Metal Organic Coordination Compounds Research Articles

(C5H9NH3)2CuBr4 : A metal-organic two-ladder quantum magnet

Low-dimensional quantum magnets are a versatile materials platform for studying the emergent many-body physics and collective excitations that can arise even in systems with only short-range interactions. Understanding their low-temperature structure and spin Hamiltonian is key to explaining their magnetic properties, including unconventional quantum phases, phase transitions, and excited states. We study the metal-organic coordination compound (C5H9NH3)2CuBr4 and its deuterated counterpart, which upon its discovery was identified as a candidate two-leg quantum (S=12) spin ladder in the strong-leg coupling regime. By growing large single crystals and probing them with both bulk and microscopic techniques, we deduce that two previously unknown structural phase transitions take place between 136 and 113 K. The low-temperature structure has a monoclinic unit cell that gives rise to two inequivalent spin ladders. We further confirm the absence of long-range magnetic order down to 30 mK and investigate the implications of this two-ladder structure for the magnetic properties of (C5H9NH3)2CuBr4 by analyzing our own specific-heat and susceptibility data. Published by the American Physical Society 2024

Rapid charge extraction via hole transfer layer and interfacial coordination bonds on hematite photoanode for efficient photoelectrochemical water oxidation

Enhancing carrier separation and transport efficiency to achieve efficient water oxidation reaction is an important issue in photoelectrochemical (PEC) water splitting field, and introducing hole transfer layer (HTL) is an effective strategy to improve it. However, the difficulty of charge transfer between HTL and oxygen evolution catalyst (OEC) is a problem unresolved. To ameliorate the situation, we choose CoOOH as HTL and the metal–organic coordination compound constructed by 4,5-Imidazoledicarboxylic acid (IA) and Co/Ni ions as OEC. Using the interfacial coordination bonds as carrier transfer channels, the holes were rapidly extracted from HTL to OEC containing abundant active sites and participate in oxidation reaction. In consequence, the unique design results in a photocurrent density of 2.97 times that of α-Fe2O3 at 1.23 VRHE for the IACN/CoOOH/Fe2O3. This study reveals how the advisable design of photoanode promotes interfacial charge transfer and provides a valuable reference for the design of composite photoanode.

Influence of Co(II) and Cd(II) metal ions on structural, electronic and nonlinear optical properties of 4-methoxypyridine-2-carboxylic acid complexes: An experimental and computational study

Molecular engineering of metal-organic frameworks has attracted increasing attention due to their potential technological applications in the fields of optics and photonics. Therefore, a number of organometallic complexes are investigated for nonlinear optical applications. The current research aimed to synthesize and investigate spectroscopic and nonlinear optical properties of two metal-organic coordination compounds, namely Co(MeOPic)2∙(H2O)2 and Cd(MeOPic)2∙(H2O)2. The FT-IR and UV-Vis spectra for the distorted octahedral Co(II) and Cd(II) complexes were recorded. In order to provide a deep understanding about the relation between structure and nonlinear optical properties, density functional theory studies were also applied to both of the complexes by using B3LYP/6–311++G(d,p)/LanL2DZ level. TG-DTA analysis demonstrated that Cd(II) complex is approximately stable up to 134 °C, and the same complex only loss the aqua ligands between 134 and 189 °C. Therefore, the main skeleton part continues to remain stable up to 208 °C. Static NLO studies also demonstrated that both complexes have weak responses due to centrosymmetric structures, while Co(II) complex is appropriate to third-order NLO applications (γ (0;0,0,0) = 148.70×10−36 esu and γ (-2w;w,w,0)=-1521.4×10−36 esu).

Atomic Design of Copper Active Sites in Pristine Metal-Organic Coordination Compounds for Electrocatalytic Carbon Dioxide Reduction.

