Showing papers on "Coordination polymer published in 2019"

Carbon dioxide capture and efficient fixation in a dynamic porous coordination polymer

Abstract: Direct structural information of confined CO2 in a micropore is important for elucidating its specific binding or activation mechanism. However, weak gas-binding ability and/or poor sample crystallinity after guest exchange hindered the development of efficient materials for CO2 incorporation, activation and conversion. Here, we present a dynamic porous coordination polymer (PCP) material with local flexibility, in which the propeller-like ligands rotate to permit CO2 trapping. This process can be characterized by X-ray structural analysis. Owing to its high affinity towards CO2 and the confinement effect, the PCP exhibits high catalytic activity, rapid transformation dynamics, even high size selectivity to different substrates. Together with an excellent stability with turnover numbers (TON) of up to 39,000 per Zn1.5 cluster of catalyst after 10 cycles for CO2 cycloaddition to form value-added cyclic carbonates, these results demonstrate that such distinctive structure is responsible for visual CO2 capture and size-selective conversion. Porous coordination polymers that possess structural flexibility show great promise for gas adsorption and catalysis. Here the authors synthesize a dynamic porous coordination polymer with rotating ligands that permit effective CO2 trapping, and demonstrate subsequent CO2 cycloaddition to epoxides.

A bio-inspired coordination polymer as outstanding water oxidation catalyst via second coordination sphere engineering.

Abstract: First-row transition metal-based catalysts have been developed for the oxygen evolution reaction (OER) during the past years, however, such catalysts typically operate at overpotentials (η) significantly above thermodynamic requirements. Here, we report an iron/nickel terephthalate coordination polymer on nickel form (NiFeCP/NF) as catalyst for OER, in which both coordinated and uncoordinated carboxylates were maintained after electrolysis. NiFeCP/NF exhibits outstanding electro-catalytic OER activity with a low overpotential of 188 mV at 10 mA cm−2 in 1.0 KOH, with a small Tafel slope and excellent stability. The pH-independent OER activity of NiFeCP/NF on the reversible hydrogen electrode scale suggests that a concerted proton-coupled electron transfer (c-PET) process is the rate-determining step (RDS) during water oxidation. Deuterium kinetic isotope effects, proton inventory studies and atom-proton-transfer measurements indicate that the uncoordinated carboxylates are serving as the proton transfer relays, with a similar function as amino acid residues in photosystem II (PSII), accelerating the proton-transfer rate. Proton-coupled electron transfer (PCET) process is very important for water oxidation catalysis. Here, the authors introduced uncoordinated carboxylate in the second-coordination-sphere of Ni-Fe coordination polymer catalyst as an internal base to promote the water oxidation kinetics by such PCET process.

Cobalt(II)-Based 3D Coordination Polymer with Unusual 4,4,4-Connected Topology as a Dual-Responsive Fluorescent Chemosensor for Acetylacetone and Cr2O72.

Abstract: A cobalt(II) coordination polymer with an unusual 4,4,4-connected network was hydrothermally synthesized and observed with high thermal, solvent, and pH stabilities. This polymer can serve as the first dual-responsive fluorescent chemosensor for the selective detection of acetylacetone and Cr2O72- ion (pH 3.0) in aqueous systems.

A One-Dimensional π-d Conjugated Coordination Polymer for Sodium Storage with Catalytic Activity in Negishi Coupling.

Abstract: π-d Conjugated coordination polymers (CCPs) have attracted much attention for various applications, although the chemical states and structures of many CCPs are still blurry. Now, a one-dimensional (1D) π-d conjugated coordination polymer for high performance sodium-ion batteries is presented. The chemical states of the obtained coordination polymer are clearly revealed. The electrochemical process undergoes a three-electron reaction and the structure transforms from C=N double bonds and NiII to C-N single bonds and NiI , respectively. Our unintentional experiments provided visual confirmation of NiI . The existence of NiI was further corroborated by its X-ray absorption near-edge structure (XANES) and its catalytic activity in Negishi cross-coupling.

