Kou-Lin Zhang

Temperature and auxiliary ligand-controlled supramolecular assembly in a series of Zn(II)-organic frameworks: syntheses, structures and properties

Two temperature-dependent structures of 2D and 3D Zn(II)-organic frameworks (ZOFs) with a new 5-substituted benzene-1, 3-dicarboxylic ligand, 5-iodoisophthalic acid (H2IIP), and an auxiliary flexible ligand, 1,4-bis(1,2,4-triazol-1-yl)butane (btb), with different motifs, have been investigated. Results show that when the reaction was carried out at room temperature, a undulating 2D (4,4)-network, {[Zn(IIP)(btb)]·4H2O}n (1), which further extends into a novel “soft” 3D supramolecular microporous framework with two kinds of 1D nanochannels supported by face to face π⋯π stacking interactions and C–I⋯I halogen bonds, was generated. Under hydrothermal condition at 170 °C, however, a two-fold interpenetrated 3D framework with α-Po network topology, [Zn(IIP)(btb)]n (2), would be obtained. Interestingly, both the right- and left-handed 21 helical water chains lie in one kind of the nanochannels in 1. When the auxiliary ligand was replaced by a less flexible one with a shorter spacer length, 1,3-bis(1,2,4-triazol-1-yl)propane (btp), a novel temperature-independent single-walled discrete coordination tube, {[Zn(IIP)(btp)]·2H2O}n (3), was obtained at the same two temperatures. Inside the tube is found the 21 helical water chain. Interestingly, the reversible desorption/adsorption behavior to water is significantly observed in the frameworks 1 and 3. The framework 1 falls within the category of “recoverable collapsing” and “guest-induced re-formation” frameworks. The result shows their potential application as late-model water absorbents in the field of adsorption materials. Remarkably, the first discrete single-walled Zn(II) coordination tube 3 shows high framework stability and exhibits reversible desorption/adsorption to some small guest organic molecules (methanol, ethanol and isopropanol). Furthermore, these compounds exhibit blue fluorescence in the solid state.

Effect of N-donor auxiliary ligands on the engineering of crystalline architectures of a series of lead(II) complexes with 5-amino-2,4,6-triiodoisophthalic acid

The aqueous medium reactions of lead(II) nitrate with H2ATIBDC as a main ligand and bipy or biim as an auxiliary ligand lead to the two fascinating coordination polymers: [Pb(ATIBDC)(bipy)(H2O)]·3H2O (1) and [Pb(ATIBDC)(biim)]·H2O (2) [bipy = 2,2′-bipyridine, biim = 2,2′-biimidazole, and H2ATIBDC = 5-amino-2,4,6-triiodoisophthalic acid]. The interesting chiral three-dimensional (3D) network [Pb(ATIBDC)] (3) is obtained in the absence of any auxiliary ligands. Complex 1 is a one-dimensional (1D) helical chain, which further arrays into a 3D supramolecular metal–organic framework (MOF) with a 1D channel through the hydrogen-bonding and strong offset π⋯π stacking interactions. Furthermore, a 1D hydrogen-bonded helical water chain was found in 1. Interestingly, complex 1 exhibits reversible adsorption/desorption to water molecules. Framework 1 falls within the category of “recoverable collapsing” and “guest-induced re-formation” frameworks. Complex 2 features a fascinating 3D MOF. It displays a novel four-connected 4668-SOD (sodalite) zeotype network structure with 1D nanotubular channels. Complex 3 crystallizes in the chiral space group P31 and possesses a 3D honeycomb-like structure built up from a 1D Pb(II)-carboxylate-bridged helical chain with a 31 helix and ATIBDC2− ligand. The coordination modes of the ATIBDC2− ligand and crystalline architectures of the complexes are greatly dependent on the auxiliary ligands. The thermal stability and solid state fluorescent properties have been studied. Adsorption/desorption properties reveal that 2 may be used as an adsorbent material for some guest molecules. The study broadens the still very limited use of H2ATIBDC as a spacer and lead(II) ion for crystal engineering of MOFs with channels and cavities. These compounds represent the first examples of lead(II) complexes with H2ATIBDC.

