Class Of Coordination Compounds Research Articles

Evolution of Cu-Co-Fe Prussian Blue Analogues with Open Nanoframe Architectures for Enhanced Electrochemical Capacitive Deionization

Water scarcity is one of the most severe global challenges in our generation. Electrochemical capacitive deionization (CDI), a green water desalination system, has emerged as a promising technology for producing clean water due to its low energy consumption and environmentally friendly. Prussian blue analogues (PBAs), a class of coordination compounds which can accommodate Na+ ions into their nanoscale interspaces of skeleton frameworks, promise their extraordinary functionalities in CDI technology. Volume expansion that occurs during the ion-insertion/extraction process and inherent low conductivity of PBA electrodes, however, still inevitably lead to their sluggish desalination kinetics and capacity fading. Herein, preparation of trimetallic PBA containing copper, cobalt, and iron with nanoframe superstructures (CuCoFe-PBA NFs) via a multi-step in-situ structural conversion is reported. Comparable experiments indicate that successful conversion via this route is attributable to a self-templated epitaxial growth triggered by the additional introduction of Cu ions into the reaction system. The optimal composition and three-dimensional (3D) opened nanoframe structure of CuCoFe-PBA NFs offer the electrode with rich redox active species, abundant accessible adsorption sites, and fast ion transport that enhance its capacitive deionization (CDI) performance. As a result, the CuCoFe-PBA NFs demonstrate an exceptional CDI performance with a desalination capacity of 46.8 mg g-1 at an applied potential of 1.4 V and superior cyclability with negligible decay on the desalination capacity even after 100 cycle tests. Figure 1

Synthesis, Structure and Biological Activity of Indole-Imidazole Complexes with ZnCl2: Can Coordination Enhance the Functionality of Bioactive Ligands?

The ability of the indole-imidazole hybrid ligands to coordinate with the Zn(II) ion and the resulting structures of this new class of coordination compounds were analyzed in order to determine their structural properties and biological functionalities. For this purpose, six novel Zn(II) complexes, [Zn(InIm)2Cl2] (1), [Zn(InMeIm)2Cl2] (2), [Zn(IniPrIm)2Cl2] (3), [Zn(InEtMeIm)2Cl2] (4), [Zn(InPhIm)2Cl2] (5) and [Zn2(InBzIm)2Cl2] (6) (where InIm is 3-((1H-imidazol-1-yl)methyl)-1H-indole), were synthesized by the reactions of ZnCl2 and the corresponding ligand in a 1:2 molar ratio in methanol solvent at an ambient temperature. The structural and spectral characterization of these complexes was performed using NMR, FT-IR and ESI-MS spectrometry and elemental analysis, and the crystal structures of 1-5 were determined using single-crystal X-ray diffraction. Complexes 1-5 form polar supramolecular aggregates by utilizing, for this purpose, the N-H(indole)∙∙∙Cl(chloride) intermolecular hydrogen bonds. The assemblies thus formed differ depending on the distinctive molecular shape, which can be either compact or extended. All complexes were screened for their hemolytic, cytoprotective, antifungal, and antibacterial activities. The results show that the cytoprotective activity of the indole/imidazole ligand significantly increases upon its complexation with ZnCl2 up to a value comparable with the standard antioxidant Trolox, while the response of its substituted analogues is diverse and less pronounced.

A Comprehensive Review of Organotin Complexes: Synthesis and Diverse Applications

Organotin complexes are a class of coordination compounds that contain tin as a central metal atom bonded to organic ligands. These complexes have been extensively studied for their synthetic versatility and wide range of applications in various fields. Here is a review of organotin complexes, including their synthetic methods and applications.