Electrocatalytic carbon dioxide reduction reaction (CO2RR) has emerged as a promising and sustainable approach to cut carbon emissions by converting greenhouse gas CO2 to value-added chemicals and fuels. Metal-organic coordination compounds, especially the copper (Cu)-based coordination compounds, which feature well-defined crystalline structures and designable metal active sites, have attracted much research attention in electrocatalytic CO2RR. Herein, the recent advances of electrochemical CO2RR on pristine Cu-based coordination compounds with different types of Cu active sites are reviewed. First, the general reaction pathways of electrocatalytic CO2RR on Cu-based coordination compounds are briefly introduced. Then the highly efficient conversion of CO2 on various kinds of Cu active sites (e.g., single-Cu site, dimeric-Cu site, multi-Cu site, and heterometallic site) is systematically discussed, along with the corresponding catalytic reaction mechanisms. Finally, some existing challenges and potential opportunities for this research direction are provided to guide the rational design of metal-organic coordination compounds for their practical application in electrochemical CO2RR.

Pyridine N-induced intra-pore and interfacial dual-confined Pd0-Pdδ+ synergistic catalysis for ultra-stable dehydrogenation of dodecahydro-N-propylcarbazole

We developed nano Pd catalysts, encapsulated within carbon-nitrogen layers at both intra-pore and interfacial levels on SiO2, via in-situ thermolysis of metal-organic coordination compounds. The catalysts dehydrogenation efficacy is greatly influenced by thermolysis temperature and ligand-to-metal ratio. The Pd-C-N2/SiO2-600 catalyst notably achieved complete dehydrogenation of 12 H-NPCZ within 240 minutes, demonstrating exceptional stability over 10 cycles without significant degradation, highlighting its viability for commercial use. Characterizations revealed that the C-N layer integration improves Pd nanoparticle dispersion and reduces strong acid site formation on catalyst surface. This synergy between the C-N layer and Pd nanoparticles promotes the formation and stabilization of Pdδ+ species, optimizing them as adsorption sites for dehydrogenation with appropriate acid strength. Moreover, this interaction adjusts the electronic states of Pd0 active sites, optimizing adsorption dynamics for intermediates. This cooperative action between Pd0 and Pdδ+ significantly boosts the desorption rate of dehydrogenation products, substantially improving the catalysis performance.

A Nickel-Based Coordination Compound with Tunable Morphology for High-Performance Anode and the Lithium Storage Mechanism

Metal-organic coordination compounds (MCCs) have received a lot of attention as anodes for lithium-ion batteries (LIBs) due to their abundant structural configuration, tunable morphology, high surface area, and low cost, but the lithium storage mechanism of MCCs is still a mystery. Herein, we synthesized a kind of nickel-based coordination compound (marked as Ni-PP-x, x = 1, 2, or 3) with tunable morphologies and different solvent ratios via a microwave irradiation solvothermal method and then applied them as anodes for LIBs. Among them, the Ni-PP-2 electrode, with a hollow and urchin-like structure, showed the longest lifespan and maintained a high capacity of 713 mAh g−1 at 2.0 A g−1 after 800 cycles. Measured by ex situ X-ray photoelectron spectroscopy (XPS) and ex situ Fourier transform infrared spectroscopy (FT-IR), the Ni-PP-2 electrode was confirmed by a redox reaction mechanism of Li+ cations with a benzene ring and O-Ni2+/O-Ni0 coordination bonds, and the cyclic voltammetry curves have exhibited a capacitive dominated lithium storage behavior. This work provides a new type of Ni-based coordination compound and an in-depth understanding of their lithium storage mechanism, paving the way for the application of MCC compounds in the future.

Polypyridine-based architectures for smart electrochromic and energy storage materials

The emerging role of metal–organic coordination compounds in the development of electrochromic materials (ECMs) fueled a growing interest in both the development of the new systems and their effective integration into functional devices. Coordination complexes of late transition metals with polypyridine ligands, like 2′-bipyridine (bpy) and 2,2′:6′,2″-terpyridine (tpy) often feature bright colours as a result of strong metal-to-ligand charge transfer. These colours could be reversibly bleached by oxidation of the metal centre and restored upon the metal centre reduction. The colour and its intensity can be controlled in different ways: by changing the nature of the metal centre(s) and by structural modification of ligand(s); by the construction of various metal–organic motifs and embedding them into devices, as well as by controlled layer-by-layer growth of the coordination assemblies on the surface of interest. The versatility of the available molecular building blocks allows for the systematic programming of the desired properties of the metal–organic units that could be effectively translated into the devices. This makes polypyridine metal complexes advantageous candidates for the design of effective ECMs. Here, we review the evolution of ECMs and devices based on molecularly defined bpy and tpy coordination adducts of late transition metals integrated into functional electrochromic devices over the past decade.

