Treatment activity of a mixed-ligand coordination polymer on gastric carcinoma

Reaction of 4,4′,4″-nitrilotribenzoic acid (H₃L), a C₃-symmetric ligand, with the divalent Co(II) salt Co(NO₃)₂·6H₂O in the present of the N-donor ligand 1,2-di(4-pyridyl)ethylene (DPE) affords a new mixed-ligand coordination polymer with the chemical formula of [Co₃(TNB)(DPE)₂]·2H₂O·DMF (1). In this study, CCK-8 assay was used to determine the effect of novel compound on proliferation of gastric cancer cells. The VEGF signaling pathway in gastric cancer cells was determined through employing real-time PCR after treatment of the above complex. Further, molecular docking simulation confirmed that the biological activity was coming from the carboxyl groups through the hydrogen bonding interactions with the receptor protein, the pyridine group only bonded with the Co ion for the formation of the Co complex.     

Controlled synthesis of ZnO nanoparticles from a Zn(II) coordination polymer: Structural characterization,optical properties and photocatalytic activity

A zinc coordination polymer derived from pyridine-2,6-dicarboxylate (PDC), {[Zn₂(PDC)₂]}_n, was successfully prepared via conventional, sonication and microwave-irradiation methods. The composition and characteristics of the obtained coordination polymers (CPs) were investigated by elemental analysis, TGA/DTA, X-ray diffraction and spectroscopic techniques. The so obtained CPs were heat-treated in the air at 600 °C for 2 h to produce ZnO of nanosized particles (NPs). It is of interest to note that the synthesis approach of the precursor greatly affects both the nanoparticle size and the structure of the resulting ZnO NPs. Moreover, the smallest particle size was associated with the sample derived from the ultrasonically prepared precursor. TEM analysis revealed that all samples have sphere-like morphologies. Structural analysis of the prepared ZnO samples was conducted and compared using Rietveld analysis of their PXRD patterns. Optical band gap calculations based on analysis of the UV–vis spectra of ZnO samples using Tauc's power law were achieved. The highest band gap of 3.63 eV was observed for ZnO sample obtained from the ultrasonically prepared precursor. Furthermore, the photocatalytic activity of ZnO NPs for the removal of Eosin Y color was monitored. The highest removal efficiency was recorded for ZnO originated from the ultrasonically synthesized precursor. Enhancement of removal efficiency that reached 98% was attained in only a period of 8 min. Its recycling test showed that it can be reused without structural changes over four cycling experiments.     

“Brown-Ring”-Related Coordination Polymers of the Quartet-{FeNO}7 Chromophore

A conspicuous detail of the so-called brown-ring test (the analytical test on nitrate) is the reddish color of the bottom layer of concentrated sulfuric acid, which develops upon the bleeding of the brown layer into the acid. Crystals of the same color form from a solution of ferrous sulfate in concentrated sulfuric acid on saturation with gaseous nitric oxide. The structure of this H₃O[{Fe(NO)(μ₄-SO₄)(μ₂-SO₄)_0.5}_n/n] ( 1a ) is made up from infinite chessboard-type layers with sulfur on the field junctions and Fe(NO) moieties below the black and above the white fields. An Fe–N–O angle of about 160° causes disorder in the tetragonal space group I4/mmm. A similar crystal pathology was found in the related [{Fe(MeOH)(NO)(μ₄-SO₄)}_n/n] ( 1b ) in the same crystal class. A one-dimensional coordination polymer is formed in crystals of a third compound that comprises the Fe(NO)O₅ coordination pattern, namely the brown oxalato species [{Fe(H₂O)(NO)(μ₂-ox)}_n/n · H₂O] ( 2 ). A still larger NO tilt of about 156° is not obscured by disorder in the triclinic crystals of 2 .     

Luminescent lanthanide coordination polymers with transformative energy transfer processes for physical and chemical sensing applications

The photophysical process of lanthanide(III) ion is based on the 4f-4f transition, which is the Laporte forbidden with narrow emission band and long emission lifetime. The 4f-4f emission process is affected by introducing aromatic organic ligands. In this review, recent progress of one-, two-, and three-dimensional polymer-typed lanthanide complexes, luminescent lanthanide coordination polymers, are focused for physical and chemical sensing applications. Their changeable luminescence depended on the physical and chemical environments come from the energy transfer between lanthanide(III) ions and aromatic organic ligands. The characteristic physical (temperature, pressure, pH and mechanical force) and chemical (adsorption of metal ions and molecules) sensitive luminescence of lanthanide coordination polymers are useful for future sensing applications.     

