Polycatenated Framework Research Articles

Multidirectional Solvent-Induced Structural Transformation in Designing a Series of Polycatenated Cobalt(II) Coordination Polymers: Impact on Carbon Dioxide and Hydrogen Uptake.

Coordination polymers with external stimuli-responsive structural transformation acquired paramount importance in the advanced material research field due to their eye-catching application to deal with the existing challenging issue, and Co(II) metal complex with d7 electronic configuration is a renowned candidate for kinetic accountability and has the potentiality of structural transformation. Bearing these factors in mind, here, a Co(II) congener of a previously reported high hydrogen-adsorbing Cu(II)-based coordination polymer (CP), {[Cu(4-bpe)(2-ntp)]}n [where 2-ntp2- = 2-nitroterephthalate and 4-bpe = 1,2-bis-(4-pyridyl)ethane], has been synthesized to study the metal change impact on hydrogen adsorption and solvent-induced structural transformation with their impact on hydrogen uptake. This modified framework has a 2D + 2D → 3D inclined polycatenated framework as comparable to our previously published Cu(II) framework. Here, on the variation of different solvents, the labile Co(II)-containing framework exhibits a structural change through single-crystal to single-crystal (SC-SC) structural transformation and results in three new framework structures. All four frameworks are structurally characterized by elemental analysis, IR, PXRD, TGA, and single-crystal X-ray diffraction. The desolvated parent framework with exposed metal centers exhibits excellent results of H2 adsorption of 1.3 wt % (145 cc/g) at 77 K and pressure of 1 bar with structural sustainability and CO2 uptake of 130 cc/g at 195 K and 1 bar. For the other three solvent-mediated structural derivatives, H2 and CO2 adsorption have been studied, and the results are correlated with their structure.

Solvent induced reversible single-crystal-to-single-crystal structural transformation in dynamic metal organic frameworks: a case of enhanced hydrogen sorption in polycatenated framework

Two MOFs are showing a low-energy solid-state transformation and a dissolution–recrystallization structural transformation respectively. The hydrogen uptake was found to be influenced by the polycatenation present in one of the frameworks.

Experimental and theoretical investigation on the hydrochromic property of a Ni(II)-containing coordination polymer with an inclined 2D → 3D polycatenation architecture

In recent years, hydrochromic materials have been widely used for visual inspection, rewriting papers, humidity sensors, and the paint and coating industry. However, the investigation on hydrochromic coordination polymers is relatively rare. In this work, a hydrochromic coordination polymer [Ni(L1)(L2)(H2O)(DMF)]·DMF (1) (L1 = N,N'-di(4-pyridyl)-1,4,5,8-naphthalene diimide, H2L2 = 4,4′-stilbenedicarboxylic acid, and DMF = N,N'-dimethylformamide) is synthesized by employing the π-electron-deficient L1 as the main ligand under the solvothermal condition. Compound 1 displays a rare inclined 2D → 3D polycatenation framework, resulting in extraordinary flexibility and stability that enables compound 1 to undergo cell compression or expansion after water loss or absorption, thereby altering the distance between the electron donor and the acceptor, causing the generation or quenching of radicals and hydrochromic phenomenon. Compound 1 undergoes a color change from yellow to green upon heating at 150 °C within five minutes or placing in a desiccator with concentrated sulfuric acid as desiccant for several hours. The green samples can be restored to yellow after being placed in the air for about two minutes. If the green samples contact with water directly, they can immediately return to yellow. The hydrochromic mechanism is investigated by thermogravimetric analysis, UV–Vis, infrared spectra, electron paramagnetic resonance spectra, powder X-ray diffraction spectra and density functional theory simulation.

