Self-assembly Of Zn Research Articles

Construction and catalytic effects of solvent- and metal(ii)-dependent products: the process of transformation of 0D structures into 3D structures

The dimensions of M(ii) complexes are dependent on the solvents or metals(ii) employed, and a transformation of the cage into 3D occurs. Zn(ii) and Cu(ii) species are effective catalysts in transesterification and catechol oxidation, respectively.

Selective Conversions of CO2 into Value-Added Chemicals via Cooperative Catalysis Using Multifunctional Catalysts

Abstract Carbon dioxide (CO2) is not only a greenhouse gas but also a renewable carbon source for organic synthesis. Here we have summarized our studies on the conversions of CO2 into value-added chemicals via cooperative catalysis using multifunctional catalysts. For example, bifunctional metalloporphyrin catalysts with quaternary ammonium halides were developed for the selective synthesis of cyclic carbonates or polycarbonates from epoxides and CO2. Bifunctional MgII and ZnII porphyrins showed high catalytic activity for the synthesis of cyclic carbonates, while bifunctional AlIII porphyrins catalyzed the copolymerization of cyclohexene oxide and CO2 to give poly(cyclohexene carbonate). The high catalytic activities resulted from the cooperative action of the central metal ion and the quaternary ammonium salts. Chiral catalysts for the kinetic resolution of terminal or internal epoxides with CO2 were also developed. In addition, macrocyclic multinuclear metal complex Zn5L3, which was synthesized by the self-assembly of Zn(OAc)2 and a BINOL derivative (L), catalyzed the reduction of CO2 with phenylsilane to produce various useful synthetic intermediates and organic compounds.

A 8-fold interpenetrated metal-organic framework: Luminescent property and photocatalytic dye degradation performance

The self-assembly of Zn(NO3)2·6H2O, benzene-p-dicarboxylic acid (H2BDC) and tris(4-(4H-1,2,4-triazol-4-yl)phenyl)amine (L) affords a new Zn(II)-based metal-organic framework (MOF) with the formula of {[Zn3(L)(BDC)3(H2O)3]·3.5H2O}n (1). The structural determination results reveal that complex 1 demonstrates a 8-fold interpenetrated three-dimensional network with a 3-connected srs net. The photoluminescent study shows that the interligand-based charge-transfer contributes to the strong emission of 1 ​at room temperature. Furthermore, complex 1 could be applied as an efficient photocatalyst for the elimination of Rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) with the degradation efficiency all above 90% within 70 ​min under UV light irradiation. In connection to this, the detailed degradation mechanism has been probed both experimentally and computationally.

Two new Zinc (II)-viologen coordination polymers: Syntheses, structures, and photochromic behaviors

The self-assembly of Zn (II) ions with monosubstituted viologen ligand 1-(3-carboxybenzyl)-4,4’-bipyridinium chloride (m-Hbcbpy·Cl) and 1,3,5-benzenetricarboxylic acid (H3BTC) under solvothermal conditions results in two coordination polymers, namely, {[Zn(bcbpy)Cl2]·H2O}n(1) and {[Zn(bcbpy)(HBTC)H2O]·2H2O}n(2). Due to the formation of viologen radicals, the two compounds exhibit a triple photochromic behavior to sunlight, UV light and blue light through electron transfer, and the sequence of light response time is 1 > 2. Photochromic mechanisms and the relationships between structures and properties have been discussed adequately. And using time-dependent density functional theory (TDDFT) to study the discoloration mechanism of compounds 1 and 2. More importantly, compound 1 can be deposited on filter paper and displays potential applications as an inkless printing material. In addition, the capabilities of compound 2 to act as anti-counterfeiting materials for QR codes have also been investigated.

Subtle Ligand Spacer Change in 2D Metal-Organic Framework Sheets for Dual Turn-On/Turn-Off Sensing of Acetylacetone and Turn-On Sensing of Water in Organic Solvents.

