Ya-Hui Zhao

pH-dependent self-assembly of divalent metals with a new ligand containing polycarboxylate: syntheses, crystal structures, luminescent and magnetic properties

Six new coordination polymers, namely, [Cd(HL)(4,4′-bpy)(H2O)]·H2O (1), [Cd3(L)2(4,4′-bpy)3(H2O)]·2.5H2O (2), [Co(HL)(4,4′-bpy)]·H2O (3), [Co2(L)(4,4′-bpy)0.5(μ3-OH)(H2O)2]·H2O (4), [Zn(HL)(BIMB)]·2H2O (5), [Zn3(L)2(BIMB)2]·3H2O (6), where H3L = 5-(4-carboxybenzyloxy)isophthalic acid, 4,4′-bpy = 4,4′-bipyridine, BIMB = 1,4-di(1H-imidazol-1-yl)benzene, have been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction. In complexes 1, 3 and 5, H3L ligand is partially deprotonated in the form of HL2−; while in 2, 4 and 6, it is completely deprotonated due to the influence of different pH values. Complexes 1 and 5 are 2D layer structures, the hydrogen bonds between lattice-water molecules and carboxylate groups of HL2− ligands extend the 2D layer into a 3D framework; while complex 3 is a 3D framework with α-Po topology. Complex 2 is a 3D fourfold interpenetrating (3,4,4)-connected net with (63)(62·84)(64·82) topology. Complex 4 is a twofold interpenetrating (3,8)-connected net with (43)2(46·618·84) topology. And complex 6 is a twofold interpenetrating (3,4,6)-connected net with (4·62)(64·72)(42·66·74·8·92) topology. In addition, powder X-ray diffraction and thermogravimetric analyses for 1–6, photoluminescent properties for 1, 2, 5, 6 and magnetic properties for 3, 4 are investigated in detail.

Molecular tectonics of metal–organic frameworks based on ligand-modulated polynuclear zinc SBUs and aromatic multicarboxylic acids

An investigation into the molecular tectonics of metal–organic frameworks (MOFs) is reported on the basis of N-donor ligand modulated polynuclear zinc clusters and different aromatic polycarboxylic ligands. A series of three-dimensional (3D) coordination frameworks, [Zn2(BDC)1.5(L)(OH)]·H2O (1), [Zn2(BOABA)(L)(OH)]·2H2O (2), [Zn2(BOABA)(L)(OH)]·4H2O (3), [Zn3(BTC)2(OH)]·0.25H2O·[N(C4H9)4] (4) and [Zn2(BTEC)0.5(L)(OH)2] (5), were synthesized by self-assembly of zinc ions with a new N-donor ligand 4,5-diazafluoren-9-oxime (L) and the aromatic polycarboxylic ligands 1,4-benzenedicarboxylic acid (H2BDC), 3,5-bis-oxyacetate-benzoic acid (H3BOABA), 1,3,5-benzenetricarboxylic acid (H3BTC), and 1,2,4,5-benzenetetracarboxylic acid (H4BTEC). Compound 1 exhibits a twofold interpenetrated α-polonium-type network based on tetranuclear Zn clusters as six-connected vertices and BDC ligands as linkers. Compound 2 also consists of tetranuclear units, it shows a (3,6)-connected rutile network, where tetranuclear zinc clusters act as six-connected nodes and BOABA ligands act as three-connected nodes. Compound 3 is an isomer of compound 2, due to the different configuration of tetranuclear zinc, it displays a novel (3,6)-connected network with a complex (4·62)2(42·69·84) topology. In 4, the connection between the trinuclear zinc clusters and the BTC ligands results in an infinite 3D (3,6)-connected network with point symbol (4·62)(63)(4·611·83). Compound 5 constitutes a lvt net, which is built from tetranuclear clusters and BTEC as four-connected nodes, respectively. The results indicate that various polynuclear zinc clusters are modulated by L ligands combining with Zn atoms via chelation or monodentate coordination, or acting as a structure-directing agent. Meanwhile, aromatic multicarboxylic acids also play important roles in the construction of the compounds with various structures.

Three novel 3D (3,8)-connected metal–organic frameworks constructed from flexible-rigid mixed ligands

Three novel 3D (3,8)-connected networks, namely [Cd2(L1)2(1,3-bdc)] 1, [Cd2(L2)2(1,4-bdc)]·3H2O 2 and [Cd3(L3)2(1,3-bdc)2] 3, where L1 = 3,5-bis(pyridin-4-ylmethoxy)benzoic acid, L2 = 3,4-bis(pyridin-4-ylmethoxy)benzoic acid, L3 = 3,5-bis(pyridin-3-ylmethoxy)benzoic acid, bdc = benzenedicarboxylate, have been synthesized hydrothermally and characterized. Complex 1 exhibits a twofold interpenetrating network constructed from Cd2-based secondary building units (SBUs) [Cd2(CO2)2O2N4] with (42·6)2(44·622·82) topology. Complex 2 is constructed from Cd2-based SBUs [Cd2(CO2)4N4] with (43)2(46·618·84) topology. The structure of 3 is based on linear Cd3-based SBUs [Cd3(CO2)6N2] with a Schlafli symbol (42·5)2(44·56·610·75·82·9). In addition, X-ray powder diffraction (XRPD) and luminescent properties of 1–3 were also investigated in detail.

Synthesis, Crystal Structure and Spectroscopic Studies of a Supramolecular Compound [Cu(IDA)(phen)(H2O)]·4H2O Built from π–π Interactions and Hydrogen Bonds

The stoichiometric reaction of (MeCOO)2Cu, iminodiacetic acid (H2IDA) and 1,10-phenanthroline (phen) in H2O yields the novel complex [Cu(IDA)(phen)(H2O)]·4H2O (1). An X-ray structural determination shows that the dimer was formed by diverse hydrogen bonding and π–π interactions, and that each metal CuII center is six-coordinate, exhibiting an octahedral coordination. The complex was also characterized by t.g.a., FT–IR and u.v.–vis. spectroscopy and the electrochemical behavior of (1) was also studied. Its electronic spectra have been calculated by the CIS method.

A novel two-dimensional zinc(II) coordination polymer with 6-mercaptonicotinic acid.

The novel title Zn(II) coordination polymer, poly[bis(mu-6-thioxo-1,6-dihydropyridine-3-carboxylato-kappa(2)S:O)zinc(II)], [Zn(C6H4NO2S)2]n, consists of two crystallographically independent zinc centers and two 6-mercaptonicotinate (Hmna-) ligands. Each Zn(II) atom is four-coordinated and lies at the center of a distorted tetrahedral ZnS2O2 coordination polyhedron, bridged by four Hmna- ligands to form a two-dimensional (4,4)-network. Each Hmna- ion acts as a bridging bidentate ligand, coordinating to two Zn(II) atoms through the S atom and a carboxyl O atom. The metal centers reside on twofold rotation axes. The coordination mode of the S atoms and N-H...O hydrogen-bonding interactions between the protonated N atoms and the uncoordinated carboxyl O atoms give the extended structure a wavelike form.