A new polycatenated framework encapsulated Keggin-type silicotungstate crystalline compound with bifunctional electrochemical performances

A new polycatenated framework encapsulated Keggin-type silicotungstate crystalline compound, L0.5[Cu2L3.5(SiW12O40)] (1) (L = 1,4-bis(1-imidazol-yl)-2,5-dimethyl benzene), has been prepared by solvothermal conditions. A new 3D polycatenaned framework was obtained by the 1D track chains and 2D grid layers catenating with each other, and the Keggin-type POMs are encapsulated in host framework. Compound 1 shows a rare case of 3D polycatenated framework encapsulated Keggin-type polyoxometalate. The electrocatalytic efficiency is ca. 179.2% containing 10 mM NO2−. Meanwhile, 1-GCE shows higher specific capacitance of 159.2 F g−1 (3 A g−1) than the majority of the reported POM-based crystalline compounds.

Three new entangled Zn(II)/Cd(II)-MOFs based on a triangular tri(4- imidazolylphenyl)amine and different carboxylic acid : Crystal structures, and luminescent properties

Three new entangled metal-organic frameworks, namely [Cd(TIPA)(HCOO)2]·4H2O (1), [Cd2Cl2(TIPA)2(NDC)2]·4H2O (2) and [Zn2(TIPA)(HCOO) (NDC)1.5]·DMF·CH3OH·2H2O (3) (TIPA = tri(4-imidazolylphenyl)amine, H2NDC = naphthalene-2,6- dicarboxylic acid, DMF = N,N’-dimethylformamide), have been obtained under solvothermal conditions. 1 shows a 2-D → 3-D parallel/parallel inclined polycatenated framework. 2 represents a 3-D polythreaded supramolecular architecture consisting of (3,4,6)-connected 2-D sheets with a (4·52)2(42·510·6·72)(54·6·8)2 topology. 3 has a (3,6)-connected 3-D 2-fold interpenetrating network with a Schläfli symbol of (42·6)(44·610·8). The luminescent properties of the complexes 1, 2 and 3 in the solid state have also been investigated at room temperature and 77 K respectively.

A novel polyoxometalate-encapsulating 3D polycatenated metal-organic framework

A novel polyoxometalate-encapsulating polycatenated metal-organic framework, (bib)0.5[Cu2(bib)3.5(GeW12O40)]·H2O (1) (bib = 1,4-bis(1-imidazol-yl)-2,5-dimethyl benzene), has been synthesized under hydrothermal conditions. In compound 1, 1D molecular ladders and 2D square grid layers is further catenated to the two adjacent such motifs in inclined fashion to give an 1D+2D→3D polycatenaned metal-organic framework with nanotube channels, in which nanosized Keggin anions as guests are encapsulated for the first time. Compound 1 represents a first case of Keggin-type polyoxometalate-encapsulating 1D+2D→3D polycatenated metal-organic framework. The electrochemical studies show that modified electrode of 1 exhibits highly efficient electrocatalytic activity toward reduction of inorganic molecule bromate (BrO3-). The electrocatalytic reaction mechanism of 1-GCE toward reduction of BrO3- has been illuminated. The photoluminescence property of 1 was also investigated.

Three novel polyoxometalate-based inorganic-organic hybrid materials based on 2,6-bis(1,2,4-triazol-1-yl)pyridine.

Three novel inorganic–organic hybrid materials [Co(btp)2(W5O16)(H2O)]n (1), [Cd3(btp)6(PW12O40)2(H2O)6·6H2O]n (2), and [Ag3(btp)2(PMo12O40)·1.5H2O]n (3) (btp = 2,6-bis(1,2,4-triazol-1-yl)pyridine) have been hydrothermally synthesized and characterized by IR spectroscopy, single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), elemental analysis and thermal gravimetric analysis (TGA). The most striking structure feature of compound 1 is a 3D polycatenation framework, interpenetrated by a 2D 4-connected sql topology layer and a 3D 6-connected rob topology framework. Compound 2 exhibits a rare meso-helices 3D network with different chiralities crossing coexistence. Compound 3 also holds a 3D framework formed by linking terminal oxygen atoms of [α-PMo12O40]3− anions and silver ions in a 2D metal–organic layer. Compound 1 displays antiferromagnetic behavior. The luminescence, electrochemical and photocatalytic properties of compounds 1–3 have also been investigated. Compound 3 exhibits significant electrochemical activity for the reduction of H2O2 while compounds 1 and 2 show efficient photocatalytic activities for the degradation of Rhodamine B (RhB). Furthermore, the three compounds display luminescence behaviors in the solid state.