Metal-organic framework (MOF)-based sensors for the detection of various analyte molecules has been a subject of absolute importance. However, most of these sensors rely on the turn-off (quenching) transduction response, while those reporting turn-on response are very rare. In this article, we have synthesized two new MOF-based sensors, {[Zn2(oxdz)2(tpbn)]·14H2O}n (1) and {[Zn2(oxdz)2(tpxn)]·10H2O·2C2H5OH}n (2), via the self-assembly of Zn(II) metal ions, a fluorogenic oxdz2- linker, and bis(tridentate) ligands (tpbn and tpxn) under ambient conditions. Their formation from such a self-assembly process has been evaluated on the basis of the geometry around the five-coordinated Zn(II), preferential meridional binding of the bis(tridentate) ligands, and diverse binding of the carboxylate groups in oxdz2-. Although 1 and 2 are isostructural, a difference in the transduction mechanism for the sensing of acetylacetone in organic solvents (turn-on for 1 and turn-off for 2) is observed and can be attributed to the spacer in the bis(tridentate) ligands. We have demonstrated the competing effect of the nonradiative interactions and photoinduced electron transfer toward the sensing mechanism. The results are well-supported by the Fourier transform infrared spectroscopy study, intensity versus concentration plots, spectral overlap measurements, time-resolved fluorescence studies, and MM2 and density functional theory calculations. Furthermore, we have showcased the utilization of 1 for the sensing of trace amounts of water in organic solvents.

Pair of chiral molecular ladders and successive hydration in single-crystal-to-single-crystal mode

Self-assembly of Zn(NO3)2 with a pair of new tridentate chiral Ls produced a pair of chiral ladder-type 1D coordination polymers, where crystals were transformed into different hydrated products of zigzag 1Ds depending on chirality in the SCSC mode.

Two new diverse 3D MOFs induced by ligand salt type: Photocatalytic performance

Self-assembly of Zn(Ac)2·2H2O with π-conjugated and rigid multicarboxylate ligand 1,3,5-benzenetricarboxylic acid (H3BTC) and flexible N-donor linker 1,3-bis(2-methylimidazolyl)propane generated two new metal-organic frameworks (MOFs), [Zn7 (μ3-OH)2(BTC)4 (bmp)2(H2O)4·2H2O·2DMF]n (1) and [Zn(BTC) (Hbmp)·H2O]n (2). 1 has a pentanuclear [Zn5 (μ3-OH)2] subunit, which is further connected by the BTC ligands to shape a layer. The 2D layer is further bridged by BTC and monuclear metal to form a 3D framework. The 3D zinc-BTC substructure has 1D open channels filled by bmp ligands. Polymer 2 shows a 4-connected 3D cds network. While a variation of bmp was imported into the zinc-btc system yielding a two different topological networks, demonstrating that the ligand salt type has an apparent effect in the building of the final networks. Their photochemical properties were measured.

Two new coordination polymers constructed by two viologen-derived ligands: Structure and photochromism

Two new 1D Zn(II) and Mn(II) coordination polymers, namely, [ZnL1(H2O)Cl]·[(Cl)·2H2O] (CP-1), [Mn(L2)2(N3)2]·3H2O (CP-2) ([H2L1]Cl2 = [1,1′-bis(3-carboxylatobenzyl)-4,4′-bipyridinium] dichloride and [H2L2]Cl2 = [1,1′-bis(4-carboxylatobenzyl)-4,4′-bipyridinium] dichloride) have been synthesized successfully by the self-assembly of Zn(II) and Mn(II), N3ˉ and two different viologen ligands, respectively. CP-1 shows a zigzag chain structure which the Zn(II) ions are linked by L1 ligands, while CP-2 shows a wavy chain structure which the Mn(II) ions are linked by L2 ligands. Both of them showed typical electrochemical redox properties and photochromic properties, which involved the radicals formation via photoinduced electron transfer. The mechanism of photochromism of two compounds has been demonstrated by UV–vis absorption characterization analysis, electron paramagnetic resonance spectroscopy (EPR), X-ray photoelectron spectra (XPS) and structural analysis.

Syntheses, Crystal Structures, Luminescent Properties, and Electrochemical Synthesis of Group 12 Element Coordination Polymers with 4-Substituted 1,2,4-Triazole Ligands

The self-assembly of Zn(II), Cd(II), or Hg(II) salts with long flexible 1,2,4-triazole-based ligands resulted in coordination polymers and mononuclear complexes of diverse topology. Indeed, the 1D chain [ZnCl2(btpm)] (1) (P1), the 2D square grid [Zn(btpm)2(H2O)](BF4)2·2btpm·8H2O (2) (P21212), and the 1D chain [Cd3Cl6(btpm)2]·8H2O (3) (P1) with btpm = bis(4-(1,2,4-triazol-4-yl)phenyl)methane were crystallized. In addition, the mononuclear complexes [ZnCl2(ppt)2] (4) (I2) and [HgBr2(ppt)2] (5) (C2) were obtained along with the 1D polymer [Cd2Cl2(ppt)4](CdCl4)·4DMF (6) (P1) with ppt = (4-phenoxyphenyl)-1,2,4-triazole. 1D chains of the formula [ZnCl2(tpca)] (7) (P21/c) and [HgBr2(tpca)] (8) (P21/c) along with the 2D net [Cd(tpca)2(H2O)2]·2H2O (C2/c) (9) with tpca = N-(1,2,4-triazol-4-yl)pyridine-3-carboxamide were obtained. In addition, the X-ray structures of tpca and ppt are described. All compounds display solid-state blue luminescence, which has been investigated in detail. Electrochemical synthesis of ...

