Strong Coordination Bonds Research Articles

Plastic bending in a semiconducting coordination polymer crystal enabled by delamination

Coordination polymers (CPs) are a class of crystalline solids that are considered brittle, due to the dominance of directional coordination bonding, which limits their utility in flexible electronics and wearable devices. Hence, engineering plasticity into functional CPs is of great importance. Here, we report plastic bending of a semiconducting CP crystal, Cu-Trz (Trz = 1,2,3-triazolate), that originates from delamination facilitated by the discrete bonding interactions along different crystallographic directions in the lattice. The coexistence of strong coordination bonds and weak supramolecular interactions, together with the unique molecular packing, are the structural features that enable the mechanical flexibility and anisotropic response. The spatially resolved analysis of short-range molecular forces reveals that the strong coordination bonds, and the adaptive C–H···π and Cu···Cu interactions, synergistically lead to the delamination of the local structures and consequently the associated mechanical bending. The proposed delamination mechanism offers a versatile tool for designing the plasticity of CPs and other molecular crystals.

Mechanically robust, instant self-healing polymers towards elastic entropy driven artificial muscles

Despite the substantial developments, it remains a huge challenge for the fabrication of soft actuators to achieve the systematic integrations of good actuating performance, high mechanical strength and self-healing ability at ambient temperature. Herein, we report the preparation of robust self-healing polymeric materials by introducing strong coordination bonds to the polymers with multiple hydrogen bonds and anisotropic chain structures. Due to the synergistic effect between the weak hydrogen and strong coordination bonds, the resultant polymer exhibits excellent mechanical strength (12.68 MPa) and instant (30 s) self-healing ability with a high healing efficiency of ca. 95 % at ambient temperature. Thanks to the entropic elasticity trapped by the anisotropic polymer chains, the resultant anisotropic polymer can be used as thermal-triggered artificial muscles with a tensile stroke of ca. 12 %. Even the healed sample can still achieve a tensile stroke of ca. 11 % repeatedly.

Coordination Anchoring Effect Promoting the Interfacial Stability and Electrochemical Performance of LiNi0.8Co0.1Mn0.1O2 Cathode Material for Lithium‐Ion Batteries

LiNi0.8Co0.1Mn0.1O2 (NCM811), as a typical nickel‐rich ternary material, has attracted wide attention due to its high discharge specific capacity. However, the strict storage environment and interface instability caused by residual alkali on the surface limit the further development. Surface coating is usually used to modify the surface of cathode materials to improve interface stability. However, traditional inorganic coating is easy to fall off due to a lack of stable chemical bonding, and the interaction force of previous organic coating has not been thoroughly studied. Herein, polyvinyl pyrrolidone with carbonyl functional groups is introduced on the surface of NCM811, and the carbonyl group forms strong coordination bonds with transition metal ions, that is, the organic coating layer forms stable coordination anchoring with the cathode material, which greatly reduces the situation where the coating layer is easy to fall off. At the same time, the implanted organic coating can inhibit the dissolution of transition metal ions and mitigate the side reaction. The results show that the capacity retention rate of the modified material reaches 86.82% after 50 cycles at 1 C rate. This novel surface modification strategy provides a new insight for the modification of high‐nickel cathode materials.

Photoinduced loading of electron-rich Cu single atoms by moderate coordination for hydrogen evolution

Single-atom catalysts offer maximal atom utilization efficiencies and high-electronegativity heteroatoms play a crucial role in coordinating reactive single metal atoms to prevent agglomeration. However, these strong coordination bonds withdraw electron density for coordinated metal atoms and consequently affect their catalytic activity. Herein we reveal the high loading (11.3 wt%) and stabilization of moderately coordinated Cu-P3 structure on black phosphorus support by a photochemical strategy with auxiliary hydrogen. Single-atom Cu sites with an exceptional electron-rich feature show the triangle {G}_{{{{{{rm{H}}}}}}*} close to zero to favor catalysis. Neighboring Cu atoms work in synergy to lower the energy of key water adsorption and dissociation intermediates. The reported catalyst shows a low overpotential of only 41 mV at 10 mA cm−2 and Tafel slope of 53.4 mV dec−1 for the alkaline hydrogen evolution reaction, surpassing both isolated Cu single atoms and Cu nanoclusters. The promising materials design strategy sheds light on the design and fabrication of high-loading single metal atoms and the role of neighboring single atoms for enhanced reaction kinetics.

