Showing papers on "Coordination polymer published in 2021"

Fe-Based Coordination Polymers as Battery-Type Electrodes in Semi-Solid-State Battery-Supercapacitor Hybrid Devices.

Abstract: One two-dimensional Fe-based metal-organic framework (FeSC1) and one one-dimensional coordination polymer (FeSC2) have been solvothermally prepared through the reaction among FeSO4·7H2O, the tripodal ligand 4,4',4″-s-triazine-2,4,6-triyl-tribenzoate (H3TATB), and flexible secondary building blocks p/m-bis((1H-imidazole-1-yl)methyl)benzene (bib). Given that their abundant interlayer spaces and different coordination modes, two compounds have been employed as battery-type electrodes to understand how void space and different coordination modes affect their performances in three-electrode electrochemical systems. Both materials exhibit outstanding but different electrochemical performances (including distinct capacities and charge-transfer abilities) under three-electrode configurations, where the charge storage for each electrode material is mainly dominated by the diffusion-controlled section (i ∝ v0.5) through power-law equations. Additionally, the partial phase transformations to more stable FeOOH are also detected in the long-term cycling loops. After coupling with the capacitive carbon-based electrode to assemble into the semi-solid-state battery-supercapacitor-hybrid (sss-BSH) devices, the sss-FeSC1//AC BSH device delivers excellent capacitance, superior energy and power density, and longstanding endurance as well as the potential practical property.

Multi-Mode Color-Tunable Long Persistent Luminescence in Single-Component Coordination Polymers

Abstract: Materials with tunable long persistent luminescence (LPL) properties have wide applications in security signs, anti-counterfeiting, data encrypting, and other fields. However, the majority of reported tunable LPL materials are pure organic molecules or polymers. Herein, a series of metal-organic coordination polymers displaying color-tunable LPL were synthesized by the self-assembly of HTzPTpy ligand with different cadmium halides (X=Cl, Br, and I). In the solid state, their LPL emission colors can be tuned by the time-evolution, as well as excitation and temperature variation, realizing multi-mode dynamic color tuning from green to yellow or green to red, and are the first such examples in single-component coordination polymer materials. Single-crystal X-ray diffraction analysis and theoretical calculations reveal that the modification of LPL is due to the balanced action from single molecule and aggregate triplet excited states caused by an external heavy-atom effect. The results show that the rational introduction of different halide anions into coordination polymers can realize multi-color LPL.

A half-salamo-based pyridine-containing ligand and its novel NiII com­plexes including different auxiliary ligands: syntheses, structures, fluorescence properties, DFT calculations and Hirshfeld surface analysis

Abstract: Three novel multinuclear NiII com­plexes, namely, bis{μ-2-methoxy-6-[8-(pyri­din-2-yl)-3,6-dioxa-2,7-diazaocta-1,7-dien-1-yl]phenolato}bis[thiocyanatonickel(II)], [Ni2(L)2(NCS)2], 1, bis{μ-2-methoxy-6-[8-(pyridin-2-yl)-3,6-dioxa-2,7-diazaocta-1,7-dien-1-yl]phenolato}bis[azidonickel(II)], [Ni2(L)2(N3)2], 2, and catena-poly[[{2-methoxy-6-[8-(pyridin-2-yl)-3,6-dioxa-2,7-diazaocta-1,7-dien-1-yl]phenolato}nickel(II)]-μ-dicyanamidato], [Ni(L)(dca)]n, 3 {dca is dicyanamide, C2N3, and HL is 2-methoxy-6-[8-(pyridin-2-yl)-3,6-dioxa-2,7-diazaocta-1,7-dien-1-yl]phenol, C16H17N3O4}, with a half-salamo-based pyridine-containing HL ligand have been synthesized and characterized by FT–IR, UV–Vis absorption spectroscopy, X-ray crystallography, Hirshfeld surface analysis and density functional theory (DFT) calculations. The central NiII ions in com­plexes 1–3 are hosted in the half-salamo-based N3O-donor cavity of the organic ligand. Com­plex 1 is a centrosymmetric dimer and two [Ni(L)(NCS)] units form a centrosymmetric dimeric structure, which is bridged by two phenolate O atoms. The two N atoms at the axial ends are provided by two NCS− ligands. In com­plex 1, each NiII ion has a six-coordinated octahedral geometry. Com­plex 2 is similar to 1, but they differ in that the auxiliary NCS− ligand is replaced by N3−. However, com­plex 3 is a one-dimensional coordination polymer constructed from [Ni(L)(dca)] units, which are connected by the auxiliary bidentate dca ligand via N-donor atoms. As with com­plexes 1 and 2, the NiII ion in 3 has a six-coordinated octahedral geometry.