Design of a Primary-Amide-Functionalized Highly Efficient and Recyclable Hydrogen-Bond-Donating Heterogeneous Catalyst for the Friedel–Crafts Alkylation of Indoles with β-Nitrostyrenes

A primary-amide-functionalized metal organic framework, {[Zn2(2-BQBG)(BDC)2]·10H2O}n (1) (in which 2-BQBG = 2,2′-(butane-1,4-diylbis((quinolin-2-ylmethyl)azanediyl))diacetamide and BDC = 1,4-benzenedicarboxylate), has been found to be a highly efficient hydrogen-bond-donating (HBD) heterogeneous catalyst for the Friedel–Crafts alkylation of indole with β-nitrostyrenes under mild reaction conditions (catalyst loading: 3 mol %; reaction conditions: 12 h and 35 °C). The catalyst can be easily separated from the reaction mixture by simple filtration for its reuse in four consecutive cycles with very little loss of activity. More importantly, the one-pot room temperature synthesis of 1 from the self-assembly of Zn(OAc)2·2H2O and 2-BQBG (in CH3OH) and Na2BDC (in H2O) can be easily scaled-up for obtaining multigram quantities in few hours. In order to showcase its versatility, the substrate scope included a variety of substituted indoles and different β-nitrostyrene derivatives forming the desired products in good to high yields. For its catalytic action, a direct proof for the key step in the proposed mechanism, based on the interaction of a primary-amide group in the 2-BQBG ligand with the nitro group of β-nitrostyrene through hydrogen bonding, is provided from the enhancement in fluorescence intensity of 1 upon successive addition of β-nitrostyrene.

Synthesis, crystal structure and photoluminescence of a three-dimensional zinc coordination compound with NBO-type topology.

The assembly of metal-organic frameworks (MOFs) with metal ions and organic ligands is currently attracting considerable attention in crystal engineering and materials science due to their intriguing architectures and potential applications. A new three-dimensional MOF, namely poly[[diaqua(μ8-para-terphenyl-3,3',5,5'-tetracarboxylato)dizinc(II)] dimethylformamide disolvate monohydrate], {[Zn2(C22H10O8)(H2O)2]·2C3H7NO·H2O}n, was synthesized by the self-assembly of Zn(NO3)2·6H2O and para-terphenyl-3,3',5,5'-tetracarboxylic acid (H4TPTC) under solvothermal conditions. The compound was structurally characterized by FT-IR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. Each ZnII ion is located in a square-pyramidal geometry and is coordinated by four carboxylate O atoms from four different TPTC4- ligands. Pairs of adjacent equivalent ZnII ions are bridged by four carboxylate groups, forming [Zn2(O2CR)4] (R = terphenyl) paddle-wheel units. One aqua ligand binds to each ZnII centre along the paddle-wheel axis. Each [Zn2(O2CR)4] paddle wheel is further linked to four terphenyl connectors to give a three-dimensional framework with NBO-type topology. The thermal stability and solid-state photoluminescence properties of the title compound have also been investigated.

A three-dimensional ZnII coordination network based on 5,5'-methylenebis(2,4,6-trimethylisophthalic acid) and 2,7-bis(1H-imidazol-1-yl)fluorene: synthesis, structure and luminescence properties.