Non-Flammable Sodium Asymmetric Imide Salt-Based Deep Eutectic Solvent for Supercapacitor Applications.

This study reports two deep eutectic solvents (DESs) based on alkaline imide salts with asymmetric anions as functional electrolytes for supercapacitor (SC) application. The eutectic mixture of sodium (fluorosulfonyl) (trifluoromethanesulfonyl) imide (NaFTFSI) or sodium cyano-trifluoromethanesulfonyl imide (NaTFSICN) with ethylene carbonate (EC) delivers a non-flammable and stable liquid. The eutectic diagrams of the electrolytes directed to an optimal composition (wsalt =0.25), hinging to that of conventional carbonate-based electrolytes, i. e., 1 mol L-1 . The volumetric properties of the DESs revealed a "stacking" effect, reflecting a strong coordination bond between the imide and EC anions without solvating the Na+ cations. The DES transport properties (i. e., viscosity, conductivity, and ionicity) and temperature variations designate a high organization, similar to ionic liquids. The DESs, when coupled with activated carbon electrodes in a two-electrode symmetric configuration, yield specific capacities of 150 F g-1 at a normalized current density of 0.5 A g-1 (and 120 F g-1 at 2 A g-1 ). The SC maintained 80 % of its initial capacity beyond 100 h of floating at an operating voltage of 2.4 V and showed a 150 mV per hour potential loss under self-discharge. The devised eutectic mixtures offer a promising new pathway for simple, safe, and effective electrolytes for SC applications.

Solvent Gaming Chemistry to Control the Quality of Halide Perovskite Thin Films for Photovoltaics.

Research on solvent chemistry, particularly for halide perovskite intermediates, has been advancing the development of perovskite solar cells (PSCs) toward commercial applications. A predictive understanding of solvent effects on the perovskite formation is thus essential. This work systematically discloses the relationship among the basicity of solvents, solvent-contained intermediate structures, and intermediate-to-perovskite α-FAPbI3 evolutions. Depending on their basicity, solvents exhibit their own favorite bonding selection with FA+ or Pb2+ cations by forming either hydrogen bonds or coordination bonds, resulting in two different kinds of intermediate structures. While both intermediates can be evolved into α-FAPbI3 below the δ-to-α thermodynamic temperature, the hydrogen-bond-favorable kind could form defect-less α-FAPbI3 via sidestepping the break of strong coordination bonds. The disclosed solvent gaming mechanism guides the solvent selection for fabricating high-quality perovskite films and thus high-performance PSCs and modules.

Cabbage extract as an eco-friendly corrosion inhibitor for X70 steel in hydrochloric acid medium

This work explored the feasibility of cabbage extract (CAE) as an environmentally friendly corrosion inhibitor to inhibit the corrosion of X70 steel in 1 M hydrochloric acid solution. Potentiodynamic polarization and electrochemical impedance spectroscopy combined with scanning electron microscope (SEM), atomic force microscope (AFM) were used to inspect anti-corrosion ability of CAE. In addition, X-ray photoelectron spectroscopy (XPS), density function theory (DFT) and molecular dynamics (MD) methods were used to illustrate the anti-corrosion mechanism. The experimental results showed that CAE has excellent protection performance for X70 steel in HCl solution, and its inhibition efficiency could reach 95.37% (298 K), 95.87% (308 K) and 93.36% (318 K) respectively. XPS results also showed that the adsorption is mainly due to the strong coordination bond between Fe-N. This study provides a new window for eco-friendly corrosion inhibitors for pipeline steel that need to be cleaned with acid solutions.