An Open-shell, Luminescent, Two-Dimensional Coordination Polymer with a Honeycomb Lattice and Triangular Organic Radical.

Abstract: The use of organic radicals as building blocks is an effective approach to the production of open-shell coordination polymers (CPs). Two-dimensional (2D) CPs with honeycomb spin–lattices have attra...

Regulating Electrocatalytic Oxygen Reduction Activity of a Metal Coordination Polymer via d-π Conjugation.

Abstract: Non-noble transition metal complexes have attracted growing interest as efficient electrocatalysts for oxygen reduction reaction (ORR) while their activities still lack rational and effective regulation. Herein, we propose a d-π conjugation strategy for rough and fine tuning of ORR activity of TM-BTA (TM=Mn/Fe/Co/Ni/Cu, BTA=1,2,4,5-benzenetetramine) coordination polymers. By first-principle calculations, we elucidate that the strong d-π conjugation elevates the dxz /dyz orbitals of TM centers to enhance intermediate adsorption and strengthens the electronic modulation effect from substitute groups on ligands. Based on this strategy, Co-TABQ (tetramino benzoquinone) is found to approach the top of ORR activity volcano. The synthesized Co-TABQ with atomically distributed Co on carbon nanotubes exhibits a half-wave potential of 0.85 V and a specific current of 127 mA mgmetal -1 at 0.8 V, outperforming the benchmark Pt/C. The high activity, low peroxide yield, and considerable durability of Co-BTA and Co-TABQ promise their application in oxygen electrocatalysis. This study provides mechanistic insight into the rational design of transition metal complex catalysts.

A Photoluminescent Cd(II) Coordination Polymer with Potential Active Sites Exhibiting Multiresponsive Fluorescence Sensing for Trace Amounts of NACs and Fe3+ and Al3+ Ions.

Abstract: The elaborately designed π-electron-rich fluorescent ligand 1,4-bis(1-carboxymethylene-4-imidazolyl)benzene (H2L), possessing bifunctional groups including the carboxylate groups (building units) and 4-imidazoyl groups (N-donor potential active sites) has been employed to construct fluorescent coordination polymers. A luminescent sensor, namely [Cd(L)(phen)2]·5H2O (1), was obtained, which has a one-dimensional structure. The fluorescent material shows a blue emission maximum at 457 nm with a luminescence lifetime of 488 ns and a quantum yield (QY) of 4.56%. Significantly, 1 serves as a promising multiresponsive luminescent sensor to detect trace nitroaromatic compounds (NACs) with the limits of detection (LOD) of 7.21 × 10-8, 1.85 × 10-5, and 1.15 × 10-5 mol/L for 2-nitrophenol (2-NP), 3-nitrophenol (3-NP), and 4-nitrophenol (4-NP), respectively. Furthermore, CP 1 exhibits fluorescent turn-off and turn-on sensing behavior for Fe3+ and Al3+ metal ions with trace amounts of 1.05 × 10-7 and 1.13 × 10-7 mol/L, respectively. Experimental methods and theoretical calculations were employed to elucidate the sensing mechanism in detail.

A chemically stable nanoporous coordination polymer with fixed and free Cu 2+ ions for boosted C 2 H 2 /CO 2 separation

Abstract: Safely and highly selective acetylene (C2H2) capture is a great challenge, because of its highly explosive nature, as well as its nearly similar molecule size and boiling point toward the main impurity of carbon dioxide (CO2). Adsorption separation has shown a promising future. Herein, a new nanoporous coordination polymer (PCP) adsorbent with fixed and free Cu ions (termed NTU-66-Cu) was prepared through post-synthetic approach via cation exchanging from the pristine NTU-66, an anionic framework with new 3, 4, 6-c topology and two kinds of cages. The NTU-66-Cu shows significantly improved C2H2/CO2 selectivity from 6 to 32 (v/v: 1/1) or 4 to 42 (v/v: 1/4) at low pressure under 298 K, along with enhanced C2H2 capacity (from 89.22 to 111.53 cm3·g−1). More importantly, this observation was further validated by density functional theory (DFT) calculations and breakthrough experiments under continuous and dynamic conditions. Further, the excellent chemical stability enables this adsorbent to achieve recycle C2H2/CO2 separation without loss of C2H2 capacity.

