Font Size: a A A

Novel Topological Metal-organic Frameworks And Their Property Studies

Posted on:2008-02-22Degree:DoctorType:Dissertation
Country:ChinaCandidate:X W WangFull Text:PDF
GTID:1101360242997829Subject:Rock and mineral materials science
Abstract/Summary:PDF Full Text Request
Novel or new topological metal-organic frameworks 1-10 have been synthesized by hydrothermal reactions, and homochiral metal-organic framework 11 have been generated from self-assembly reaction under mild conditions. The compounds were characterized by elemental analysis, IR spectra, thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and single-crystal X-ray diffraction. The photofluorescence properties or magnetic properties have been studied.(1) Two metal-organic frameworks, [Zn2(ATA)3(ATA)2/2] (1) and [Zn(OH)(ATA)2] (2), have been synthesized by the hydrothermal reactions of Zn(Ⅱ) salts with HATA. Compound 1 crystallizes in the monoclinic group P21/m, with the cell parameters of a=10.3400(12), b= 19.931(2), c=10.3723(12)(?),β=119.8130(10)°,V=1854.6(4) (?)3, Z=4, R1=0.0543,wR2= 0.1584, S=1.069. Parallel to (010), the tetrahedrally coordinated Zn atoms of 1 are bridged by theμ2-ATA- into (6,3) topological networks, which are interlinked by the mirror plane symmetricμ2-ATA- ligands along [010] direction to form bilayer honeycomb feature. 1 displays a unique four-connected 2D bilayer (4363)-"hcb"topological network. Within the crystal structure of 1, the N-H…N hydrogen bonding interactions play a key role to form the unique framework. Along [010] direction, the 2D bilayers further pack into 3D porous supramolecular structure via strongπ…πstacking interactions between the neighbouring ATA- ligands. 1 possesses high thermal stability and shows strong blue fluorescence in the solid when excited at 320 run at room temperature. 1 may be a potential blue fluorescent material. Compound 2 crystallizes in the orthorhombic group Pbcm, with the cell parameters of a=6.3449(5),b=10.4301(7),c= 6.6211(5) A,V=438.17(6) A3,Z=4,R1=0.0200,wR2=0.0556,S=1.157.the tetra-coordinated Zn(Ⅱ) atoms of 2 are bridged by theμ2-ATA- ligands andμ2-OH groups into "sql" topology(2) Four novel lanthanide noninterpenetrating metal-organic frameworks formulated as [Ln(3,5-pdc)(C204)0.5(H2O)2]·H2O (Ln=Lu(Ⅲ), Gd(Ⅲ), Tm(Ⅲ) and Yb(Ⅲ) for complex 3-6, respectively; 3,5-pdc=3,5-pyridinedicarboxylate) have been synthesized by hydrothermal reactions of 3,5-H2pdc with lanthanide oxide and perchloric acid. Crystal structural analysis indicates compound 3 crystallizes in the monoclinic group P21/c. The Lu atoms are bridged by the 3,5-pdc ligands into two-dimensional sheets parallel to (100), and the sheets are further bridged by the oxalate ligands into 3D metal-organic framework. Compound 3 shows a rare (3,4)-connected (4;82)(4;85)-"dmc"topological network, with the pdc and Lu acting as 3- and 4-connected centers and the oxalate ligands as simply links between the Lu nodes. Compounds 4 - 6 are isostructural and crystallize in the monoclinic group P21/n. Different from 3, the 3,5-pdc ligand in 4-6 acts as aμ4-bridge linking four metal ions through its four carboxylate O atoms and each metal ion connects four ligands to form a square lattice layers. The layers are interlinked by oxalate ligands into porous 3D metal-organic framework. Compounds 4-6 display the novel (4,5)-connected xww topology with the Schl(a|¨)fli symbol of (44.6.8)(44.62.84). The oxalate ligands were formed by lanthanide-based mediated CO2 in situ coupling under hydrothermal conditions. Compounds 4-6 exhibit strong fluorescence in the solid at room temperature, and may be used for fluorescent materials.