The Emerging Role of Cyclodextrin Metal–Organic Frameworks in Ostheotherapeutics

Metal–Organic Frameworks (MOFs) are a class of coordination compounds with high versatility of design and a high loading ability. These properties have made them increasingly attractive for drug delivery, with research focusing mostly on the preparation of biocompatible MOFs. A suitable strategy is the use of cyclodextrins, cyclic oligosaccharides with excellent biosafety profiles. This review summarises the early steps taken in the application of cyclodextrin-coated and cyclodextrin-based MOFs in the treatment of bone-related diseases divided into three categories: cyclodextrin-coated MOFs, cyclodextrin-based MOFs and cross-linked derivatives of CD-MOFs. Applications in the delivery of bisphosphonates, osteoporotic regulating drugs and non-steroidal anti-inflammatory drugs, for osteoarthritis management, are highlighted. Lastly, the use of these materials in dentistry is exemplified with a recent report.

Crystallographic and theoretical study of the atypical distorted octahedral geometry of the metal chromophore of zinc(II) bis((1R,2R)-1,2-diaminocyclohexane) dinitrate

The topic of the study is crystallographic experimental and theoretical electron density analyses of entitled complex zinc(II) bis((1R,2R)-1,2-diaminocyclohexane) dinitrate (1), showing an atypical of ZnII-ion octahedral geometry of the metal chromophore (ZnO2N4.) The ligand 1,2-diaminocyclohexane (L) is characterized by a diversity of coordination modes with transition metal ions. Also, it has been broadly used to design of new metal-organic anticancer medications, for instance, looking at its PtII-complex (oxaliplatin) at clinical trials. Its coordination capability of ZnII-ion reveals mainly complexes with a distorted Td* geometry of the metal chromophore, including cases of complexes of simply N-substituted derivatives of the ligand. These empirical arguments arise a very important question: What are the governing molecular and environmental factors causing for the observed geometry of the chromophore in complex (1)? In order to address this question, we shed light on correlation among molecular structure ⇔ electronic structure ⇔ nature of metal-to-ligand bond (ML) ⇔ energetics of ML bond ⇔ thermodynamics of ZnII–metal organics of 1,2-diaminocyclohexane. A comparative analysis between octahedral complex (1) and classical tetrahedral coordination compounds of ZnII–ion with 1,2-diaminocyclohexane and ethylenediamine (en) is carried out. High resolution crystallographic data are used. Static and molecular dynamics ab initio methods and those based on density functional theory are employed. The methods of atoms in molecules (AIM) and natural bond orbital (NBO) are utilized, as well.

Resolvable polymorphism in an intergrowth of two modifications of tris(diethyldithiocarbamato)antimony.

Tris(diethyldithiocarbamato-κS)antimony(III), [Sb(C5H10NS2)3], is tentatively presumed to comprise a triclinic and a monoclinic polymorph intergrown into each other. The geometry in the triclinic phase is a ψ-capped octahedron and that in the monoclinic phase is a ψ-pentagonal bipyramid. The study also identifies the polyhedral symbols for a reported pair of polymorphs of another SbIII coordination compound, as well as for those of published polymorphic modifications of other BiIII and PbII coordination compounds; the symbols in the pair differ in most of these examples. When differentiating related structures of such classes of coordination compounds, lone-pair stereochemistry may be another informative variable, as stereochemical activity is not always apparent from bond distances and angles only.

Spin Transition in the Cobalt(II) Clathrochelate Films From Electron Spectroscopy Data

The spin states of three earlier described cobalt(II) clathrochelates as films on the quartz supports are studied for the first time. The magnetochemical study shows that the temperature-induced spin transition observed previously in the crystalline samples is retained in the films, which makes it possible to consider this class of coordination compounds with high chemical and thermal stability as promising components for molecular spintronic devices.

Structural and Chemical Transformations of Ruthenium, Cobalt, and Iron Clathrochelates Used as Electrocatalysts for a Hydrogen Evolution Reaction in a Water Electrolyzer

The structural evolution of three electrocatalytic systems for hydrogen evolution reaction using iron, cobalt, and ruthenium(II) clathrochelate complexes as catalysts in a water electrolyzer is studied by X-ray absorption near-edge structure (XANES)/extended X-ray absorption fine structure (EXAFS) spectroscopy. The complexes are shown to display essentially different robustness under water electrolysis conditions in pilot-scale hydrogen generators. The iron and cobalt(II) clathrochelates preserve their cage, macrobicyclic structure, and the encapsulated metal(II) ion is reduced to metal(I) cation; whereas in the case of ruthenium(II) clathrochelate, the cage complex undergoes partial decomposition to form sulfur-containing products of decomposition of the encapsulating macrobicyclic hexasulfide ligand, which results in the accumulation of the ruthenium disulfide RuS2 in used clathrochelate-containing cathode material. Taking into account our experimental data on the chemical transformation of clathrochelate electrocatalysts under the conditions of 2Н+/Н2 reaction, we discuss the possibilities for boosting the efficiency of electrocatalytic systems based on this class of coordination compounds.