Proton-conductive coordination polymer glass for solid-state anhydrous proton batteries

Abstract: Designing solid-state electrolytes for proton batteries at moderate temperatures is challenging as most solid-state proton conductors suffer from poor moldability and thermal stability. Crystal–glass transformation of coordination polymers (CPs) and metal–organic frameworks (MOFs) via melt-quenching offers diverse accessibility to unique properties as well as processing abilities. Here, we synthesized a glassy-state CP, [Zn3(H2PO4)6(H2O)3](1,2,3-benzotriazole), that exhibited a low melting temperature (114 °C) and a high anhydrous single-ion proton conductivity (8.0 × 10−3 S cm−1 at 120 °C). Converting crystalline CPs to their glassy-state counterparts via melt-quenching not only initiated an isotropic disordered domain that enhanced H+ dynamics, but also generated an immersive interface that was beneficial for solid electrolyte applications. Finally, we demonstrated the first example of a rechargeable all-solid-state H+ battery utilizing the new glassy-state CP, which exhibited a wide operating-temperature range of 25 to 110 °C.

Long-Range LMCT Coupling in EuIII Coordination Polymers for an Effective Molecular Luminescent Thermometer*.

Abstract: A design for an effective molecular luminescent thermometer based on long-range electronic coupling in lanthanide coordination polymers is proposed. The coordination polymers are composed of lanthanide ions EuIII and GdIII , three anionic ligands (hexafluoroacetylacetonate), and a chrysene-based phosphine oxide bridges (6,12-bis(diphenylphosphoryl)chrysene). The zig-zag orientation of the single polymer chains induces the formation of packed coordination structures containing multiple sites for CH-F intermolecular interactions, resulting in thermal stability above 350 °C. The electronic coupling is controlled by changing the concentration of the GdIII ion in the EuIII -GdIII polymer. The emission quantum yield and the maximum relative temperature sensitivity (Sm ) of emission lifetimes for the EuIII -GdIII polymer (Eu:Gd=1:1, Φtot =52 %, Sm =3.73 % K-1 ) were higher than those for the pure EuIII coordination polymer (Φtot =36 %, Sm =2.70 % K-1 ), respectively. Enhanced temperature sensing properties are caused by control of long-range electronic coupling based on phosphine oxide with chrysene framework.

A new silver coordination polymer based on 4,6-diamino-2-pyrimidinethiol: synthesis, characterization and catalytic application in asymmetric Hantzsch synthesis of polyhydroquinolines.

Abstract: A highly efficient and stable heterogeneous coordination polymer (CP) was successfully prepared by hydrothermal combination of silver and 4,6-diamino-2-pyrimidinethiol. The prepared coordination polymer was characterized by FT-IR, XRD, TGA, SEM, EDX, X-ray mapping and Nitrogen adsorption-desorption analysis. The prepared Ag-CP exhibit excellent catalytic activity in multicomponent Hantzsch synthesis of polyhydroquinolines under mild reaction conditions in relatively short reaction times. The heterogeneity of the catalyst was confirmed by the hot filtration test; also, the catalyst was reused for at least four times under the optimized reaction conditions without any significant loss of its catalytic activity.

Mechanics, Ionics, and Optics of Metal-Organic Framework and Coordination Polymer Glasses.

Abstract: Melt and glassy states of coordination polymers (CPs)/metal-organic frameworks (MOFs) have gained attention as a new class of amorphous materials. Many bridging ligands such as azolate, nitrile, thiocyanide, thiolate, pyridine, sulfonate, and amide are available to construct crystals with melting temperatures in the range of 60-593 °C. Here, we discuss the mechanism of crystal melting, glass structures, and mechanical properties by considering both experimental and theoretical studies. High and exclusive H+ or Li+ conductivities in moldable CP glasses have been proven in the all-solid-state devices such as fuel cells or secondary batteries. Transparent glasses with wide composition and available dopants are also attractive for nonlinear optics, photoconductivity, emission, and light-harvesting. The ongoing challenge in the field is to develop the design principles of CP/MOF melts and glasses, corresponding functions of mass (ion, electron, photon, phonon, and so forth). transport and conversion, and the integration of devices with the use of their tunable mechanical properties.

Water-Stable Zn(II) Coordination Polymers Regulated by Polysubstituted Benzenes and Their Photocatalytic Performance toward Methylene Blue Degradation Dominated by Ligand-Field Effects

Abstract: Photodegradation of organic dyes over coordination polymer (CP) photocatalysts has become one of the effective strategies for the prevention and control of water pollution, in which the energy band...