A Two‐Dimensional Iron(II) Coordination Polymer with Synergetic Spin‐Crossover and Luminescent Properties

Abstract: A composite material, {[Fe(L)(TPPE)0.5 ]⋅3 CH3 OH}n , has been constructed by integrating the spin-crossover (SCO) subunit FeII {diethyl(E,E)-2,2'-[1,2-phenyl-bis(iminomethylidyne)]bis(3-oxobutanoate)-(2-)-N,N',O3 ,O3 '} and the highly luminescent connector 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)-ethene. Its structure contains four staggered 4×4 layers and intercalated methanol. The packing is dominated by considerable H-bonds either between adjacent layers and between layers and guests. A crystal-structure transformation was detected upon removal of the guest molecules. The SCO transition of the solvated crystals is centered at ca. 215 K with a non-symmetrical hysteresis of 25 K wide, and the desolvated [Fe(L)(TPPE)0.5 ]n exhibits gradual SCO without hysteresis. Intriguingly, the intensity of the fluorescence at 460 nm for the latter is maximized at the SCO transition. The energy transfer between luminescent and SCO entities is achievable as confirmed by theoretical calculations.

Supramolecular Aggregate of Cadmium(II)-Based One-Dimensional Coordination Polymer for Device Fabrication and Sensor Application.

Abstract: A novel mixed ligand one-dimensional coordination polymer (1D CP), {[Cd2(adc)2(4-nvp)6]·(MeOH)·(H2O)} n (1; H2adc = 9,10-anthracenedicarboxylic acid, and 4-nvp = 4-(1-naphthylvinyl)pyridine), has been synthesized and structurally characterized by single crystal X-ray crystallography. The 1D polymer undergoes supramolecular aggregation via hydrogen bonding, C-H···π, and π···π interactions. Interestingly, compound 1 shows increasing conductivity upon irradiation of light. Therefore, it has the potential to be used in optoelectronic devices. Moreover, the supramolecular assembly of 1 specifically detects Cr3+ cation in the presence of other competitive analytes. Most importantly, compound 1 exhibits fascinating turn-on Cr3+ sensing, which seems to be an ornament in the field of sensing application.

Maximizing Ag Utilization in High-Rate CO2 Electrochemical Reduction with a Coordination Polymer-Mediated Gas Diffusion Electrode

Abstract: We report the preparation and electrocatalytic performance of silver-containing gas diffusion electrodes (GDEs) derived from a silver coordination polymer (Ag-CP). Layer-by-layer growth of the Ag-C...

Highly responsive nature of porous coordination polymer surfaces imaged by in situ atomic force microscopy.

Abstract: The ability of porous coordination polymers to undergo reversible structural transformations in response to the presence of guest molecules has been intensively investigated for applications such as molecular separation, storage, sensing and signalling processes. Here we report on the direct observation of the highly guest-responsive nature of the surface of a single-crystalline porous coordination polymer, which consists of paddlewheel zinc clusters and two types of ligand, by in situ liquid-phase atomic force microscopy. Observations were carried out in solution at constant temperature (28 °C) by high-speed atomic force microscopy with lattice resolution. A sharp and reversible response to the presence or absence of biphenyl guest molecules was observed, under conditions that can scarcely induce the transformation of the bulk crystal. Additionally, by modulating the surface coordination equilibrium, layer-by-layer delamination events were captured in real time at every ~13 s per frame. Some porous coordination polymers (PCPs) are known to be flexible and guest-responsive. Now, the guest-induced sharp, reversible structural transformation of the surface of a single-crystalline PCP has been visualized by in situ liquid-phase atomic force microscopy. This local response occurred at a guest concentration that was too low to trigger changes to the bulk crystal.

A Multistimulus Responsive Porous Coordination Polymer: Temperature-Mediated Control of Solid-State [2+2] Cycloaddition.

Abstract: Either of two different isomeric products can be selectively obtained by photochemical [2+2] cycloaddition of 1,4-bis[2-(4-pyridyl)ethenyl]-benzene within a porous coordination polymer (PCP). The cycloaddition product obtained depends on the temperature at which irradiation occurs. A rare temperature-induced phase transition alters the conformation of the photoactive ligand in the PCP, and thereby the positions at which cycloaddition occurs. We show that the multistimulus responsive nature of this particular PCP is due to the flexibility of the ligands employed.