A kind of Co-based coordination compounds with tunable morphologies and its Li-storage mechanism

The metal-organic coordination compounds have shown great potential in lithium-ion batteries (LIBs) because of the moderate preparation conditions, high specific surface area, and diverse topological structures. Herein, a kind of Co-based coordination compounds with tunable morphologies are synthesized via a microwave-assisted solvothermal method by adjusting the molecular ratios between cobalt salts and phloroglucinol (PG) (Co-PG-x, x = 1, 2 and 3) for LIBs anode. Among them, Co-PG-2 with a unique flower structure, composed of ultra-thin flakes, has exhibited the most active sites (C=O, C=C groups of benzene ring and Co2+) and the highest specific surface areas. When applied as the anode of LIBs, Co-PG-2 has displayed excellent cycle stability (a high reversible capacity of 752 mAh g−1 at 1 A g−1 after 500 cycles) and an outstanding rate performance (up to 5 A g−1). Moreover, practical application is demonstrated by the full cells, composed of Co-PG-2 electrode and when paired with LiFePO4 in the full cells, it delivers a reversible capacity of 85 mAh g−1 at 0.2 A g−1 after 50 cycles. In a word, these Co-based coordination compounds have exhibited extraordinary prospects for renewable organic materials applied in lithium storage.

Sonochemical synthesis of the novel 1D zig-zag Hg(II)-Iodo bridged metal-organic coordination compounds with thiosemicarbazide derivative ligand

In the present research, a novel mercury (II) metal organic coordination compound, [Hg(Q)I2]n (Q = pyridine-4-carbaldehyde thiosemicarbazide) with nano rods shape was prepared applying an ultrasonic manner. The synthesized compound was determined with infrared spectroscopy (IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). In solid-state, the coordination polymer takes the appearance of a zig-zag 1D polymer. The coordination number of Hg (II) is four by one sulfur atom of organic ligand and three iodine atoms which two of iodine atoms are coordinated to other repeating units, and one of iodine is unattached. The zig-zag 1D chains interact with neighboring chains via weak interactions, making a 3D supramolecular metal organic polymer. It was found that using high-intensity ultrasound is a facile, versatile, and eco-friendly synthetic instrument for supramolecular coordination compounds. Also, types of non-covalent interactions in the structure cause extraordinary flexibility to perform secondary interactions and create the property of attracting guests to this host.

Low temperature heat capacity study of Co3(BTC)2·12H2O and Ni3(BTC)2·12H2O

Metal-organic coordination compounds have been extensively concerned in recent years due to their attracting chemical and physical properties. However, their thermodynamic properties have not been well investigated compared with the other properties, which would limit understanding their relationship between molecular structure and functional performance from a basic thermodynamic view. In the present work, two crystalline compounds of Co3(BTC)2·12H2O (1) and Ni3(BTC)2·12H2O (2) (BTC = 1,3,5- benzenetricarboxylate) have been designed and synthesized using a solvothermal method. The variable-temperature magnetic susceptibilities of these two compounds have been measured and the results revealed that compounds 1 and 2 possessed antiferromagnetic interaction between CoII/NiII ions. Low temperature heat capacities of these two compounds have been measured using a heat capacity option of Physical Property Measurement System in the temperature range from (1.9 to 300) K, and a Schottky effect has been revealed in the heat capacity curve below 10 K. The experimental heat capacity data have been fitted to a series of theoretical and empirical heat capacity models, and the corresponding thermodynamic functions such as enthalpy and entropy have been calculated in the temperature range from (0–300) K based on these models and fitting parameters. Also, the entire Schottky effect peak has been well presented in the heat capacity curve using these fitted heat capacities. The thermodynamic properties obtained in this work may provide significant thermodynamic basis for further investigating the related functional properties of these two compounds.