Designed Cluster Assembly of Multidimensional Titanium Coordination Polymers: Syntheses, Crystal Structure and Properties.

The exploitation of new titanium-based coordination polymers (Ti CPs) with high crystallinity is difficult but highly desirable for their potential applications in photocatalysis. Herein, a cluster-cooperative assemble strategy is developed to synthesize Ti CPs. By utilizing various bifunctional ligands containing carboxylate acids and N-donor groups, we successfully assembled the zero-dimensional (0D) [(Ti3 O)(iPrO)8 ]2+ or [(Ti4 O2 )(iPrO)6 ]6+ clusters into one-dimensional (1D) tube-, ribbon-, or helical chain-shape architectures, two-dimensional (2D) layered structures, and a rare parallel 2D→three-dimensional (3D) polycatenation framework with various copper iodide dopants, including rhombus- or wing-shaped Cu2 I2 and tetrahedron- or ladder-shaped Cu4 I4 . The as-synthesized compounds display strong absorption in the visible region with narrow band gaps ranging from 1.70 to 2.72 eV and exhibit good photocatalytic activities in the degradation of organic pollutants.

A microporous metal-organic framework with unusual 2D → 3D polycatenation for selective sorption of CO2 over CH4 at room temperature

By appealing to the pillared-layer strategy, a new Zn(II)-based microporous polycatenated metal-organic framework {[Zn2(bpydb)2(EtOH)(4-bpdb)](DMF)4(EtOH)2}n (1, bpydb = 4,4′-(4,4′-bipyridine-2,6-diyl)dibenzoate, 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, DMF = N,N-dimethylformamide) with Lewis basic sites on the pore surface has been designed and generated by the solvothermal reaction of mixed ligands (bpydbH2 and 4-bpdb) and Zn(NO3)2 · 6H2O. The structure of 1 displays a 3D pillared-bilayer network generated from polycatenation of the 2D bilayers with an accessible solvent void of 43%. Its porosity has been verified by the N2 sorption at 77 K, which reveals a BET surface of 545 m2/g and pore volume of 0.324 cm3/g. Moreover, compound 1 shows excellent adsorption selectivity for CO2 over CH4 around room temperature, which has been correlated to the specific interaction of CO2 with functional azine groups that decorated the pore channels.

Exploring New Assembly Modes of Uranyl Terephthalate: Templated Syntheses and Structural Regulation of a Series of Rare 2D → 3D Polycatenated Frameworks.

The reaction of uranyl nitrate with terephthalic acid (H2TP) under hydrothermal conditions in the presence of an organic base, 1,3-(4,4'-bispyridyl)propane (BPP) or 4,4'-bipyridine (BPY), provided four uranyl terephthalate compounds with different entangled structures by a pH-tuning method. [UO2(TP)1.5](H2BPP)0.5·2H2O (1) obtained in a relatively acidic solution (final aqueous pH, 4.28) crystallizes in the form of a noninterpenetrated honeycomb-like two-dimensional network structure. An elevation of the solution pH (final pH, 5.21) promotes the formation of a dimeric uranyl-mediated polycatenated framework, [(UO2)2(μ-OH)2(TP)2]2(H2BPP)2·4.5H2O (2). Another new polycatenated framework with a monomeric uranyl unit, [(UO2)2(TP)3](H2BPP) (3), begins to emerge as a minor accompanying product of 2 when the pH is increased up to 6.61, and turns out to be a significant product at pH 7.00. When more rigid but small-size BPY molecules replace BPP molecules, [UO2(TP)1.5](H2BPP)0.5 (4) with a polycatenated framework similar to 3 was obtained in a relatively acidic solution (final pH, 4.81). The successful preparation of 2-4 represents the first report of uranyl-organic polycatenated frameworks derived from a simple H2TP linker. A direct comparison between these polycatenated frameworks and previously reported uranyl terephthalate compounds suggests that the template and cavity-filling effects of organic bases (such as BPP or BPY), in combination with specific hydrothermal conditions, promote the formation of uranyl terephthalate polycatenated frameworks.