Three-in-one is really better: exploring the sensing and adsorption properties in a newly designed metal-organic system incorporating a copper(ii) ion.

Abstract: A 2-D copper(II)-based coordination polymer, [Cu(SCN)(hmp)]n CP (1), was crystallized via the slow evaporation method after the reaction of CuSO4·5H2O, 2-pyridinemethanol (hmpH), sodium thiocyanate and sodium hydroxide in water for functional applications. CP (1) was characterized via elemental analysis, FTIR, PXRD, magnetic, EPR, crystallographic and TGA studies. The crystal structure and EPR data confirmed a square pyramidal geometry around the Cu(II) ions. The topological analysis revealed that CP 1 has a {6^3} point symbol with a [6.6.6] extended point symbol and 3-c net, uninodal net having hcb and Shubnikov hexagonal plane net/(6,3) type of uncommon topology. The magnetic studies suggested the strong antiferromagnetic nature of CP (1). The fluorescence sensing property of CP (1) was investigated with different nitro aromatic compounds and hazardous metal ions. CP (1) demonstrated high selectivity and sensitivity towards nitrobenzene, even in the presence of other competitive nitro aromatics. In addition, CP (1) showed excellent selectivity and sensitivity toward Fe3+ over other metal ions. The possible detection mechanisms were proposed employing UV-visible and fluorescence spectroscopy and DFT calculations. CP (1) also showed excellent recyclability towards both analytes, and its initial intensity was almost regained after several washings. Moreover, CP (1) acted as an excellent adsorbent material for natural dyes with different charges and sizes, i.e., methylene blue (MB), methyl orange (MO) and Rhodamine-B. Furthermore, CP (1) was utilized repeatedly for the effective adsorption of MB from wastewater without significant loss in its adsorption capacity. Hence, the present CP (1) was designed to relate coordination chemistry with various functional applications of interest.

Metalo Hydrogen-Bonded Organic Frameworks (MHOFs) as New Class of Crystalline Materials for Protonic Conduction.

Abstract: Recently, proton conduction has been a thread of high potential owing to its wide applications in fuel-cell technology. In the search for a new class of crystalline materials for protonic conductors, three metalo hydrogen-bonded organic frameworks (MHOFs) based on [Ni(Imdz)6 ]2+ and arene disulfonates (MHOF1 and MHOF2) or dicarboxylate (MHOF3) have been reported (Imdz=imidazole). The presence of an ionic backbone with charge-assisted H-bonds, coupled with amphiprotic imidazoles made these MHOFs protonic conductors, exhibiting conduction values of 0.75×10-3 , 3.5×10-4 and 0.97×10-3 S cm-1 , respectively, at 80 °C and 98 % relative humidity, which are comparable to other crystalline metal-organic framework, coordination polymer, polyoxometalate, covalent organic framework, and hydrogen-bonded organic framework materials. This report initiates the usage of MHOF materials as a new class of solid-state proton conductors.

Persistent Superprotonic Conductivity in the Order of 10−1 S·cm−1 Achieved Through Thermally Induced Structural Transformation of a Uranyl Coordination Polymer

Abstract: Despite tremendous efforts being made in the exploration of new high-performance proton-conducting materials, studies on systems with superprotonic conductivity higher than 10−1 S·cm−1 remain scarc...

A luminescent sensor based on a Zn(II) coordination polymer for selective and sensitive detection of NACs and Fe3+ ions

Abstract: To design an effective fluorescence probe for sensing nitroaromatic compounds (NACs) and metal ions, a novel two-dimensional (2D) coordination polymer, {Zn2(NO3)2(4,4′-bpy)2(TBA)} (1) {H2TBA = 4-(1H-tetrazol-5-yl)-benzoic acid, 4,4′-bpy = 4,4′-bipyridine} was synthesized via a hydrothermal method. As expected, 1 presented varying degrees of fluorescence intensity changes for detecting and recognizing trace NACs with high selectivity and sensitivity in water solution. Moreover, 1 not only exhibited a highly selective fluorescence quenching effect on Fe3+ ions in aqueous solution, but could also resist the interference of various other metal ions. In addition, it has been found that the fluorescence quenching mechanisms among NACs and Fe3+ ions are mainly related to the interactions between the host group and guest molecules by energy and electron transfer.