Anion-directed assemblies of Cu(II) mono, di, and poly-nuclear coordination compounds with a 32-membered azacrown ligand: Synthesis, characterisation and crystal structures

A novel 32-membered azacrown ligand L was synthesized from the [2 + 2] condensation between 2-[3-(2-formylphenoxy)-2-hydroxy propoxy]benzaldehyde and 1,2-diaminopropane by following in situ reduction. Three metal-organic coordination compounds [CuL(NCS)]NO3·CH3OH (1), [Cu2L(CH3COO)4].0.5H2O (2), and [CuL(μ-Cl)(NO3)]n.2nCH3CN (3), were prepared from reaction of L with copper(II) salts containing different anions. Depending on the reaction controlling factor, i.e. NCS−, CH3COO−, NO3−, and Cl− anions, mono, di and polynuclear metal-organic coordination compounds were constructed. Complexes were characterized by spectroscopic methods and single crystal X-ray diffraction. Crystal structures indicate that L in presence of NCS− and Cu(NO3)2·3H2O forms mononuclear complex 1. Dinuclear complex 2 was formed by the reaction of L in presence of Cu(CH3COO)2·2H2O. Reaction of Cu(NO3)2·3H2O and CuCl2·3H2O with L give rise complex 3 which is a 1-dimensional coordination polymer. The coordination polymer constructed from distorted octahedron shaped copper nucleus that are exomacrocylic in which two Cl atoms serve as bridge. Potentially decadentate ligand, L, with four N- and six O-donor sites in presence of Cu(II) salts reacts only with its N-donors. Complexes 1 and 3, both, are crystalized in a centrosymmetric space group P21/c and dinuclear complex 2 is crystalized in a polar space group P21.

Two novel Zn(II)-Li(I)-based and In(III)-based coordination polymers: crystal structures and anti-lung cancer activity

Abstract In this study, two new metal-organic frameworks, namely, {(H2NMe2)[Zn3LiO(BTA)2](DMF)3}n (1, H3BTA=3,3′,3″-[1,3,5-benzenetriyltris(carbonylimino)] trisbenzoic acid) and {(Me2NH2)2[In2(TTA)2(FBA)2](DMF)3}n (2, H3TTA=4,4′-(((5-((4-(hydroxy-l2-methoxy)phenoxy) methyl)-2,4,6-trimethyl-1,3-phenylene)bis(methylene))bis(oxy))dibenzoic acid, HFBA=2-fluorobenzoic acid), were obtained via a one-pot solvothermal reaction of metal salts and organic connectors. The structures of the title two metal-organic coordination compounds were structurally probed via X-ray single crystal diffraction technique. In connection to their structures, the MTT assay was used to access the in vitro antitumor activities for compounds 1 and 2 against the human lung cancer cells (MSTO-211H, NCI-H1299 and NCI-H292).

Low-temperature synthesis of NiS/MoS2/C nanowires/nanoflakes as electrocatalyst for hydrogen evolution reaction in alkaline medium via calcining/sulfurizing metal-organic frameworks

Based on four precursors of metal-organic frameworks (MOFs) or coordination compounds with different Ni/Mo ratios (1:1, 1:4 or only Mo involved), four electrocatalysts with different NiS/MoS2 molar ratios have been obtained via low temperature calcining and sulfurizing technique. Among the four precursors, MOF 2/AC precursor exhibits a regular morphology of 3D bunched nanorods due to the addition of the hard template of activated carbon (AC) during the synthesis of MOF 2. As a result, the calcined product, S2/AC (NiS/MoS2 = 1: 4) exhibits a morphology of the hierarchical nanorods built by MoS2/C nanowires and NiS/MoS2 nanoflakes, and it shows the best hydrogen evolution reaction activity in alkaline electrolyte among the four electrocatalysts with an overpotential of 117 mV at 10 mA cm−2, a small Tafel slope of 58 mV and excellent electrochemical durability, which was probably attributed to the excellent conductivity, abundant exposed active sites and synergistic effect of the different components in the sample. Moreover, S2/AC exhibited an improved electrocatalytic activity for hydrogen evolution reaction (HER) after stability test with a decreased overpotential (98 mV) at 10 mA cm−2, which was probably due to the improved morphology of the sample with more dispersed nanowires and nanoflakes after the stability test, leading to more NiS active sites exposed to the electrolyte. The detailed mechanism is under investigation.

