Studies On The Hydrothermal Reactions Of Substituted 1,2,4-Triazole With Metal Ions And The Structure ,Fluorescence Properties Of Their Complexes

In recent years, the synthesis, crystal structures and properties of metal coordination compounds of 1,2,4-triazoles become one of the extensive research subjects in the fields of coordination chemistry, due to their important functions in the fields of pharmaceutic,argricultral chemicals as well as molecular materials. In this dissertation, the studies on the Zinc and Cadmium coordination compounds of 1,2,4-triazoles have been reviewed in detail. Eight new coordination polymers have been synthesized by the hydrothermal reaction. They were studied by IR, Elemental Analysis and single crystal X-ray diffraction methods.The fluorescence spectra data of several complexes are measured. Four 3-D coordination polymers {CdCl(AmTAZ)}_n(1) ,{CdBr(AmTAZ)}_n(2) {CdSO₄(HAmTAZ)}_n(3) and {Cd₂(AmTAZ)₃(C₂O₃)}_n(4) (HAmTAZ:3-amino-1,2,4-triazole) have been synthesized by hydrothermal reaction of 5-amino-1H-1,2,4-triazole-3-carboxylic acid with corresponding cadmium salt at 160℃,160℃,170℃and 160 ℃for 7 days, respectively. The complex (1) crystallizes in orthorhombic space group P2₁2₁2₁ with cell parameters a=6.406(4)A, b=7.786(5)A, c=10.379(6)A, α=90°, β=90°, γ=90°, V=517.7(5)A³, Z=4. The complex (2) crystallizes in orthorhombic space group P2₁2₁2₁ with cell parameters a=13.973(4)A, b=6.6440(17)A, c=6.7133(17)A, α=90°, β=90°, γ=90°,V=623.2(3)A3, Z=4. The complex (3) crystallizes in orthorhombic space group Pba2 with cell parameters a=13.973(4)A, b=6.6440(17)A, c=6.7133(17)A, α=90°, β=90°, γ=90°, V=623.2(3)A³, Z=4. The complex (4) crystallizes in monoclinic space group C2/c with cell parameters a=11.768(3)?, b=16.835(4)?, c=7.9540(17)?, α=90°, β=90.765(10)°, γ=90°, V=1575.7(6)?3, Z=4. Complexes (1) and (2) are isostructural. The fundamental structural units of the complexes contain one Cd(â…¡) center, four triazole-bridged ligands and two μ2-X(X=Cl,Br) ligands. Each mononuclear unit is connected to nine other units through four μ4-AmTAZ ligands and two μ2-X ligands to result in a 3-D framework. In complex (3), four neighboring Cd2+ centers in the ab plane are connected by μ4-bridging SO42-anions and the nitrogen atoms of 2-and 4-position in the triazole(TAZ) ring are coordinated to different Cd2+ centers along the c-axis, thus generating a 3-D framework. Complex (4) contains a dinuclear Cd(â…¡) unit. Cd(1) and Cd(2) centers are linked together by one triazole ligand. The complex (4) exhibits a 3-D network structure. Two 2-D coordination polymers {ZnCl(AmTAZ)}n(5) and {Zn(CH3COO)(AmTAZ)}n(6) have been synthesized by hydrothermal reaction of 5-amino-1H-1,2,4-triazole-3-carboxylic acid with ZnCl2 and Zn(CH3COO)2 at 170℃and 140℃, respectively, for 7 days. The complex (5) crystallizes in orthorhombic space group Pbca with cell parameters a=15.678(8)?, b=9.450(5)?, c=9.782(5)?, α=90°, β=90°, γ=90°, V=1449.3(13)?3, Z=8. The complex (6) crystallizes in orthorhombic space group Pccn with cell parameters a=15.678(8)?, b=9.450(5)?, c=9.782(5)?, α=90°, β=90°, γ=90°, V=1449.3(13)?3, Z=8. Complex (5) and (6) are isostructural. Both exhibit a 2-D network structure. Furthermore, the adjacent 2-D networks are connected together through hydrogen bonding interactions to form 3D-networks. Two novel 3-D coordination polymers {Zn4(AmTAZ)4SO4(OH)(C2O4)0.5}n(7) and {[Zn5(AmTAZ)6(OH)3]NO3·2H2O}n(8) have been synthesized by hydrothermal reaction of 5-amino-1H-1,2,4-triazole-3-carboxylic acid with ZnSO4 and Zn(NO3)2 at 170℃and 160℃, respectively, for 7 days. The complex (7) crystallizes in monoclinic space group C2/m with cell parameters a=18.5934(12)?, b=17.9100(11)?, c= 7.4267(5)?, α=90°, β=96.3020 (10)°, γ=90°, V=2458.2(3)?3, Z=4. The Complex (8) crystallizes in Cubic space group Pa 3? with cell parameters a=15.053(18)?,b=15.053(18)?, c=15.053(18)?, α=90°, β=90°, γ=90°, V=1449.3(13)?3, Z=8.The Complex (7) contains different coordination environment of three zinc ions. The neighboring Zn2+ centers are linked by the triazole ligand. In complex (7), different Zn(â…¡) ions are linked by the bridging ligands of AmTAZ, SO42-,OH-and C2O42-to form 2D layer structure in the ab plane. The adjacent layers are connected together through the triazole-bridging ligand along the c direction to form a 3D layer structure. In complex (8), the Zn2+ ions are linked by the nitrogen atoms of the triazole ligands, and The Zn1 and Zn3 centers are connected by μ2-bridging OH-anion, thus forming an infinite 3D framework. The four complexes (1),(2),(7) and (8) show the strongest fluorescence with λem=528nm(λex=460nm,(1)) ,λem=438nm(λex=292nm,(2)) ,λem=420nm(λex=299nm, (7)) and λem=569nm(λex=414nm,(8)) in the solid state at room temperature. The emission observed in the complexes are tentatively assigned to the ligands fluorescence(LLCT).