Shu-Ting Wu

A series of novel Pb(II) or Pb(II)/M(II) (M = Ca and Sr) hybrid inorganic–organic frameworks based on polycarboxylic acids with diverse Pb–O–M (M = Pb, Ca and Sr) inorganic connectivities

Solvothermal reactions of Pb(NO3)2 with aromatic polycarboxylic acids and the alkaline or alkaline earth metal nitrates led to six novel homo- or heterometallic lead(II)/carboxylate inorganic–organic hybrid materials, [Pb(p-BDC)(μ2-DMSO)] (1), [PbCa(m-BDC)2(μ1-DMSO)] (2), [PbCa(OH-m-BDC)2(CH3OH)2] (3), (Me2NH2)[PbSr(OH-m-BDC)(O-m-BDC)] (4), [Pb(SDBA)] (5), and [PbCa(SDBA)2(μ1-DMSO)2] (6) (p-H2BDC = 1,4-benzenedicarboxylate, m-H2BDC = 1,3-benzenedicarboxylate, OH-m-H2BDC = 5-hydroxy-1,3-benzenedicarboxylate, and H2SDBA = 4,4′-sulfonyldibenzoic acid). These hybrids have been fully characterized by single crystal X-ray diffraction, XRD, TGA, IR, UV-vis, elemental analysis and photoluminescence spectra. They are all three-dimensional structures except for 6, which displays a 2D layer structure. Topology analysis reveals that complexes 1–6 manifest dia, pcu, sne, hex, sev, and (4,4)-topological nets, respectively. Moreover, they exhibit diverse inorganic connectivities which have not been observed for the lead(II)/carboxylate systems, e.g. the 1D Pb–O–Pb chains in 1 and 5, the 2D Pb–O–Ca layer in 2, the 1D Pb–O–Sr chain in 4, and the 1D Pb–O–Ca chains in 3 and 6. The luminescent properties of these hybrid materials, the NLO property of 3 as well as the methane sorption property of 5 have also been investigated.

Enantioselective Synthesis of a Chiral Coordination Polymer with Circularly Polarized Visible Laser

Circular dichroism is known to be the feature of a chiral agent which has inspired scientist to study the interesting phenomena of circularly polarized light (CPL) modulated molecular chirality. Although several organic molecules or assemblies have been found to be CPL-responsive, the influence of CPL on the assembly of chiral coordination compounds remains unknown. Herein, a chiral coordination polymer, which is constructed from achiral agents, was used to study the CPL-induced enantioselective synthesis. By irradiation with either left-handed or right-handed CPL during the reaction and crystallization, enantiomeric excesses of the crystalline product were obtained. Left-handed CPL resulted in crystals with a left-handed helical structure, and right-handed CPL led to crystals with a right-handed helical structure. It is exciting that the absolute asymmetric synthesis of a chiral coordination polymer could be enantioselective when using CPL, and provides a strategy for the control of the chirality of chiral coordination polymers.

Two enantiomorphic 3D Zn(II)–carboxylate MOFs with double helical structures serving as a chiral source induced by hydrogen bonding

Two enantiomorphic 3D Zn(II)–carboxylate metal–organic frameworks [Zn(bpydc)(H2O)2] (1M and 1P) (H2bpydc = 2,2′-bipyridyl-5,5′-dicarboxylic acid) have been synthesized. They both contain an elegant double helix, self-organized through hydrogen bonds between the coordinated water molecules and uncoordinated carboxylate oxygen atoms. This double helical structure serves as a chiral source which transmits chiral information over the whole 3D framework.