Electronic and Structural Effects of Inner Sphere Coordination of Chloride to a Homoleptic Copper(II) Diimine Complex

The reaction of CuCl2 with 2,9-dimethyl-1,10-phenanthroline (dmp) does not lead to the formation of [Cu(dmp)2](Cl)2 but instead to [Cu(dmp)2Cl]Cl, a 5-coordinated complex, in which one chloride is directly coordinated to the metal center. Attempts at removing the coordinated chloride by changing the counterion by metathesis were unsuccessful and resulted only in the exchange of the noncoordinated chloride, as confirmed from a crystal structure analysis. Complex [Cu(dmp)2Cl]PF6 exhibits a reversible cyclic voltammogram characterized by a significant peak splitting between the reductive and oxidative waves (0.85 and 0.60 V vs NHE, respectively), with a half-wave potential E1/2 = 0.73 V vs NHE. When reduced electrochemically, the complex does not convert into [Cu(dmp)2]+, as one may expect. Instead, [Cu(dmp)2]+ is isolated as a product when the reduction of [Cu(dmp)2Cl]PF6 is performed with l-ascorbic acid, as confirmed by electrochemistry, NMR spectroscopy, and diffractometry. [Cu(dmp)2]2+ complexes can be synthesized starting from Cu(II) salts with weakly and noncoordinating counterions, such as perchlorate. Growth of [Cu(dmp)2](ClO4)2 crystals in acetonitrile results in a 5-coordinated complex, [Cu(dmp)2(CH3CN)](ClO4)2, in which a solvent molecule is coordinated to the metal center. However, solvent coordination is associated with a dynamic decoordination-coordination behavior upon reduction and oxidation. Hence, the cyclic voltammogram of [Cu(dmp)2(CH3CN)]2+ is identical to the one of [Cu(dmp)2]+, if the measurements are performed in acetonitrile. The current results show that halide ions in precursors to Cu(II) metal-organic coordination compound synthesis, and most likely also other multivalent coordination centers, are not readily exchanged when exposed to presumed strongly binding and chelating ligand, and thus special care needs to be taken with respect to product characterization.

Syntheses and single crystal X-ray diffraction analysis of five isostructural 2D MOCCs

Five two-dimensional metal–organic coordination compounds (MOCCs) have been solvothermally synthesized by the combination of 2-aminonicotinic acid (ANA) and transition metal ions, viz. Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), in water–ethanol mixed solvent. They are formulated as [Co(C6H5N2O2)2], (Co–ANA); [Ni(C6H5N2O2)2], (Ni–ANA) [Cu(C6H5N2O2)2], (Cu–ANA), [Zn(C6H5N2O2)2], (Zn–ANA) and [Cd(C6H5N2O2)2], (Cd–ANA). Single crystal X-ray diffraction studies for the complexes Co–ANA, Ni–ANA and Cd–ANA have also been carried out. These three complexes crystallize in the tetragonal crystal system with the space group P41212. The metal ions in all these complexes have an octahedral coordination environment. The six coordinations are satisfied by two pyridine N-atoms from two different ANA ligands and four oxygen atoms from two chelating carboxylate groups of another two ANA ligands. The topological motif of the coordination network is defined as 2-periodic net or square lattice (sql). These complexes were further characterized by elemental, FT-IR spectral, thermal and powder X-ray diffraction analyses.

Synthesis and Characterization of Non-Linear Optical Crystal of Manganese Mercury Thiocyanate Glycol Monomethyl Ether

The design and synthesis of organic nonlinear optical (NLO) crystals are a promising area of current research in materials science. Organic materials are found to possess better non linear optical properties when compared to inorganic materials. Recently, there has been a widespread interest in the metal-organic coordination compounds, which are a combination of metal and organic ligands, having exciting NLO properties. Non-linear optical single crystals of Manganese mercury thiocyanate glycol monomethyl ether (MMTG) were grown from a mixed solvent of glycol monomethyl ether and water by slow evaporation method. Optimum conditions for the growth at ambient temperature were found by investigating different growth parameters. The percentage of optical transmittance by the grown crystal was ascertained by a UV-visible spectral study. The growth features of MMTG crystal was observed by Field Emission Scanning Electron Microscopy technique and Epifluorescence studies for the same were carried out for the first time thus revealing the excitation of the sample around 545 nm. Dielectric measurements on MMTG single crystal were carried out for various frequencies at different temperatures.