Polycatenation tuned microporosity of two metal–tris(4′-carboxybiphenyl)amine frameworks with multilayer structures

By employing a nanosized tris(4'-carboxybiphenyl)amine ligand to assemble with Zn2+ ions, a novel trilayer network (FIR-37) and an unprecedented 2D → 3D microporous polycatenation framework (FIR-38) based on unusual tetralayers have been synthesized and structurally characterized. FIR-38 shows permanent porosity with a Langmuir surface area of 1408.4 m2 g-1.

Hydrogen Uptake by an Inclined Polycatenated Dynamic Metal-Organic Framework Based Material.

A 2D + 2D → 3D inclined polycatenated dynamic metal-organic framework of {[Cu(4-bpe)(2-ntp)(H2O)2]·2H2O}n [1, where 2-ntp2- = 2-nitroterephthalate and 4-bpe = 1,2-bis-(4-pyridyl)ethane] has been synthesized and characterized. The variable-temperature powder X-ray diffraction study indicates the dynamic nature of the inclined polycatenated framework, and the dehydrated framework with exposed metal centers exhibits excellent type I H2 adsorption of 1.94 wt % at 77 K and 1 bar of pressure.

Three unique MOFs constructed by 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene and dicarboxylates: From rhombic tetrameric zinc(II) 2D layer to 2D + 2D → 3D polycatenated frameworks

Three metal–organic networks, namely, [Zn2(Hnip)(4-bpdb)(nip)2(μ3-OH)] (1), {[Zn(tbip)(4-bpdb)1.5]·CH3OH}n (2), and {[Ni(1,3-bdc)(4-bpdb)]·2H2O}n (3) (4-bpdb=1.4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, H2nip=5-nitroisophthalic acid, H2tbip=5-tert-butylisophthalic acid, and 1,3-H2bdc=1,3-benzenedicarboxylic acid) are synthesized under hydrothermal conditions. The structure of 1 is built around uncommon rhombic {Zn4} clusters with double Td and double Oh Zn(II) geometries, which extend into a 2D network by the rigid deprotonated H2nip and 4-bpdb bridges. Meanwhile, 2 presents a novel 2D→3D parallel polycatenated framework assembled from 2D bilayers with cuboids as the fundamental building units. Compound 3 features an interesting 2D→3D inclined polycatenated network based on 44-sql subunits. Moreover, the thermal stabilities, photoluminescence, and magnetic properties of the compounds are also discussed.

The factors affecting the assembly of Keggin–metal–bimb systems: charge/polarity of Keggin polyanions and coordination modes of metal cations

To explore the influence of the charge/polarity of Keggin polyanions and coordination modes of transition metal cations on the construction of polyoxometalate (POM)-based hybrid compounds, we design two synthetic routes and obtain six new POM-based inorganic–organic hybrid compounds, namely, [Co5(H2O)6(bimb)8(PWVI10WV2O40)2]·14H2O (1), [Co2(bimb)2(GeW12O40)][bimb]·2H2O (2), [Co2(bimb)2(BW12O40)][Hbimb]·2H2O (3), [Co2(bimb)2(H2W12O40)][H2bimb]·2H2O (4), [Cu(bimb)(BW12O40)][H2bimb]2·2H2O (5) and [Ag2(bimb)2(BW12O40)][H3bimb]·2H2O (6) (bimb = 1,4-bis(1-imidazolyl)benzene). All compounds were characterized by elemental analyses, IR spectroscopy, powder X-ray diffraction and single-crystal X-ray diffraction. Compound 1 represents the first POM-based three-dimensional (3D) self-penetrating structure composed of a unique metal–organic polycatenated framework and tridentate Keggin clusters. Compounds 2, 3, 4 and 6 are isostructural, which show POMOF structures consisting of Keggin cluster guests and a metal–organic nanotube host. The structure of compound 5 is a simple 2D grid layer. The isolation of the title compounds is very informative for systematically understanding the effect of the charge/polarity of POMs and coordination modes of transition metal cations on the structures of POM-based hybrids. The effect of the charge/polarity of POMs and coordination modes of transition metal cations is discussed in this work. Additionally, the luminescence and electrochemical properties of 1–6 have been investigated in detail.