石墨烯负载的氧配位钴单原子稳定金属锂负极

Lithium (Li)-based batteries are the dominant energy source for consumer electronics, grid storage, and electrified transportation. However, the development of batteries based on graphite anodes is hindered by their limited energy density. With its ultrahigh theoretical capacity (3860 mAh∙g⁻¹), low redox potential (−3.04 V), and satisfactorily low density (0.54 g∙cm⁻³), Li metal is the most promising anode for next-generation high-energy-density batteries. Unfortunately, the limited cycling life and safety issues raised by dendrite growth, unstable solid electrolyte interphase, and "dead Li" have inhibited their practical use. An effective strategy is to develop a suitable lithiophilic matrix for regulating initial Li nucleation behavior and controlling subsequent Li growth. Herein, single-atom cobalt coordinated to oxygen sites on graphene (Co-O-G SA) is demonstrated as a Li plating substrate to efficiently regulate Li metal nucleation and growth. Owing to its dense and more uniform lithiophilic sites than single-atom cobalt coordinated to nitrogen sites on graphene (Co-N-G SA), high electronic conductivity, and high specific surface area (519 m²∙g⁻¹), Co-O-G SA could significantly reduce the local current density and promote the reversibility of Li plating and stripping. As a result, the Co-O-G SA based Li anodes exhibited a high Coulombic efficiency of 99.9% at a current density of 1 mA∙cm⁻² with a capacity of 1 mAh∙cm⁻², and excellent rate capability (high current density of 8 mA∙cm⁻²). Even at a high plating capacity of 6 mAh∙cm⁻², the Co-O-G SA electrode could stably cycle for an ultralong lifespan of 1300 h. In the symmetric battery, the Co-O-G SA based Li anode (Co-O-G SA/Li) possessed a stable voltage profile of 18 mV for 780 h at 1 mA∙cm⁻², and even at a high current density of 3 mA∙cm⁻², its overpotential maintained a small hysteresis of approximately 24 mV for > 550 h. Density functional theory calculations showed that the surface of Co-O-G SA had a stronger interaction with Li atoms with a larger binding energy, −3.1 eV, than that of Co-N-G SA (−2.5 eV), leading to a uniform distribution of metallic Li on the Co-O-G SA surface. More importantly, when matched with a sulfur cathode, the resulting Co-O-G SA/lithium sulfur full batteries exhibited a high capacity of 1002 mAh∙g⁻¹, improved kinetics with a small polarization of 191 mV, and an ultralow capacity decay rate of 0.036% per cycle for 1000 cycles at 0.5C (1C = 1675 mA∙g⁻¹) with a steady Coulombic efficiency of nearly 100%. Therefore, this work provides novel insights into the coordination environment of single atoms for the chemistry of Li metal anodes for high-energy-density batteries.     

Dinuclear manganese,iron, chromium,and cobalt complexes derived from aroylhydrazone ligands: Synthetic strategies,crystal structures,and magnetic properties

Coordination clusters of 3d metals continue to attract the intense interest of the scientists from the synthetic inorganic chemistry, bioinorganic chemistry and molecular magnetism communities. We review here the synthetic strategies employed in a continuous effort to obtain new and potentially magnetically interesting dinuclear molecules based on iron, manganese, chromium, and cobalt metal ions. The reported systems are pure homometallic 3d materials. We have focused on describing aspects of the synthesis, the crystal structures and the magnetic behaviour of these coordination compounds with low nuclearity. A deep solid-state and magnetic characterization of these systems has allowed us to gain evidence regarding the role played by weak exchange interactions and geometrical factors on the slow dynamics of the magnetization. In addition, the analysis through ab initio calculations has provided a valuable insight into the influence of organic periphery, bridging ligands, and remote substituents on the exchange coupling constant (J). In the case of a dinuclear complex based on manganese, the largest ferromagnetic interaction between two Mn^III has been observed (J = 19.7 cm⁻¹).     

Theoretical Investigation of the Mechanism of Rh(III)-catalyzed Annulation of 2-Biphenylboronic Acid with Activated Alkene

The mechanism is investigated for Cp^tBuRh(OH)₂-catalyzed annulation of 2-biphenylboronic acid with three activated alkenes using M06-2X functional. The reaction comprises transmetalation via two steps and following C-H activation producing reactive Rh-biphenyl complex with two Rh—C σ bonds. After the coordination/insertion of alkenes, respective fused or bridged cyclic products are yielded depending on different alkenes accompanied by the release of Cp^tBuRh. The promotion of Cp^tBuRh(OH)₂ lies in the barrier decrease of transmetalation and C-H activation ready for coordination/insertion ensuring the smooth progress of common rate-limiting reductive elimination. The stereoselective transfer and ring rotation are specific for benzoquinone and cyclopropenone. The role of Rh(III) catalyst and release of Rh(I) is supported by Multiwfn analysis on frontier molecular orbital(FMO) of specific transiton states(TSs) and Mayer bond order(MBO) value of vital bonding, breaking.     