Ultraselective, ultrasensitive, point-of-care electrochemical sensor for detection of Hg(II) ions with electrospun-InZnO nanofibers

Mercury is one of the top three most hazardous substances (Agency for Toxic Substances and Disease Registry). It is among one of the highly toxic water pollutants causing damage to the brain, lungs, nervous system, and many other vital human organs. Hence, detecting Hg(II) at the lowest concentration (picomolar-femtomolar) is highly desirable to avoid adverse health effects. This article outlines an insightful electrochemical sensor platform for ultraselective sensing of Hg(II) with Self Assembled Monolayers (SAM) of mercaptosuccinic acid (MSA) cross-linked pyridinedicarboxylic acid (PDCA) on top of indium doped ZnO nanofibers (InZnO-NF). The sensor achieves a limit of detection (LOD) 3.13 fM. To improve charge transport properties, indium-doping is used. The MSA-PDCA combination with multifunctional strategy has excellent selectivity towards targeted Hg(II) ions because of its highest stability constant and strong coordinate covalent bond of carboxyl groups (–COOH) with Hg(II). The interaction of Hg(II) ions with InZnO/MSA-PDCA is observed in terms of a change of charge transfer resistance (Rct), which is used as a primary sensing parameter and directly proportional to the mass of targeted Hg(II) ions. The proposed portable electrochemical sensor is the first of its kind capable of ultrasensitive detection of Hg(II) ions in the femtomolar range and useful as a Point-of-care testing platform.

Rational Design of Coordination Bond Connected Metal Organic Frameworks/MXene Hybrids for Efficient Solar Water Splitting

AbstractMetal organic frameworks (MOFs) have attracted great interest in photocatalysis, but their activity is hampered by the issue of severe carrier recombination. Here, through a carboxyl group assisted coordination route, MXene decorated with carboxyl groups provides chelation sites enabling coordination with UiO‐66‐NH2(Zr/Ti) (UZT) to fabricate a tightly connected UiO‐66‐NH2(Zr/Ti)/carboxyl‐functionalized MXene (UZT/CFMX) heterostructure. This is the first instance of direct chemical bonding of MOFs‐involved heterostructure via a coordination bond. The critical role of decorated carboxyl groups can be determined so that 1) these can help to establish a strong coordination bond between two materials; 2) act as bridge to promote the electrons transfer from MOFs to MXene, thus relieving carrier recombination, and 3) most interestingly, the carbon atom on the carboxyl group forms a bond with the oxygen from water stimulating the water to dissociate into OH* and H*, thus adding additional reaction pathways for promoting photocatalytic water splitting. Accordingly, the resulting UZT/CFMX shows efficient solar‐driven photocatalytic performance for water splitting. The H2 evolution rate is as high as 2187 µmol g−1 h−1, 20 times higher than that of UZT and 4 times higher than that of UiO‐66‐NH2 (Zr/Ti)/MXene (UZT/MX), also surpassing the majority of reported MOF‐based photocatalysts.

Selective hydrogenation of glucose to sorbitol with tannic acid-based porous carbon sphere supported Ni–Ru bimetallic catalysts

Ni–Ru bimetallic porous carbon sphere (Ni–Ru@PCS) catalysts were synthesized via formaldehyde-assisted, metal-coordinated crosslinking sol–gel chemistry, in which biomass-derived tannic acid and F127 surfactant were used as carbon precursor and soft template, respectively, and Ni2+ and Ru3+ were used as cross-linkers. In the developed method, Ni–Ru particles became uniformly dispersed in the carbon skeleton due to strong coordination bonds between metal ions (Ni2+ and Ru3+) and tannic acid molecules and bimetal interactions. The as-synthesized Ni–Ru10:1@PCS catalyst with a loading Ni:Ru mole ratio of 10:1 was applied for the selective hydrogenation of glucose to sorbitol, and provided 99% glucose conversion with a sorbitol selectivity of 100% at 140 °C in 150 min reaction time and exhibited good stability and recyclability in which sorbitol yield remained at 98% after 4 cycles with little or no metal agglomeration. The catalyst was applied to glucose solutions as high as 20 wt% with 97% sorbitol yields being obtained at 140 °C in 20 h. The developed bimetallic porous carbon sphere catalysts take advantage of sustainably-derived materials in their structure and are applicable to related biomass conversion reactions.

