped square-antiprismatic geometry. The pyrazine-2,3-dicarboxylate ligand adoptsμ5-O,O,O,O,N andμ4-O,O,O,N bridging mode. Complexes (3) and (4) dispaly two-dimensional network structure. Complex (3) crystallizes in the monoclinic system, space group P21/n, with a = 17.300(2) (?), b = 6.6223(13) (?), c = 23.504(3) (?),β= 93.684(2)°. Complex (4) crystallizes in the monoclinic system, space group P21, with a = 7.9900(10) (?), b = 27.398(3) (?), c = 14.407(2) (?),β= 90°. The Ln(III) ions in complexes (3) and (4) are eight-coordinated in distorted square-antiprismatic geometries. The pyrazine-2,3-dicarboxylate ligand adopts aμ3-O,O,N bridging mode. Complexes (5) and (6) are one-dimensional coordination polymers. They crystallize in the monoclinic system, space group P21, with a = 7.5392(13) (?), b = 6.5558(10) (?), c = 14.0059(18) (?),β=105.008(2)°for (5) and a = 7.4856(13) (?), b = 6.5048(10) (?), c = 13.8869(18) (?),β= 104.7680(10)°for (6). The Ln(III) ions in complexes (5) and (6) are eight-coordinated in distorted square-antiprismatic geometries. There are some free methanol molecules in complex (5). The pyrazine-2,3-dicarboxylate ligand adopts aμ4-O,N,O,O bridging mode. Luminescent studies on (2) and (3) showed that the pzdc2- ligand can act as an"antenna"to sensitize the fluorescence of lanthanide metal centers.2. An unexpected coordination polymer [Zn2(C12H8N2)2(C2O4)2]n (7) and one expected coordination polymer [Zn8(C6H2N2O4)8(C10H10N2)4·8H2O]n·5nH2O (8) have been synthesized by the solvothermal reactions of zinc salt with pyrazine-2,3-dicarboxylic acid in the presence of 4,4'-bpy or phen. Complex (7) is a one-dimensional coordination polymer. It crystallizes in the monoclinic system, space group P21, with a = 9.1131(10) (?), b = 13.6751(14) (?), c = 10.1705(12) (?),β= 93.3470(10)°. Complex (8) is a two-dimensional coordination polymer. It crystallizes in the orthorhombic system, space group Pccn, with a = 9.9356(14) (?), b = 35.356(3) (?), c = 7.1357(10) (?),β=9 0°.The zinc ions in complexes (7) and (8) are six-coordinated in distorted octahedral geometries. Luminescent studies on (7) and (8) showed that the emission of complex (7) and (8) are assigned to the emission of ligand-to-metal charge transfer(LMCT).3. Two reported coordination polymers {[Cd(C6H2N2O4)(C12H8N2)]n·nH2O (9) and [Cd2(C6H2N2O4)2 (C10H10N2)·2H2O]n (10), two unreported coordination polymers [Cd2 (C6H2N2O4)2 (C10H10N2)2]n·4nH2O (11) and [Cd(C6H2N2O4) (C10H10N2)2]n·nH2O (12)} have been synthesized by the solvothermal reactions of cadmium salt with pyrazine-2,3-dicarboxylic acid in the presence of phen, 4,4'-bpy or 2,2'-bpy. Complex (11) is a three-dimensional coordination polymer. Its crystallizes in the monoclinic space group Cc with a = 20.263(2) (?), b = 11.8247(10) (?), c = 14.8053(15) (?),β= 102.505(2)°; Complex (11) crystallizes in the monoclinic system, space group P21/c, with a = 10.8435(14) (?), b = 14.5235(19) (?), c = 10.3096(10) (?),β= 98.507(2)°. There are two cadmium ions with different coordination geometries in the asymmetric unit of complex (11). One cadmium ion is seven-coordinated in a distorted pentagonal bipyramidal geometry. The other one is six-coordinated in a distorted octahedral geometry. The Cadmium ions in complex (12) are six-coordinated in distorted octahedral geometries. Luminescent studies on (9), (10) and (11) showed that their emissions are assigned to the emission of ligand-to-metal charge transfer (LMCT). There are only small differences in the emissions of complexes (9), (10) and (11). Luminescent studies on (12) showed that its emission is related to theπ*→πtransition in 2,2'-bpy.
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