Umbellate Distortions of the Uranyl Coordination Environment Result in a Stable and Porous Polycatenated Framework That Can Effectively Remove Cesium from Aqueous Solutions

Searching for new chemically durable and radiation-resistant absorbent materials for actinides and their fission products generated in the nuclear fuel cycle remain highly desirable, for both waste management and contamination remediation. Here we present a rare case of 3D uranyl organic framework material built through polycatenating of three sets of graphene-like layers, which exhibits significant umbellate distortions in the uranyl equatorial planes studied thoroughly by linear transit calculations. This unique structural arrangement leads to high β and γ radiation-resistance and chemical stability in aqueous solutions within a wide pH range from 3 to 12. Being equipped with the highest surface area among all actinide compounds known to date and completely exchangeable [(CH3)2NH2](+) cations in the structure, this material is able to selectively remove cesium from aqueous solutions while retaining the polycatenated framework structure.

High surface area and Z' in a thermally stable 8-fold polycatenated hydrogen-bonded framework.

1,3,5-Tris(4-carboxyphenyl)benzene assembles into an intricate 8-fold polycatenated assembly of (6,3) hexagonal nets formed through hydrogen bonds and π-stacking. One polymorph features 56 independent molecules in the asymmetric unit, the largest Z' reported to date. The framework is permanently porous, with a BET surface area of 1095 m(2) g(-1) and readily adsorbs N2, H2 and CO2.

Two novel Ni(II) complexes with polycatenated networks: Structures and magnetic properties

Two nickel coordination polymers formulated as [Ni2(bpe)3(nip)2]n (1) and {[Ni(bpmp)(nip)(H2O)]·3H2O}n (2) (where H2nip=5-nitroisophthalic acid, bpe=1,2-bis-(4-pyridyl) ethane and bpmp=N,N′-bis-(4-pyridyl-methyl) piperazine) have been synthesized under hydrothermal condition. Single crystal X-ray diffraction analyses reveal that complex 1 presents a novel three-dimensional (3D) parallel polycatenated framework assembled from two-dimensional bilayers with cuboids as the fundamental building units. Compound 2 shows unusual 2D→3D inclined polycatenated framework consisting of two sets of equivalent 2D sql layers. The compounds have also been characterized by infrared spectra, elemental analysis, thermogravimetric analysis and powder X-ray diffraction. Magnetic studies reveal that these two compounds show similar antiferromagnetic interaction between Ni(II) ions.

Structural and functional studies on coordination polymers based on 5-tert-butylisophthalic acid and N,N′-bis-(4-pyridylmethyl) piperazine

By using 5-tert-butylisophthalic acid (H2tbip) and N,N′-bis-(4-pyridylmethyl) piperazine (bpmp), three coordination polymers formulated as {[Co(bpmp)(tbip)]·H2O}n (1), {[Ni(bpmp)1.5(tbip)(H2O)]·H2O}n (2), and {[Cd(bpmp)1.5(tbip)]·3H2O}n (3) have been synthesized under hydrothermal conditions. All complexes were characterized by single crystal X-ray diffraction analysis, powder X-ray diffraction analysis, elemental analysis, infrared spectroscopy and thermogravimetric analysis. The results show that complex 1 presents a 3D 6-connected network. Complex 2 shows a three-fold interpenetrating framework based on subunits with {46.64}-bnn hexagonal BN topology while complex 3 shows a 2D → 3D polycatenation framework containing 2D bilayer motifs as the fundamental building units. The photocatalytic properties of complexes 1 and 2 have been evaluated and the results show that they are active as a catalyst for the decomposition of Rhodamine B under visible light. The photoluminescence properties of complex 3 were also assessed in the solid state at room temperature.