Effect of a lone electron pair and tetrel interactions on the structure of Pb(II) CPs constructed from pyrimidine carboxylates and auxiliary inorganic ions

Three new Pb(II) coordination polymers (CPs) of pyrimidine-2-carboxylate ligand and different anionic co-ligands (perchlorate, chloride and nitrate) were synthesized and characterized by physicochemical (CHN, FT-IR, TG) and structural (SC-XRD) methods. Considering only strong primary coordination bonds the Pb(II) centres in all three complexes are hemidirectionally coordinated by organic ligands due to stereochemical activity of a lone electron pair. The Pb nodes and ligand linkers formed single- or double-layered 2D networks with honeycomb-like topology. The primary coordination sphere is sterically suitable for establishing the interactions at longer distances, where Pb centre act as Lewis acid. The MEP calculations confirmed the presence of a σ-hole in the proximity of Pb centres. Thus, all the Pb centres participate in Pb···O or Pb···Cl tetrel interactions with auxiliary inorganic ions, which together with secondary interactions of ligands and water molecules extended the structures into 3D supramolecular assemblies. The QTAIM calculations allowed for estimation of the energy of primary and secondary/tetrel interactions and to propose the theoretical criteria based on the |VBCP|/GBCP, HBCP/ρBCP, and DI parameters for distinguishing among interactions.

A facile preparation of highly dispersed ultrasmall CeO2 clusters on g-C3N4 decorated TiO2 for efficient photooxidation of Hg0

Elemental mercury (Hg0) is the most difficult mercury species to remove from the flue gas. Photocatalysts of transition metal oxide modified TiO2 can effectively remove Hg0. However, the metal oxide easily aggregates into large nanoparticles, reducing the atom utilization efficiency and photocatalytic activity. We presented a facile strategy of employing g-C3N4 as an anchor to successfully load highly dispersed ultrasmall CeO2 clusters on g-C3N4/TiO2. Moreover, the mechanism of anchoring CeO2 clusters and charge transfer of the ternary photocatalyst were explored in-depth. The results demonstrated that at 250 °C, the photooxidation efficiency of Hg0 by CeO2-g-C3N4/TiO2 was several times higher than that of CeO2/TiO2, TiO2, and g-C3N4. The cavity of the tri-s-triazine ring anchored small CeO2 clusters via strong Ce-N coordination bonds. A combined type II and Z-scheme transport paths accelerated the separation of photogenerated electron holes. This research offers valuable surface engineering strategy for highly dispersed ultrasmall cluster decorated TiO2.

A Strong and Rigid Coordination Adaptable Network that Can Be Reprocessed and Recycled at Mild Conditions

A Strong and Rigid Coordination Adaptable Network that Can Be Reprocessed and Recycled at Mild Conditions

Stretchable Hydrogels with Low Hysteresis and High Fracture Toughness for Flexible Electronics.

Stretchable materials, especially hydrogels, are emerging in various fields recently. Many applications demand low hysteresis and high fracture toughness of the materials to be used under dynamic mechanical loads. Herein, the authors report a hydrogel with high fracture toughness and low hysteresis through using a strong metal coordination bond and relatively high crosslinking density. This design allows the sacrificial bond to remain intact under normal operation, while fracturing to dissipate mechanical energy in the fracture zone to prevent propagation of the cracks. The obtained hydrogel exhibits a low hysteresis (≈1.5%) and a high fracture toughness (≈2,164 J m-2 ). Moreover, the hydrogel possesses a high fatigue threshold of ≈141 J m-2 and a reasonable conductivity. This study provides a worth-adopted approach to synthesize hydrogels with low hysteresis and high fracture toughness.