Photophysics and Photochemistry of Iron Carbene Complexes for Solar Energy Conversion and Photocatalysis

Earth-abundant first row transition metal complexes are important for the development of large-scale photocatalytic and solar energy conversion applications. Coordination compounds based on iron are especially interesting, as iron is the most common transition metal element in the Earth’s crust. Unfortunately, iron-polypyridyl and related traditional iron-based complexes generally suffer from poor excited state properties, including short excited-state lifetimes, that make them unsuitable for most light-driven applications. Iron carbene complexes have emerged in the last decade as a new class of coordination compounds with significantly improved photophysical and photochemical properties, that make them attractive candidates for a range of light-driven applications. Specific aspects of the photophysics and photochemistry of these iron carbenes discussed here include long-lived excited state lifetimes of charge transfer excited states, capabilities to act as photosensitizers in solar energy conversion applications like dye-sensitized solar cells, as well as recent demonstrations of promising progress towards driving photoredox and photocatalytic processes. Complementary advances towards photofunctional systems with both Fe(II) complexes featuring metal-to-ligand charge transfer excited states, and Fe(III) complexes displaying ligand-to-metal charge transfer excited states are discussed. Finally, we outline emerging opportunities to utilize the improved photochemical properties of iron carbenes and related complexes for photovoltaic, photoelectrochemical and photocatalytic applications.

A new heteroleptic phosphorescent cuprous complex supported by a BINAP ligand: synthesis, structure, luminescence properties and theoretical analyses

Luminescent cuprous complexes are an important class of coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The heteroleptic cuprous complex solvate rac-(acetonitrile-κN)(3-aminopyridine-κN)[2,2'-bis(diphenylphosphanyl)-1,1'-binaphthyl-κ2P,P']copper(I) hexafluoridophosphate dichloromethane monosolvate, [Cu(C5H6N2)(C2H3N)(C44H32P2)]PF6·CH2Cl2, conventionally abbreviated as [Cu(3-PyNH2)(CH3CN)(BINAP)]PF6·CH2Cl2, (I), where BINAP and 3-PyNH2 represent 2,2'-bis(diphenylphosphanyl)-1,1'-binaphthyl and 3-aminopyridine, respectively, is described. In this complex solvate, the asymmetric unit consists of a cocrystallized dichloromethane molecule, a hexafluoridophosphate anion and a complete racemic heteroleptic cuprous complex cation in which the cuprous centre, in a tetrahedral CuP2N2 coordination, is coordinated by two P atoms from the BINAP ligand, one N atom from the 3-PyNH2 ligand and another N atom from a coordinated acetonitrile molecule. The UV-Vis absorption and photoluminescence properties of this heteroleptic cuprous complex have been studied on polycrystalline powder samples, which had been verified by powder X-ray diffraction before recording the spectra. Time-dependent density functional theory (TD-DFT) calculations and a wavefunction analysis reveal that the orange-yellow phosphorescence emission should originate from intra-ligand (BINAP) charge transfer mixed with a little of the metal-to-ligand charge transfer 3(IL+ML)CT excited state.