Functional Two-Dimensional Coordination Polymer ExhibitingLuminescence Detection of Nitroaromatics

Abstract: A polyfluorinated-aromatic carboxylic acid has been designed and synthesized by the acylation reaction, tetrafluoro-bis(3,5-dicarboxyphenyl)terephthalamide (H4 bdtfa), which assembled with Zn2+ ions in the mixed solvents of DMF, py, and H2O under solvothermal conditions to produce a two-dimensional (2D) coordination polymer (CP), {[Zn2(bdtfa)(py)3(H2O)]·2DMF}n (1), (py = pyridine, DMF = N,N′-dimethylmethanamide). The final structure has been carefully characterized by various methods including single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), infrared (IR) spectroscopy, and thermogravimetric analysis. Two types of four-coordinated Zn2+ centers present a 2D “sql”-type layer through bdtfa4– ligands, and the adjacent layers are connected through hydrogen bonds and π···π stacking interactions to produce a three-dimensional supramolecular framework. Luminescent results reveal that CP 1 can be regarded as a highly sensitive sensor for detecting nitroaromatics based on the fluorescence quenching...

[Cu3(C6Se6)] n : The First Highly Conductive 2D π-d Conjugated Coordination Polymer Based on Benzenehexaselenolate.

Abstract: Nanocrystals of a 2D π-d conjugated copper bis(diselenolene) coordination polymer (Cu-BHS, BHS = benzenehexaselenolate) are synthesized via a simple homogeneous reaction between cupric ions and benzenehexaselenol (H6BHS). Its 2D extended hexagonal lattice is confirmed by powder X-ray diffraction, and further characterized by scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The electrical conductivity measured on compressed powder sample reaches 110 S cm-1 at 300 K, which is among the highest value ever reported for coordination polymers. Furthermore, the intrinsic metallic characteristics of Cu-BHS are confirmed by ultraviolet photoelectron spectroscopy and band structure calculation.

A Newly Synthesized Heterobimetallic NiII-GdIII Salamo-BDC-Based Coordination Polymer: Structural Characterization, DFT Calculation, Fluorescent and Antibacterial Properties

Abstract: A unprecedented hetero-bimetallic 3d-4f BDC-salamo-based coordination polymer, [(L)Ni(BDC)Gd(NO3)(DMF)] was prepared and validated via elemental analyses, IR and UV–Visible absorption spectra, DFT calculation, and X-ray crystallography. The six-coordinated Ni1 ion lies at the N2O2 donor site of the L2− moiety, and one DMF O atom and carboxylate O atom occupy, collectively, the axial positions, and form a twisted octahedron. The nine-coordinated Gd1 ion consists of three oxygen atoms (O12, O13, and O14) of two carboxylate groups, two oxygen atoms (O8 and O9) derived from one bidentate nitrate group, and an O2O2 coordination site (O1, O2, O6, and O5) of the L2− unit, forming a twisted three-capped triangular prism coordination geometry. Compared to the ligand (H2L), the fluorescence intensity decreases due to the coordination of metal ions. Meanwhile, the antibacterial activities are researched.

A water-stable La-MOF with high fluorescence sensing and supercapacitive performances.

Abstract: A 3D lanthanide coordination polymer {[La(SIP)(H2O)3]·H2O}n (La-MOF) was synthesized successfully by the solvothermal reaction of La(NO3)3·6H2O and 5-sulfoisophthalic acid monosodium salt (NaH2SIP). In particular, two oxygen atoms of sulfate participate in the coordination, which is unusual in all the complexes. La-MOF was characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction, thermal-gravimetric analysis, and X-ray photoelectron spectroscopy. La-MOF shows excellent water stability and chemical stability in a broad pH range from 2 to 13. Moreover, the fluorescence and sensing properties of La-MOF were invsetigated in detail via its titration and cycling processes, revealing its highly efficient and selective quenching responses and good recyclability for the detection of Fe3+, Cr2O72- and CrO42- ions. In addition, La-MOF possesses an outstanding specific capacitance of 213 F g-1 at 0.5 A g-1. It still retains 92% of the original capacitance after 2000 cycles, exhibiting remarkable long-term cycling stability and reversibility; therefore, the electrode material based on La-MOF is a competitive and promising candidate for application in supercapacitors.