Effects of strong coordination bonds at the axial or equatorial positions on magnetic relaxation for pentagonal bipyramidal dysprosium(III) single-ion magnets.

Three pentagonal bipyramidal mononuclear Dy(III) complexes based on amino-substituted nitrophenol and tetradentate amide ligands of formulas [Dy(Hbpen)(OPhNO2NH2Cl)Cl2] (1), [Dy(Hbpen)(OPhNO2NH2)Cl2] (2) and [Dy(Hbpen)(OPhNO2NH2Cl)3] (3) (Hbpen = N,N'-bis(2-pyridylmethyl)-ethylenediamine, OPhNO2NH2Cl = 2-amino-6-chloro-4-nitrophenol, and OPhNO2NH2 = 2-amino-4-nitrophenol) were isolated. X-ray diffraction studies illustrate that complexes 1 and 2 with one strongly coordinating phenol ligand at their equatorial positions have a similar structure except for a slight difference in the chloride substituent of the phenol ligand. Complex 3 possesses the same equatorial coordination as 1 but its apical positions are occupied by two other phenol ligands. Magnetic studies show that 1 and 2 are zero-field single-ion magnets (SIMs), and 3 exhibits field-induced SIM behavior. Upon removing the chloride substituent groups from the phenol ligand, the effective energy barrier enhances from 233.7 K (1) to 362.7 K (2) under external dc fields. The stronger quantum tunneling of magnetization observed for 3 in comparison with 1 shows the destructive influence of a strong phenoxyl oxygen ligand field contributing to the transverse component on the magnetic properties. A comparison of complex 2 and the reported Dy(III) analogue [Dy(Hbpen)Cl(OPhBr2NO2)2] with two phenol ligands (2,6-dibromo-4-nitrophenol) in the axial direction leads to the conclusion that the magnetic anisotropy is strongly dependent on the Dy-Ophenoxyl bond lengths. The results provide direct information vital to understanding how the strong coordination environment at the axial or equatorial positions influences the SIM behavior.

Theoretical insight into the catalytic effect of transition metal ions on the aquathermal degradation of heavy oil: A DFT study of cyclohexyl phenyl amine cleavage

The recovery of oil deposits strongly depends on the flow characteristics. The degree of oil extraction can be substantially increased using the steam injection method, which can be further enhanced by catalytic upgrading of heavy oil fractions under conditions of aquathermolysis directly in the reservoir with the purpose to reduce viscosity. Transition metal ions, such as Fe(II), Co(II), Ni(II), and Cu(II), are capable of catalyzing the aquathermolysis reactions, but it is essential to better understand the mechanisms and kinetics of the catalytic aquathermolysis for effective selection and molecular design of catalysts for different types of heavy oil. In continuation of our previous theoretical efforts to clarify the catalytic mechanism and kinetics of the aquathermal cleavage of ether and sulfide heteroatomic linkages in heavy oil with use of quantum chemical tools, the thermochemical and kinetic parameters of catalytic aquathermolysis of cyclohexyl phenyl amine in the presence of transition metal ions are calculated by the DFT method based on the B3LYP, ωB97X-D, and M06-2X functionals. An analysis of the thermochemistry and kinetics of the aquathermolysis of model compound N-cyclohexyl aniline shows that the most probable mechanism of the aquathermal degradation proceeds through the heterolytic cleavage of the C–N bond with formation of cyclohexyl carbocation. According to the DFT calculation results, hydroxonium ions and transition metal ions, such as Fe(II), Co(II), and Ni(II), can substantially reduce the kinetic energy barrier of C–N bond breakage and, thereby, catalyze the aquathermal degradation of the model amine compound. However, the copper(II) ion stands out from other transition metals under study by stronger coordination bonds with amines, which leads to the self-poisoning of this catalyst by a reaction product, namely, aniline that is formed as a result of the aquathermolysis reaction. The catalytic effects of the hydroxonium ion and the iron(II), cobalt(II), and nickel(II) ions are comparable to each other and can be arranged in the following sequence in decreasing order of their catalytic strength: Ni2+ ≈ Co2+ > H3O+ > Fe2+.