Boron Dipirrins: Mechanism of Formation, Spectral and Photophysical Properties, and Directions of Functionalization

Boron dipyrrins (Bodipy) are unique complexes occupying an intermediate position between classical coordination and organometallic compounds. The enormous interest of researchers from all over the world to the compounds of this class has by now provided an endless stream of publications that requires generalization. Existing reviews and original publications do not fully cover the structural diversity of Bodipy and their possible applications in engineering, medicine, analytical chemistry, optics, photonics, etc. In this paper, w e present the results, mainly of our own research, which for the first time allowed us to establish the physicochemical principles of the formation of Bodipy (the reasons for the low rates of complexation of ligands with boron trifluoride), changes in the spectral and photophysical properties of alkylated Bodipy complexes with the separation of contributions from universal and specific solvation, and examples of functionalization of inorganic and organic polymer materials based on Bodipy of different structures. Examples of the current team’s Bodipy research in different practical areas are presented.

Brice Bosnich. 3 June 1936—13 April 2015

Brice Bosnich, an Australian inorganic chemist, graduated from the University of Sydney and obtained his PhD at the Australian National University, Canberra. He then worked successively at University College London, the University of Toronto and the University of Chicago. He had an abiding interest in stereochemistry and its relationship with chemical reactivity, and in the chirality and optical activity of coordination and organometallic complexes, mainly those of the d-block elements. His early studies concerned the topological and conformational behaviour of classical coordination compounds, mainly of cobalt(III), and made extensive use of the technique of circular dichroism. He put this background to elegant use in perhaps his most distinctive work, namely, the design and synthesis of a C 2 -symmetric ditertiary phosphine, ( S , S )-chiraphos, the rhodium(I) complex [Rh{Ph 2 PCH(CH 3 )CH(CH 3 )PPh 2 }] + of which catalysed efficiently the homogeneous hydrogenation of prochiral enamides to amino acids in high optical purity. Bosnich traced the high enantioselectivity to the chiral array of P-phenyl substituents that is generated on coordination of ( S , S )-chiraphos. In principle, catalytic enantioselective synthesis represents a powerful and economic method of introducing chirality into the synthesis of biologically active molecules, which, since the thalidomide tragedy, are required to be marketed only in optically pure forms. Dissymmetric ligands similar to ( S , S )-chiraphos are now routinely employed in this type of synthesis. Bosnich developed several other enantioselective processes based on organo-transition metal chemistry. He also had several quasi-theoretical interests, including the possible use of circular dichroism to determine the absolute configuration of chiral metal complexes, and the development of a molecular mechanics force field for metallocenes. He maintained a strong interest in the properties of multimetallic proteins and devoted much effort to the construction of chiral binucleating ligands. During the 7–8 years before his retirement from the University of Chicago in 2006, he shifted his research to supramolecular recognition by suitably designed metal complexes.

On the Aggregation and Sensing Properties of Zinc(II) Schiff-Base Complexes of Salen-Type Ligands.

The zinc(II) ion forms stable complexes with a wide variety of ligands, but those related to Schiff-bases are among the most largely investigated. This review deals with the peculiar aggregation characteristics of Zn(II) Schiff-base complexes from tetradentate N2O2 salen-type ligands, L, derivatives from salicylaldehydes and 1,2-diamines, and is mostly focused on their spectroscopic properties in solution. Thanks to their Lewis acidic character, ZnL complexes show interesting structural, nanostructural, and aggregation/deaggregation properties in relation to the absence/presence of a Lewis base. Deaggregation of these complexes is accompanied by relevant changes of their spectroscopic properties that can appropriately be exploited for sensing Lewis bases. Thus, ZnL complexes have been investigated as chromogenic and fluorogenic chemosensors of charged and neutral Lewis bases, including cell imaging, and have shown to be selective and sensitive to the Lewis basicity of the involved species. From these studies emerges that these popular, Lewis acidic bis(salicylaldiminato)Zn(II) Schiff-base complexes represent classical coordination compounds for modern applications.

A novel luminescent ionic trinuclear Cu3I2 cluster cuprous complex supported by a P^N ligand: synthesis, structure characterization, properties and TD-DFT calculations.

