Synthesis, Structure and Luminescence Property of Transition Metal Complexes with 1,3-Di(4-pyridyl)-propane and 1,2-Benzenedicarboxylic

Taking 1,3-di(4-pyridyl)-propane(bpp) and 1,2-benzenedicarboxylic acid(1,2-H(2)bdc) as ligands, three new transition metal complexes, M-2(1,2-bdc)(2)(bpp)(2) center dot 2H(2)O [ M(II)= Co(1), Ni(2)] and Cd(1,2-bdc)(bpp) center dot H2O(3), were obtained-Complexes 1 and 2 crystallize in monoclinic crystal system with space group P2(1) and show 3D structures with {6(5) center dot 8} topology. There are two M(II) centers with the similar coordination environments in complexes 1 and 2. Each M(II) center is six-coordinated to three oxygen atoms from two 1,2-bdc ligands, two nitrogen atoms from bpp ligands and one water molecule in a distorted octahedral arrangement. The 1,2-bdc ligand adopts monodentate bridging/bidentate chelating mode to link two metal centers to form M1-(bpp)-M1 right-handed-helical chain.The bpp ligand adopts Trans-Gauche(TG) conformation and connects adjacent M(II) centers to form M1-(bpp)-M1and M2-(bpp)-M2 chains. These three kinds of chains are woven together to form a 3D framework-Complex 3 crystallizes in monoclinic crystal system with space group P2(1)/c and shows a 2D structure. The Cd(II) is in distorted pentagonal bipyramidal polyhedron with four oxygen atoms of two 1,2-bdc ligands, two nitrogen atoms of bpp ligand and one water molecule. The 1, 2-bdc ligand adopts bi (bidentate chelating) mode to link Cd (II) centers to form Cd-(1,2-bdc)-Cd chain. The bpp ligand adopts TG conformation and connects Cd (II) centers to form Cd-(bpp)-Cd chain. The two kinds of chains with shared Cd(II) are alternately arranged to form a 2D struc-ture. Complex 3 shows strong ligand-based fluorescence with maximum emission at 408 nm, which is attributed to pi*-pi transition of the ligands-Different organic small molecules have different effects on the fluorescence intensity of complex 3, and aniline has a significant quenching effect, thus complex 3 can be used for the se-lective detection of aniline through fluorescence quenching mechanism.