In recent years, coordination polymers constructed from multidentate carboxylate ligands and N-containing ligands have attracted much attention since these ligands can adopt a rich variety of coordination modes which can lead to crystalline products with intriguing structures and interesting properties. A new coordination polymer, namely poly[[diaqua[μ-2,7-bis(1H-imidazol-1-yl)fluorene-κ2N3:N3'][μ-5,5'-methylenebis(3-carboxy-2,4,6-trimethylbenzoato)-κ2O1:O1']zinc(II)] hemihydrate], {[Zn(C23H22O8)(C19H14N4)(H2O)2]·0.5H2O}n, 1, was prepared by the self-assembly of Zn(NO3)2·6H2O with 5,5'-methylenebis(2,4,6-trimethylisophthalic acid) (H4BTMIPA) and 2,7-bis(1H-imidazol-1-yl)fluorene (BIF) under solvothermal conditions. The structure of 1 was determined by elemental analysis, single-crystal X-ray crystallography, powder X-ray diffraction, IR spectroscopy and thermogravimetric analysis. Each ZnII ion is six-coordinated by two O atoms from two H2BTMIPA2- ligands, by two N atoms from two BIF ligands and by two water molecules, forming a distorted octahedral ZnN2O4 coordination geometry. Adjacent ZnII ions are linked by H2BTMIPA2- ligands and BIF ligands, leading to the formation of a two-dimensional (2D) (4,4)-sql network, and intermolecular hydrogen-bonding interactions connect the 2D layer structure into the three-dimensional (3D) supramolecular structure. Each 2D layer contains two kinds of helices with the same direction, which are opposite in adjacent layers. The luminescence properties of complex 1 in the solid state have also been investigated.

Construction and photoluminescence properties of a three-dimensional ZnII coordination network based on naphthalene-1,4-dicarboxylic acid and 1,6-bis(pyridin-3-yl)-1,3,5-hexatriene.

In recent years, coordination polymers constructed from multidentate carboxylate and pyridyl ligands have attracted much attention because these ligands can adopt a rich variety of coordination modes and thus lead to the formation of crystalline products with intriguing structures and interesting properties. A new coordination polymer, namely poly[[μ2-1,6-bis(pyridin-3-yl)-1,3,5-hexatriene-κ2N:N'](μ3-naphthalene-1,4-dicarboxylato-κ4O1,O1':O4:O4')zinc(II)], [Zn(C12H6O4)(C16H14N2)]n, has been prepared by the self-assembly of Zn(NO3)2·6H2O, naphthalene-1,4-dicarboxylic acid (1,4-H2ndc) and 1,6-bis(pyridin-3-yl)-1,3,5-hexatriene (3,3'-bphte) under hydrothermal conditions. The title compound has been structurally characterized by IR spectroscopy, elemental analysis, powder X-ray diffraction and single-crystal X-ray diffraction analysis. Each ZnII ion is six-coordinated by four O atoms from three 1,4-ndc2- ligands and by two N atoms from two 3,3'-bphte ligands, forming a distorted octahedral ZnO4N2 coordination geometry. Pairs of ZnII ions are linked by 1,4-ndc2- ligands, leading to the formation of a two-dimensional square lattice (sql) layer extending in the ab plane. In the crystal, adjacent layers are further connected by 3,3'-bphte bridges, generating a three-dimensional architecture. From a topological viewpoint, if each dinuclear zinc unit is considered as a 6-connected node and the 1,4-ndc2- and 3,3'-bphte ligands are regarded as linkers, the structure can be simplified as a unique three-dimensional 6-connected framework with the point symbol 446108. The thermal stability and solid-state photoluminescence properties have also been investigated.

Synthesis and single crystal X-ray diffraction studies of coumarin-based Zn(II) and Mn(II) complexes, involving supramolecular interactions

In this work we describe the synthesis and characterization of two supramolecular coordination complexes, namely [Zn(Cuma)2(MeOH)2] 2 and [Mn(Cuma)2(MeOH)2] 3, obtained from the self-assembly of Zn(II) and Mn(II) acceptors with the 3-benzoyl-4-hydroxycoumarin ligand donor (1) possessing the β,β′-diketonate moiety. The coordination mode of the ligand, incorporating intra- and intermolecular hydrogen bonds with the metal atoms, was established by single crystal X-ray diffraction. The Zn(II) and Mn(II) complexes each show a 1D structural motif which is further assembled into 3D supramolecular architecture by hydrogen bonds and π-stacking interactions.

A sandwich-shaped M3L2 zinc(ii) complex containing 1,3,5-tris(dimethyl(pyridin-3-yl)silyl)benzene: selective photoluminescence recognition of diiodomethane.

Self-assembly of Zn(ClO4)2 with 1,3,5-tris(dimethyl(pyridin-3-yl)silyl)benzene (L) as a new C3-symmetric tridentate N-donor gives rise to a discrete sandwich-shaped M3L2 architecture, [Zn3(μ-OH)3L2](ClO4)3·4CH3CN·2H2O. Its blue photoluminescence is significantly quenched only by CH2I2 among the various small molecules, CH2Cl2, CH2Br2, CHCl3, 1,2-dichloroethane, EtOH, CH3CN, benzene, toluene, and phenol.