Structural variation from 1D to 3D: effect of metal centers on the construction of metal–organic coordination polymers with N-(1H-tetrazol-5-yl)benzamide ligand

A new multifunctional semirigid acylamide ligand comprising a tetrazole ring, N-(1H-tetrazol-5-yl)benzamide (HL), has been synthesized, with which five coordination polymers of different metal ions, namely, CdL2 (1), AgL (2), MnL2 (3), CuL2 (4), PbL2 (5), have been prepared and characterized by elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction. The X-ray diffraction analysis reveals that compound 1 crystallized in a chiral space group and is a 3D non-interpenetrated diamondoid framework with Cd(II) centers in tetrahedral geometry. Compound 2 is a 2D coordination polymer with a 3-connected 4·82-fes topology. Compounds 3 and 4 are isomorphous, and both of them exhibit an interesting 2D 44-sql network while compound 5 shows 1D zigzag chains. Thermal stabilities, photoluminescence and NLO properties have also been studied.

Synthesis, structures and luminescent properties of new Pb(II)/M(I) (M = K, Rb and Cs) frameworks based on dicarboxylic acids: a novel icosahedral Pb6-M6 SBU

Reactions of Pb(CH3COO)2·3H2O, MNO3 (M = K, Rb, and Cs) with m-H2BDC (1,3-H2BDC = 1,3-benzenedicarboxylic acid) in a mixed-solvent of DMF and methanol (v/v = 2/1) resulted in the formation of novel metal–organic frameworks [(Me)4N]2[Pb6M6(m-BDC)9(OH)2]·H2O (1: M = K; 2: M = Rb; 3: M = Cs). With H2SDBA (H2SDBA = 4,4′-sulfonyldibenzoic acid), two new lead(II) coordination polymers, [K2Pb(SDBA)2(μ3–H2O)]·3H2O (4) and [Cs2Pb2(SDBA)3(DMF)] DMF (5), were isolated. These complexes have been fully characterized by elemental analysis, PXRD, FTIR, TGA and single crystal X-ray diffraction. Compounds 1–3 are 3-D coordination frameworks built by a novel 12-metal heterometallic Pb6-M6 cage that extends topologically into an eight-connected hex network viaisophthalic acid ligands. Compounds 4 and 5 are new 3-D lead(II) MOFs constructed by ladder-like Pb(II)/K(I)/SDBA2− and rod-shaped Pb(II)/Cs(I)/SDBA2− motifs, respectively. The Pb(II) ions in these complexes show different coordination geometries with various coordination numbers (5, 7 and 9). In addition, an ideal T-shaped μ3-H2O is observed in 4. The SDBA2− ligands in 4 and 5 display three types of new coordination modes that have not been observed before. At room temperature, 1–3 exhibit strong emissions in the solid-state which can be attributed to ligand-to-metal charge transfer between the delocalized π bonds of carboxylate groups and p orbitals of lead(II) centers.

Syntheses and characterizations of two silver(I) coordination polymers constructed from bipyrazole and dicarboxylate ligands

Two silver(I) compounds, [Ag(H2mbpz)(Hchda)]n (1) and [Ag2(H2mbpz)2(oba)]n (2) (where H2mbpz = 3,3′,5,5′-tetramethyl-4,4′-bipyrazole, H2chda = trans-cyclohexane-dicarboxylic acid and H2oba = 4,4′-oxy-bis-benzoic acid), have been synthesized and characterized by single-crystal X-ray diffraction analyses. In both cases, the Ag(I) centers are linked by H2mbpz ligands to form 1-D Ag(I)-H2mbpz chains; then, the Ag(I)-H2mbpz chains connect with two neighboring congeners through Ag⋯Ag interactions, forming 2-D supramolecular layers. In 1, the dicarboxylate is monodeprotonated and linked to form an anion chain through strong hydrogen bonding interaction. Such anion chains attach on two sides of the supramolecular layers via Ag–O bonds to form a neutral sandwich-like layered network. In 2, the dicarboxylate is fully deprotonated and adopts a μ2-η1:η1 mode to link two adjacent supramolecular layers to form a twofold interpenetrating 3-D supramolecular network. The thermal stability and luminescence of 1 were also studied.