(3) Hydrothermal reaction of MnCl2·4H2O with H3PTC (PTC= pyridine-2,4,6-tricarboxylate) yields a novel three-dimensional manganese(Ⅱ) clusters metal-organic framework, [Mn2(OH)(PTC)(H2O)] (7). Crystal structural analysis indicates compound 7 crystallizes in the triclinic group P(?), with the cell parameters of a=6.7169(7), b= 9.0656(8),c=9.1565(1)(?),α=74.930(7),β=74.262(8),γ=70.520(7)°, V=497.03(9) (?)3, R1= 0.0359, wR2=0.1621, S=1.185. The tetranuclear Mn(Ⅱ) clusters are linked by two carboxylate oxygen atoms into 1D chains along [001] direction. The resulting chains are further interlinked by carboxylate groups and PTC linkers into inorganic layers parallel to (010), inorganic-organic hybrid layers parallel to (101), respectively. The network topology can be simplified by considering just Mn4 clusters and the PTC ligands. Thus, the graphite (6,3) topological inorganic-organic layers are linked by the Mn-O-C-O-Mn jointers into three-dimensional framework, and the resultant network can be thought of as the 5-connected BN topology. Weak antiferromagnetic exchange interactions exists between the manganese(Ⅱ) ions in compound 7.(4) Three novel 3D metal-organic frameworks, [Zr6(μ4-O)(μ5-PTC)3(μ2-H2O)4.5]·Cl·0.6H2O (8·0.6H2O), [Zn6(μ4-O)(μ5-PTC)3(μ2-H2O)3]·Br (9) and [Zn3(μ5-PTC)2(μ2-H2O)2] (10), have been synthesized by the hydrothermal reactions of ZnX2·4H2O (X=C1, Br andⅠ) with H3PTC. Single crystal X-ray structural analyses revealed that 8 and 9 are isomorphic and crystallize in a triagonal space group R(?).Within the structure of compounds 8 and 9, the tetrahedral Zn4O cluster and Zn6 wheels are interlinked to form of inorganic zinc-oxygen scutellate layers parallel to (001), which can be considered as being constructed by the Zn54 hexagonal zinc-oxygen cluster SBUs and features as graphite (6,3) topological sheet with the Zn4O tetrahedral cluster cores acting as nodes. This kind of inorganic layers, consisting of Zn4O clusters and Zn6 wheel clusters, is unprecedented. The infinite zinc-oxide skeletons display four-connected "dia" topologies with the tetrahedral Zn4O cluster SBUs as nodes. Compound 10 crystallizes in an orthorhombic space group Pbcn, and displays the new and unusual (5,6)-connected 3D topological network, with the Schl(a|¨)fli symbol of(3;4;55;62;7)(32;4;56;66), where the PTC3-ligands act as 5-connected bridges. All the complexes exhibit strong blue fluorescence in the solid state at room temperature, and the frameworks show remarkable thermal stability. Compounds 8-10 may be used for blue-fluorescent materials.(5) A novel chiral two-fold interpenetrating three-dimensional porous metal-organic framework, [PbC1(C7H7N2O4)] (11), have been constructed from self-assembly o the flexible zwitterionic ligand N,N'-diacetic acid imidazolium chloride and Pb(NO3)2. Compound 11 crystallizes in a chiral tetragol space group I4122 (No.98),with the cell parameters of a= 11.9666(17), b=11.9666(17), c=15.485(3)(?), V= 2217.4(6)(?)3, Z=8, R1=0.0204, wR2= 0.0518, S=1.166. The metal-organic framework possesses right-handed helical rectangular channels with 41 helices running along c-axis. The infinitely right-handed helical chains are held by theμ2-chloride atoms into a 3D homochiral metal organic framework. The framework exhibits four-connected "dia" topological network when the zwitterionic ligands and C1 atoms are reduced to be simply bridges. Compound 11 adopts a doubly-fold interpenetrating structure to avoid the formation of very large open cavities, with the open channels constitute about 30.6% of the crystal volume. The interpenetrating 3D nets are topologically equivalent in terms of composition and configuration, which results in the homochiral framework. Compound 11 represents the first even number-fold interpenetrating three-dimensional chiral metal-organic framework constructed from the symmetrical flexible ligand without any chiral auxiliary.
Keywords/Search Tags:metal-organic frameworks, crystal structures, topologies, fluorescence properties, magnetic properties, thermal stability
PDF Full Text Request
Related items