Cd(II) Based Coordination Polymer Series: Fascinating Structures, Efficient Semiconductors, and Promising Nitro Aromatic Sensing

Abstract: Three Cd(II) based coordination polymers (CPs) (1–3) are designed using 3-aminoquinoline and 5-aminoquinoline based Schiff base ligands and thiocyanate and dicyanamide as bridging ligands. Pseudoha...

Self-assembled energetic coordination polymers based on multidentate pentazole cyclo -N 5 –

Abstract: Coordination to form polymer is emerging as a new technology for modifying or enhancing the properties of the existed energetic substances in energetic materials area. In this work, guanidine cation CN3H6+ (Gu) and 3-amino-1,2,4-triazole C2H4N4 (ATz) were crystallized into NaN5 and two novel energetic coordination polymers (CPs), (NaN5)5[(CH6-N3)N5](N5)3– ( 1 ) and (NaN5)2(C2H4N4) ( 2 ) were prepared respectively via a self-assembly process. The crystal structure reveals the co-existence of the chelating pentazole anion and organic component in the solid state. In polymer 1 , Na+ and N5– were coordinated to form a cage structure in which guanidine cation [C(NH2)3]+ was trapped; for polymer 2 , a mixed-ligand system was observed; N5– and ATz coordinate separately with Na+ and form two independent but interweaved nets. In this way, coordination polymer has been successfully utilized to modify specific properties of energetic materials through crystallization. Benefiting from the coordination and weak interactions, the decomposition temperatures of both polymers increase from 111°C (1D structure [Na(H2O)(N5)]∙2H2O) to 118.4 and 126.5°C respectively. Moreover, no crystallized H2O was generated in products to afford the anhydrous compounds of pentazole salts with high heats of formation (> 800 kJ mol–1). Compared to traditional energetic materials, the advantage in heats of formation is still obvious for the cyclo -N5– based CPs, which highlights cyclo -N5– as a promising energetic precursor for high energy density materials (HEDMs).

Synthesis of a Zn(II)-based 1D zigzag coordination polymer for the fabrication of optoelectronic devices with remarkably high photosensitivity

Abstract: A Zn(II) based one-dimensional coordination polymer (1D CP), [Zn4(adc)4(4-cltpy)4]·CH3OH·2H2O (1) (H2adc = acetylenedicarboxylic acid and 4-cltpy = 4′-chloro-[2,2′;6′,2′′] terpyridine), has been synthesized by a slow diffusion method and characterized by X-ray crystallography. Here, the linear adc ligand acts as the linker between two Zn(II) centers and a chelating 4-cltpy ligand is appended at the metal node. The connectivity of the ligands with metal ions generates a 1D zigzag polymeric chain. The zigzag chains are aggregated through various secondary interactions to construct a three-dimensional (3D) structure. The optical band gap has been determined and correlated with the theoretical band gap calculated by density functional theory (DFT) computations, which reveals that compound 1 possesses semiconducting properties. Moreover, compound 1 shows remarkably high photosensitivity (PS = 1134) upon illumination by light. Therefore, compound 1 has the potential to be used in optoelectronic devices and solar cells.

Mechanochemical Synthesis of a New Triptycene-Based Imine-Linked Covalent Organic Polymer for Degradation of Organic Dye

Abstract: In the present work, a novel triptycene-based imine-linked covalent organic polymer (TP-COP) was designed and synthesized via room-temperature, solvent-free mechanochemical grinding. The as-synthes...

Nickel(II)-Based Two-Dimensional Coordination Polymer Displaying Superior Capabilities for Selective Sensing of Cr(VI) Ions in Water

Abstract: Three fluorescent coordination polymers (CPs) including [Zn(ppvppa)(5-NO2-1,3-BDC)(H2O)] (1), [Cd(ppvppa)2(2,5-FDC)]·1.5H2O (2), and [Ni(ppvppa)(5-NO2-1,3-BDC)(H2O)]·0.5MeCN (3) (ppvppa = dipyridin...