A Zn(II) coordination polymer assembled by triazole derivative: Crystal structures and energetic behavior

It is a challenge to increase the oxygen content with maintaining the mechanical sensitivity of the energetic materials. In this work, the 1D solvent-free energetic coordination polymer [Zn3(μ3-OH)2(att)4]n1 (Hatt = 4-amino-1,2,4-triazole-5-thiol) was obtained in alkaline solution through a simple hydrothermal reaction. The X-ray crystallographic analysis indicates that there are two hydroxyl ions embedded in the three Zn(II) atoms through strong coordination bonds, which can provide a strategy for improving the oxygen content of energetic compounds. In addition, the energetic polymer 1 possesses high enthalpy of formation (2012.700 kJ·mol−1), low mechanical sensitivity (IS > 40 J, FS > 360 N) and relatively high decomposition temperature (235 °C). These results demonstrate that compound 1 has the potential application in insensitive energetic material.

New Energetic Metal‐Organic Framework (E‐MOF) based on a sodium(I)‐containing energetic metal salt incorporating guanidinium ions

AbstractSince there is an inherent contradiction between high‐detonation properties and reliable safety (or stability) with energetic materials, E‐MOFs provide an entirely new approach to balancing these properties. To explore the effects of the combination of MOFs with energetic materials and to elucidate their structure‐property relationships, we report herein the development of a novel guanidiniume (CH6N3+)‐containing E‐MOF based on the ligand di(2′H‐[1,5′‐bitetrazol]‐5‐yl)amine (C4H3N17), which was crystallized with a central sodium ion. The resulting [(CH6N3+)5(Na(I)‐(C4N173<M−>)2)]n solid featured a density of 1.625 g cm−3 and a decomposition temperature of 221 °C. The crystal structure of the complex featured a three‐dimensional layered structure with a significant number of hydrogen bonds between the layers. Moreover, the introduction of MOFs, provided a potential advantage over the dominant class of energetic materials, by boasting a multi‐dimensional structure with both non‐covalent interactions and covalent (coordination) bonds. As such, the introduction of shorter yet stronger coordination bonds in the E‐MOF led to a higher stability of the energetic material compared to only the weak (distant) intermolecular interactions of common explosives (i. e. hydrogen bonds).

Precise Construction of Stable Bimetallic Metal–Organic Frameworks with Single-Site Ti(IV) Incorporation in Nodes for Efficient Photocatalytic Oxygen Evolution

Precise Construction of Stable Bimetallic Metal–Organic Frameworks with Single-Site Ti(IV) Incorporation in Nodes for Efficient Photocatalytic Oxygen Evolution

Toughening polyisoprene rubber with sacrificial bonds: The interplay between molecular mobility, energy dissipation and strain-induced crystallization

Sacrificial bonds have been utilized to improve the mechanical properties of self-reinforced rubbers with strain-induced crystallization (SIC) behavior. However, the influence of sacrificial bonds on the SIC behavior under quasistatic and dynamic processes is rarely reported. Herein, weak hydrogen bonds and strong metal coordination bonds are introduced as sacrificial bonds to toughen polyisoprene rubber (IR). Compared with the sample containing only hydrogen bonds, the further introduction of coordination bonds form denser network and impose stronger restriction on the molecular mobility, leading to higher energy dissipation. The hydrogen bonds suppress the crystallization rate and crystallinity of SIC, due to the suppressed molecular mobility and orientation of amorphous chains. By contrast, the coordination bonds lead to smaller onset crystallization strain and partially recovered crystallinity, as they are difficult to relax during stretching and thus can maintain a higher degree of chain orientation. However, under dynamic cyclic loading, both the hydrogen and metal coordination bonds obviously retard the SIC and reduce the crystallinity after the first loading cycle, which is unfavorable for the dynamic mechanical properties. Despite this fact, the synergistic effect of SIC and energy dissipation significantly improves the quasistatic mechanical properties of the modified IR containing both hydrogen and metal coordination bonds.