Synthesis, crystal structure, and luminescent property of a discrete Zn3L3 metallomacrocycle constructed from 5-hydroxyisophthalic acid

An interesting discrete metallomacrocycle (MMC), [Zn3(L)3(H2O)6] · H2O (I), has been prepared by means of self-assembly of Zn(II) salt, 5-hydroxyisophthalic acid (H2L) as organic linker and 5,5’-(pyridine-2,6-diyl)diisophthalic acid (H4L’) as structure-directing agentunder hydrothermal condition. In complex I, the planar trinuclearmetal-organic macrocycles are arranged into 2D sheet layers connected by strong hydrogen bonded between OH groups of the ligands. Then they stack into 3D supramolecular architecture in–ABAB–array way to give a small 1D open channel along the c axis (CIF file CCDC no. 1053024). Additionally, thermal stability and luminescence properties of I were also investigated.

A New 3D Pillar-Layered Zn(II) Coordination Polymer Constructed From the Mixed Flexible Polycarboxylate and Bis(pyridyl)-Based Ligands

A new Zn(II) coordination polymer, namely [Zn3(TTHA)(bpp)(H2O)3]n·4n(H2O) (1 H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, bpp = 1,3-di(4-pyridyl)propane), has been synthesized by the hydrothermal self-assembly of Zn(NO3)2·6H2O, H6TTHA and bpp. Single-crystal x-ray diffraction analysis reveals that compound 1 features a 3D framework, which can be described as the 2D layers constructed by the Zn(II) ions and TTHA6– ligands pillared by the bpp ligands. Furthermore, the thermal stability and luminescent property of compound 1 were investigated.

Organization and Energy Transfer of Fused Aromatic Hydrocarbon Guests within Anion-Confining Nanochannel MOFs.

The self-assembly of Zn(II) ions with 1,3,5-tris(isonicotinoyloxyethyl)cyanurate produces new topological (4(2)⋅12(4))3(4(3))4 2D metal-organic frameworks (MOFs) with anion-confining cages. The eclipsed assembly of each 2D MOF by π-π stacking of cyanurate moieties (3.352(5) Å) forms 3D MOFs consisting of nanochannels (10.5 Å). Two of the three anions are confined in each peanut-type cage, resulting in hydrophobicity of the nanochannels. The hydrophobic nanochannel effectively adsorbs a wide range of fused aromatic hydrocarbons (FAHs) as monomers or dimers, rendering it potentially highly useful as an energy-transfer material.

A novel trimeric Zn (II) complex based on 8-hydroxyquinoline with trifluoromethylbenzene group: Synthesis, crystal structure, photophysical properties and DNA binding

A novel 2-substituted-8-hydroxyquinoline ligand (E)-2-[2-(4-trifluoromethylphenyl)ethenyl]-8-hydroxyquinoline (3, HL) was synthesized and characterized by ESI-MS, NMR spectroscopy and elemental analysis. Using solvothermal method, a trimeric complex [Zn3L6] (4) was fabricated by self-assembly of Zn(II) ions with 3. X-ray structural analysis shows that 4 exhibits a trinuclear core, which was bridged and encapsulated by six 8-hydroxyquinolinate-based ligands. The supramolecular structure of 4 features a lamellar solid constructed by aromatic stacking interactions and nonclassical C–H···F hydrogen bonds derived from 4-trifluoromethylphenyl group of the 3. The coordination behavior of zinc salt and 3 in solution was performed by 1H NMR, UV–vis and Photoluminescence (PL). The experimental results show that the complex 4 emits yellow luminescence in the solid state. To investigate its properties further, we also studied the thermal stability, photophysical properties (fluorescent emission, lifetime) of complex 4, and the interactions between 4 and C60 or EtBr–DNA system.

Two nanosized 3d-4f clusters featuring four Ln6 octahedra encapsulating a Zn4 tetrahedron.

Two high-nuclearity 3d-4f clusters Ln24Zn4 (Ln = Gd and Sm) featuring four Ln6 octahedra encapsulating a Zn4 tetrahedron were obtained through the self-assembly of Zn(OAc)2 and Ln(ClO4)3. Quantum Monte Carlo (QMC) simulations show the antiferromagnetic coupling between Gd(3+) ions. Studies of the magnetocaloric effect (MCE) show that the Gd24Zn4 cluster exhibits the entropy change (-ΔSm) of 31.4 J kg(-1) K(-1).