Chelation Competition Induced Polymerization (CCIP): A Binding Energy Based Strategy for Nonspherical Polymer Nanocontainers’ Fabrication

Polymer based nanocontainers have attracted a myriad of interests due to their functional groups, mechanical stability, combining with inner voids and large specific surface area. Preparation of polymer nanocontainers with specific nonspherical geometric morphology, precisely controllable structure, composition, and functionalities still remains a significant challenge. Here, we report a method that enables synthesizing nonspherical polymer nanocontainers with different morphologies and properties by using anisotropic metal–organic coordination compounds as templates. The preparation process is based on the stronger monomer’s binding ability to metal cations than that to the organic linkers. The correlation between the binding energy and the formation of the hollow structure is calculated theoretically. Polymer nanocontainers with multiple morphologies (such as octahedron, dodecahedron, etc.) are constructed by expanding template materials. The as-prepared polymer nanocontainers exhibit active properties ...

A Nano Nickel (II) Metal–Organic Coordination Compound for Nano Nickel (II) Oxide: Sonochemical Synthesis and Characterization

A sonochemical method was used to synthesize a nickel (II) coordination complex, [Ni(phen)3](BF4)2·H2O}n (1) (phen = 1,10-phenamthroline), with particle sizes in the range of 40–120 nm. The new nanostructure was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (PXRD), infrared, and elemental analyses. Compound 1 was structurally characterized by single-crystal X-ray diffraction, and the data show that the Ni(II) ions are coordinated by six N-donor atoms from three phen ligands. The charge was balanced by two tetrafluoroborate anions. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. They are further extended into a three-dimensional (3-D) supramolecular structure by weak π–π directional intermolecular interactions. Cubic NiO nanoparticles with sizes of 5–40 nm were obtained by thermolysis of 1 at 180 °C.

Anion-Mediated Architecture and Photochromism of Rigid Bipyridinium-Based Coordination Polymers

Four metal–organic coordination compounds Zn2(bcbp)Cl4 (1), Zn(bcbp)(PO3F) (2), [CdCl(Hbcbp)(bcbp)]·(ClO4)2 (3), and [Cd2(bcbp)4]·(ClO4)·F3 (4) (H2bcbp·2PF6 = 1,1′-bis(4-carboxyphenyl)-(4,4′-bipyridinium) hexafluorophosphate) have been synthesized via a solvothermal method and structurally characterized. Compound 1 is a 1D coordination polymer, while compound 2 shows a 2D + 2D → 3D inclined polycatenation structure. In the case of compound 3, due to the capped chlorine atoms and uncoordinated carboxyl of bcbp ligand, it exhibits a 1D T-shaped coordination configuration. Compound 4 is an unprecedented 13-fold interpenetrating structure with huge diamondoid frameworks. Because of the presence of electron-deficient bipyridinium moieties, the photochromic behaviors of these compounds have also been studied. Interestingly, only compounds 1–3 exhibit color changes under light irradiation. The impact of these anions on the photochromic process is discussed.

Syntheses, Structures, Thermal Stability, and Photophysical Properties of a Cadmium Compound With Mixed Ligands

A novel metal-organic coordination compound [Cd(mip)(GTC)]n (1) [mip = 2-(3-methoxyphenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, GTC = pentanedioic acid] has been synthesized by hydrothermal reactions and characterized by elemental analysis, thermogravimetric (TG) analysis, infrared spectrum (IR), and single-crystal X-ray diffraction. Single-crystal X-ray diffraction reveals that 1 exhibits two-dimensional (2D) layer architecture, and the H-bond intersections link the 2D layer architecture to 3D structure. TG analysis shows clear courses of weight loss, which corresponds to the decomposition of different ligands. We also study the luminescent properties for the ligand and compound 1, and the results suggest that title compound is very thermal stable and worthy of further study as candidate of potential photoluminescence material.