Low Bandgap 2D Perovskite Single Crystal with Anomalous-large Charges/ions Collection Ratio for Ultra-sensitive and Stable X-ray Detectors

The low-dimensional halide perovskites have attracted increasing attention due to their improved moisture stability, reduced defects, and suppressed ions migration in many optoelectronic devices such as solar cells, light-emitting diodes, X-ray detectors, and so on. However, they are still limited by their large band gap and short charge carriers’ diffusion length. Here, we demonstrate that the introduction of metal ions into organic interlayers of two-dimensional (2D) perovskite by cross-linking the copper paddle-wheel cluster-based lead bromide ([Cu(O₂C−(CH₂)₃−NH₃)₂]PbBr₄) perovskite single crystals with coordination bonds can not only significantly reduce the perovskite band gap to 0.96 eV to boost the X-ray induced charge carriers, but can also selectively improve the charge carriers’ transport along the out-of-plane direction and blocking the ions motion paths. The [Cu(O₂C−(CH₂)₃−NH₃)₂]PbBr₄ single-crystal device can reach a record charges/ions collection ratio of 1.69×10¹⁸±4.7 % μGy_air⁻¹ s, and exhibit a large sensitivity of 1.14×10⁵±7% μC Gy_air⁻¹ cm⁻² with the lowest detectable dose rate of 56 nGy_air s⁻¹ under 120 keV X-rays irradiation. In addition, [Cu(O₂C−(CH₂)₃−NH₃)₂]PbBr₄ single-crystal detector exposed to the air without any encapsulation shows excellent X-ray imaging capability with long-term operational stability without any attenuation of 120 days.     

Introducing Bidirectional Axial Coordination into BiVO4@Metal Phthalocyanine Core–Shell Photoanodes for Efficient Water Oxidation

Core-shell photoanodes have shown great potential for photoelectrochemical (PEC) water oxidation. However, the construction of a high-quality interface between the core and shell, as well as a highly catalytic surface, remains a challenge. Herein, guided by computation, we present a BiVO₄ photoanode coated with ZnCoFe polyphthalocyanine using pyrazine as a coordination agent. The bidirectional axial coordination of pyrazine plays a dual role by facilitating intimate interfacial contact between BiVO₄ and ZnCoFe polyphthalocyanine, as well as regulating the electron density and spin configuration of metal sites in ZnCoFe phthalocyanine, thereby promoting the potential-limiting step of *OOH desorption. The resulting photoanode displayed a high photocurrent density of 5.7±0.1 mA cm⁻² at 1.23 V_RHE. This study introduces a new approach for constructing core–shell photoanodes, and uncovers the key role of pyrazine axial coordination in modulating the catalytic activity of metal phthalocyanine.     

A Dicyanomethyl Radical Conjugated with a Pyridylamino Group: Combining Radical-based Dynamic Covalent Chemistry and Coordination Chemistry

In this work, we aimed to develop a dicyanomethyl radical that undergoes both reversible C−C bond formation/dissociation and metal-ligand coordination reactions to combine dynamic covalent chemistry (DCC) based on organic radicals with coordination chemistry. We have previously reported a dicyanomethyl radical conjugated with a triphenylamine ( 1 ⋅) that exhibits a monomer/dimer equilibrium between the σ-bonded dimer ( 1₂ ). We designed and synthesized a novel dicyanomethyl radical with a pyridyl group as a coordination point ( 2 ⋅) by replacing the phenyl group of 1 ⋅ with a 3-pyridyl group. We showed that 2 ⋅ is also in an equilibrium with the σ-bonded dimer ( 2₂ ) in solution and has suitable thermodynamic parameters for application in DCC. 2₂ coordinates to PdCl₂ in a 2 : 2 ratio to selectively form a metallamacrocycle ( 2₂ )₂(PdCl₂)₂, and its structure was clarified by single crystal X-ray analysis. Variable-temperature NMR, ESR, and electronic absorption measurements revealed that ( 2₂ )₂(PdCl₂)₂ also undergoes the reversible C−C bond formation/dissociation reaction. Ligand-exchange experiment showed that 2₂ was liberated from ( 2₂ )₂(PdCl₂)₂ by the addition of another ligand with a higher affinity for Pd^II. This work demonstrated that DCC based on dicyanomethyl radicals works orthogonally to metal-ligand coordination reactions.