The cosolvent-dependent assembly of a family of three blue fluorescent lead(II)-coordination polymers with 5-amino-2,4,6-tribromoisophthalic acid

By modulating the synthetic strategy based on changing the cosolvent in the synthesis, the aqueous medium assembly of lead(II) with H2ATBIP in the presence of different cosolvents, N,N-dimethylacetamide (DMA), methanol (CH3OH) or N,N-dimethylformamide (DMF), leads to a family of three lead(II) coordination polymers: [Pb(ATBIP)(H2O)2]·2H2O (1), [Pb(ATBIP)(H2O)(CH3OH)]·H2O (2) and [Pb(ATBIP)(H2O)(DMF)]·H2O (3) [H2ATBIP = 5-amino-2,4,6-tribromoisophthalic acid]. Complex 1 exhibits an interesting double chain structure with [Pb2(OH2)2] as the secondary building unit (SBU), which further assembles into a 3D supramolecular framework through the C–Br⋯Br halogen bonds and hydrogen bonds. Furthermore, the discrete water octamer (H2O)8 is found. The cosolvents, DMF and CH3OH, which simultaneously act as the coordinated small molecules, have significant influences on the formation of different crystalline architectures. Complex 2 features a 2D network constructed by the 21 helical carboxylate-bridged Pb(II) chains [Pb2(COO)2]n (SBUs) linked by the ligand ATBIP2−. The intralayer C–Br⋯Br halogen bond is found and a 3D supramolecular framework is formed by the interlayer hydrogen bonds. Complex 3 crystallizes in the chiral space group P41212 and possesses a 2D (4,4)-homochiral layer built from the centrosymmetrical SBU [Pb2(COO)2] bridged by the ligand ATBIP2−. The interlayer hydrogen bonds further extend the chiral layers in 3 into a 3D supramolecular homochiral framework. The coordination modes of the ligand ATBIP2− are greatly dependent on the cosolvents. Complex 3 loses crystallinity in the air and forms the material [Pb(ATBIP)(DMF)] (3A). Thermal stability and solid state fluorescent properties of 1, 2 and 3A have been studied. The second harmonic generation (SHG) property of 3A is also studied.

Synthesis and characterization of a pair of temperature and cosolvent-dependent Zn(II)-organic frameworks containing a novel discrete single-walled Zn(II)-organic coordination polymer nanotube

A pair of temperature and cosolvent-controlled assemblies of one dimensional (1-D) and two dimensional (2-D) Zn(II)-organic frameworks (ZOFs] based on 5-iodoisophthalic acid (H2IIP) and an auxiliary flexible ligand, 1,4-bis(triazol-1-ylmethyl)benzene (bbtz) with different structures, has been rationally designed and successfully synthesized. Results show that when the reaction was carried out under ambient condition, the novel discrete single-walled Zn(II)-organic coordination polymer nanotube {[Zn(IIP)(bbtz)(H2O)]·H2O}n (SWCPNT-1), which shows a fascinating 3-D supramolecular interdigitated columnar microporous architecture supported by face to face π⋯π stacking interactions and hydrogen bonds, was generated, whereas under solvothermal condition at 120 °C, an interesting 3-D-polycatenated array of layers, [Zn(IIP)(bbtz)] (2), which further extends into a threefold-interpenetrated 3-D supramolecular mesoporous framework with 1-D channels (ca. 3.46 × 1.54 nm2) through C–I⋯O halogen bonds would be obtained. Interestingly, the reversible in situ rapid rehydration from static air is significantly observed in the discrete SWCPNT-1, revealing its potential application as water absorbent and sensing material. The dehydrated SWCPNT-1 shows selective gas adsorption of CO2 over N2. Luminescent studies show that SWCPNT-1, dehydrated SWCPNT-1, and 2 exhibit blue fluorescence in the solid state. The water molecules in SWCPNT-1 affect its fluorescent property. Graphical Abstract The temperature and the cosolvent have great influence on the engineering of crystalline architectures of a pair of Zn(II)-organic frameworks with H2IIP and bbtz: the novel discrete single-walled Zn(II)-organic coordination polymer nanotube 1 and an interesting 3-D polycatenated array of layers 2. The dehydrated SWCPNT-1 exhibits reversible dehydration and rehydration from ambient air.