Improved Detonation Performance Via Coordination Substitution: Synthesis and Characterization of Two New Green Energetic Coordination Polymers

Abstract: In this work, a new energetic coordination polymer (ECP), [Cu(HBTI)(H2O)]n (1) (H3BTI = 4,5-bistetrazole-imidazole), was synthesized by a hydrothermal method. Due to the existence of coordination water molecules in 1, however, its energy density was limited, which led to the insufficient detonation performance. To further improve its detonation performance, [Cu(H2BTI)(NO3)]n (2) was then obtained by substituting the coordinated water molecule in 1 with nitrate through the coordination substitution reaction under acidic conditions. The structures of two ECPs were respectively characterized using X-ray single-crystal diffraction, and the theoretical density of 2 (2.227 g·cm-3) was greater than 1 (1.851 g·cm-3). Thermogravimetric analyses showed that 2 has a one-step rapid weight loss process compared with the two-step slow weight loss process of 1. The theoretical calculations indicated that the detonation performances of 2 were better than those of 1. Moreover, the promotion effects of two ECPs on the combustion decomposition of ammonium perchlorate were studied using a differential scanning calorimetry method.

Response of a Zn(II)-based metal-organic coordination polymer towards trivalent metal ions (Al3+, Fe3+ and Cr3+) probed by spectroscopic methods.

Abstract: A new zinc-based two-dimensional coordination polymer, [Zn(5-AIP)(Ald-4)]·H2O (5-AIP = 5-amino isophthalate, Ald-4 = aldrithiol-4), 1, has been synthesized at room temperature by the layer diffusion technique. Single-crystal X-ray diffraction analysis of 1 showed a two-dimensional bilayer structure. An aqueous suspension of 1 upon excitation at 300 nm displayed an intense blue emission at 403 nm. The luminescence spectra were interestingly responsive and selective to Al3+, Cr3+ and Fe3+ ions even in the presence of other interfering ions. The calculated detection limits for Al3+, Cr3+ and Fe3+ were 0.35 μM (8.43 ppb), 0.46 μM (22.6 ppb) and 0.30 μM (15.85 ppb), respectively. Notably, with the cumulative addition of Al3+ ions, the luminescence intensity at 403 nm decreased steadily with a gradual red shift up to 427 nm. Afterward, this red shifted peak showed a turn-on effect upon further addition of Al3+ ions. On the other hand, for Cr3+ and Fe3+ ions, there was only drastic luminescence quenching and a large red shift up to 434 nm. This indicated the formation of a complex between 1 and these metal ions, which was also supported by the UV-Visible absorption spectra of 1 that showed the appearance of a new band at 280 nm in the presence of these three metal ions. The FTIR spectra revealed that these ions interacted with the carboxylate oxygen atom of 5-AIP and the nitrogen atom of the Ald-4 ligand in the structure. The luminescence lifetime decay analysis manifested that a charge-transfer type complex was formed between 1 and Cr3+ and Fe3+ ions that resulted in huge luminescence quenching due to the efficient charge transfer involving the vacant d-orbitals, whereas for Al3+ ions having no vacant d-orbital, turn-on of luminescence occurred because of the increased rigidity of 1 upon complexation.

Colocalization of light harvesting and catalytic units in a ‘soft’ coordination polymer hydrogel toward visible-light driven photocatalytic hydrogen production

Abstract: Colocalization of essential molecular components in a solvated soft supramolecular assembly towards realizing visible-light-driven hydrogen evolution would be an exciting approach for sustainable energy by generating clean solar fuel. In this study, we report the preparation and characterization of a coordination polymer gel (Zn-TPY-ANT CPG) formed by the self-assembly of Zn2+ and an anthracene–terpyridine based low molecular weight gelator (TPY-ANT LMWG). The 1D nanofibrous CPG in the hydrogel state shows the potential to perform visible-light-driven (400–750 nm) photocatalytic water reduction and produce a considerable amount of hydrogen (12.02 mmol g−1 in 22 h). Furthermore, H2 evolution can be enhanced significantly (18.03 mmol g−1 in 22 h) upon illumination with the full-range of light (290–750 nm). In this supramolecular assembly, the ANT unit acts as a light-harvesting moiety whereas the [Zn(TPY)2]2+ center acts as a catalytic site. We believe that such a design of soft hybrid materials would have a positive impact on developing a non-precious, stable, and recyclable photocatalyst material for H2 production.

Identifying the liquid and glassy states of coordination polymers and metal–organic frameworks

Abstract: The field of metal-organic frameworks (MOFs) is still heavily focused upon crystalline materials. However, solid-liquid transitions in both MOFs and their parent coordination polymer family are now receiving increasing attention due to the largely unknown properties of both the liquid phase and the glasses that may be formed upon melt-quenching. Here, we argue that the commonly reported concept of 'thermal stability' in the hybrid materials field is insufficient. We present several case studies of the use of differential scanning calorimetry alongside thermogravimetric analysis to prove, or disprove, the cooperative phenomena of melting in several MOF families.