Syntheses, crystal structures, and optical properties of five metal complexes constructed from a V-shaped thiophene-containing ligand and different dicarboxylate ligands.

Five new metal complexes, {[Ni(DIDP)(m-bdc)(H2O)]·5H2O}n (1), {[Zn(DIDP)(hfipbb)]·2DMA}n (2), {[Zn(DIDP)(4,4'-sdb)]·H2O}n (3), {[Co(DIDP)(p-bdc)]}n (4), and {[Co2(DIDP)(hfipbb)2]·H2O}n (5), have been synthesized by reactions of the corresponding metal ions with a V-shaped ligand 2,8-di(1H-imidazol-1-yl)dibenzothiophene (DIDP) and different aromatic dicarboxylic acids, namely isophthalic acid (m-H2bdc), terephthalic acid (p-H2bdc), 4,4'-(hexafluoroisopropylidene)bis(benzoic acid) (H2hfipbb), and 4,4'-sulfonyldicarboxylic acid (4,4'-H2sdb), respectively. The structures of the complexes were determined by X-ray single-crystal diffraction. Complex 1 is a 1D chain structure containing a one-dimensional channel along the a direction and is further extended via O-H···S hydrogen bonds and C-H···π stacking interactions into a 3D framework. Complex 2 exhibits a quasi 2D + 2D → 2D with parallel polycatenation of 2D (4, 4) nets. Complex 3 displays an unusual 2D + 2D → 3D parallel polycatenated framework based on a 2D 6(3)-hcb network. Complex 4 shows a 2D 4-connected {4(4)·6(2)}-sql network containing a one-dimensional channel along the b direction. The adjacent 2D networks are further extended via C-H···O hydrogen bonds into a 3D supramolecular framework. Complex 5 features a 2-fold interpenetrating 3D framework with a 6-connected {4(12)·6(3)} pcu topology. Furthermore, the thermal stability for 1-5 and luminescence properties of 2 and 3 have been studied. Moreover, the solid-state UV-visible spectroscopy experiments show that complexes 1-5 are all optical semiconductors with band gaps of 3.06, 3.18, 3.23, 2.98, and 3.17 eV, respectively.

Hydrothermal Synthesis, Crystal Structure and Spectroscopic Characterization of a Novel 2D → 3D Parallel Polycatenated Coordination Framework [Cd(cmb)(bix)] n

A novel entangled coordination polymer [Cd(cmb)(bix)] n (1) [H2cmb = 2,2′-(2-(carboxymethoxy)benzoic acid), bix = 1,4-bis(imidazol-1-ylmethyl)benzene], has been synthesized by hydrothermal reaction of Cd(Ac)2·2H2O, bix and H2cmb, and characterized by elemental analysis, IR spectra, PXRD, and single-crystal X-ray diffraction. The structure determination reveals that the complex 1 shows a new 2D → 3D parallel polycatenation framework based on highly undulating 2D 44 -sql layers, in which each layer is polycatenated with adjacent two others (one above and one below, DOC = 4) which have parallel but not coincident mean planes. Moreover, the thermal stability and photoluminescence property of 1 were also discussed. A novel 2D → 3D parallel polycatenated coordination polymer [Cd(cmb)(bix)] n (1), based on highly undulating 2D 44 -sql layers, has been hydrothermally synthesized and characterized. Moreover, the thermal stability and photoluminescence property of 1 were also investigated.