Preparation and characterization of two new metal–organic coordination polymers with 3,3′-azodibenzoic acid under N-donor auxiliary chelating ligand intervention

Reactions of 3,3′-azodibenzoic acid (H2azdc) with Mn(II) and Cd(II) in the presence of 1,10-phenanthroline (phen) yield two new metal–organic coordination polymers, {[Mn(azdc)(phen)(DMF)(H2O)]}n (1) and {[Cd(azdc)(phen)]}n (2), which display 1-D azdc-bridged coordination arrays with different topology. 1 was synthesized under ambient conditions and exhibits a zigzag chain structure, further extending into a 2-D supramolecular double layer through C–Hπ and C–HO hydrogen bonds. Solvothermally 2 was obtained and shows a double-chain structure. Adjacent double chains are linked by C–HN hydrogen bonds to give a 2-D supramolecular wavy double layer. Distinct extended 3-D supramolecular network architectures are further constructed with weak secondary interactions, especially aromatic stacking and hydrogen bonding as supramolecular driving forces. The coordination modes of azdc2− and crystalline architectures of the complexes depend on the central metal ions. The desolvation–resolvation behavior of 1 has been explored. Thermal stabilities of 1 and 2 have been studied. Solid-state fluorescence of 2 has been investigated.

catena-Poly[[(2,2′-bipyridine-κ2N,N′)cobalt(II)]-μ-oxalato-κ4O1,O2:O1′,O2′]

In the title compound, [Co(C2O4)(C10H8N2)]n, the oxalate group chelates two adjacent metal atoms, resulting in a zigzag chain running along the a axis. The CoII centre exists in an all cis-octahedral coordination geometry.

Diaqua­bis(1,10-phenanthroline-κ2N,N′)zinc(II) 2-hydr­oxy-5-sulfonatobenzoate tetra­hydrate

The water-coordinated metal centre in the title salt, [Zn(C12H8N2)2(H2O)2]C7H4O6S·4H2O, is chelated by the two bidentate N-heterocycles, leading to an overall distorted octahedral environment. The cation, dianion and solvent water molecules interact by O—H⋯O hydrogen bonds to form a layer motif. The SO3 group is disordered over two positions with respect to the O atoms in a 0.76 (1):0.24 (1) ratio. One of the solvent water molecules is also disordered over two positions in a 0.56 (4):0.44 (4) ratio.

Bis(4-amino­pyridinium) bis­(oxalato-κ2O,O′)cuprate(II) dihydrate

The CuII atom in the title salt, (C5H7N2)2[Cu(C2O4)2]·2H2O, is located on a center of inversion and is chelated by two oxalate groups in a square-planar coordination geometry. The cation, anion and water molecules interact through hydrogen bonds, forming a three-dimensional hydrogen-bonded network.

Positional isomeric and N-donor auxiliary chelating ligand effect on engineering crystalline architectures of four lead(II) complexes with diverse fluorescent properties

This work presents an investigation on the positions of the substituent and N-donor auxiliary chelating ligand (bipy/phen) effect on engineering of crystalline architectures of four Pb(II) complexes with a pair of methyl-substituted 3-sulfobenzoic isomers: [Pb(4-msba)(phen)(H2O)] (1), [Pb(4-msba)(bipy)(H2O)]·H2O (2), [Pb(5-msba)(phen)2]·9H2O (3), and [Pb2(5-msba)2(bipy)2(H2O)2] (4) (4/5-msba = 4/5-methyl-3-sulfobenzoate, phen = 1,10-phenanthroline and bipy = 2,2′-bipyridine). The lead(II) ions exhibit hemidirected geometry in 1–4. The positions of the methyl as well as the auxiliary chelating ligands influence coordination modes of the sulfonates and thus determine the architectures. As the position of methyl in aromatic ring changes from 4 to 5, the structures change from 2-D sheet-like compounds for 1 and 2 to 0-D dimeric species for 3 and 4. A water cluster (H2O)18 exists in 3, which further assembles into a water tape with a new pattern T4(3)4(3)10(3)A4. Complex 3 loses crystallinity rapidly in the open air and turns into [Pb(5-msba)(phen)2]·2H2O (3A). Thermal stabilities and solid state fluorescent properties of 1, 2, 3A, and 4 have been studied.

(5-Amino­isophthalato-κN)triaqua­(1,10-phenanthroline-κ2 N,N′)cobalt(II) trihydrate

The NiII atom in the title compound, [Ni(C8H5NO4)(C12H8N2)(H2O)3]·3H2O, is six-coordinated in an NiN3O3 octahedral geometry. The triply water-coordinated NiII atom is chelated by the phenantroline ligand and is additionally coordinated by the amino group of the 5-aminoisophtalate anion. The anion, the coordinated and the uncoordinated water molecules interact through an extensive O—H⋯O and N—H⋯O hydrogen-bonding network, generating a three-dimensional cage-like network.