Luminescent cuprous complexes are an important class of coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The title ionic trinuclear Cu3I2 complex, tris[μ2-diphenyl(pyridin-2-yl)phosphane-κ2P:N]di-μ3-iodido-tricopper(I)(3 Cu-Cu) hexafluoridophosphate, [Cu3I2(C39H32NP)3]PF6, conventionally abbreviated as [Cu3I2(Ph2PPy)3]PF6, is described. Each CuI atom is coordinated by two μ3-iodide ligands and by a P and an N atom from two Ph2PPy ligands, giving rise to a CuI2PN tetrahedral coordination geometry about each CuI centre. The electronic absorption and photoluminescence properties of this trinuclear cluster have been studied on as-synthesized samples, which had been examined previously by powder X-ray diffraction. A detailed time-dependent density functional theory (TD-DFT) study was carried out and showed a green emission derived from a halide-to-ligand charge transfer and metal-to-ligand charge transfer 3(X+M)LCT excited state.

N‐Heterocyclic Phosphenium Dihalido‐Aurates: On the Borderline between Classical Coordination Compounds and Ion Pairs

2‐Bromo‐ and 2‐chloro‐1,3,2‐diazaphospholenes react with (tht)AuCl to afford isolable N‐heterocyclic phosphenium (NHP) dihalido‐aurates, which were characterized by analytical and spectroscopic data and in one case by a single‐crystal X‐ray diffraction study. The T‐shaped metal coordination sphere found in the crystal consists of a pseudo‐linear AuX2 unit that is perturbed by a weakly bound NHP unit. DFT studies indicate that the subunits interact mainly through electrostatic and dispersion forces, with negligible covalent contributions, and that the phosphenium dibromido‐aurate is slightly more stable than an isomeric complex with an intact bromophosphane ligand. NMR studies reveal that the NHP‐AuX2 pairs persist in solution but are kinetically labile and readily undergo halide scrambling. The hydride/fluoride exchange reaction between a secondary phosphane‐AuCl complex and [Ph3C][BF4] implies that a gold complex with an intact 2‐halogeno‐1,3,2‐diazaphospholene ligand may be more stable than its phosphenium dihalido‐aurate isomer when covalent P–X bonding contributions are strengthened.

A Stable Pentagonal Bipyramidal Dy(III) Single-Ion Magnet with a Record Magnetization Reversal Barrier over 1000 K.

Single-molecule magnets (SMMs) with a large spin reversal barrier have been recognized to exhibit slow magnetic relaxation that can lead to a magnetic hysteresis loop. Synthesis of highly stable SMMs with both large energy barriers and significantly slow relaxation times is challenging. Here, we report two highly stable and neutral Dy(III) classical coordination compounds with pentagonal bipyramidal local geometry that exhibit SMM behavior. Weak intermolecular interactions in the undiluted single crystals are first observed for mononuclear lanthanide SMMs by micro-SQUID measurements. The investigation of magnetic relaxation reveals the thermally activated quantum tunneling of magnetization through the third excited Kramers doublet, owing to the increased axial magnetic anisotropy and weaker transverse magnetic anisotropy. As a result, pronounced magnetic hysteresis loops up to 14 K are observed, and the effective energy barrier (Ueff = 1025 K) for relaxation of magnetization reached a breakthrough among the SMMs.

Structure and bonding of Cu bis-dithiolenes complexes: a theoretical study

Metal dithiolene complexes are now a well-established class of coordination compounds, and considerable attention has been directed toward developing synthetic routes and studying the reaction chem...

Studies of biologically potent organotin(IV) and organosilicon(IV) complexes of a sulfur donor ligand derived from 1‐acetylferrocene

AbstractThe coordination and organometallic chemistry of metal–nitrogen‐ and metal–sulfur‐bonded compounds have come to occupy a prominent position in research due to their economical importance in the field of agricultural, medicinal and industrial chemistry. Although Schiff bases of ferrocene derivatives and their metal complexes with lanthanide and transition metal ions have been synthesized and some of their structures characterized, their interaction with main group metal ions and the formation of their coordination complexes are subjects of current interest. This communication deals with a description of synthetic procedure and structural characterization on the basis of analytical and spectroscopic techniques of a new class of coordination compounds of organotin(IV) and organosilicon(IV) with a sulfur‐containing ligand moiety derived by the condensation of 1‐acetylferrocene and thiosemicarbazide. Finally, attempts have been made to establish a correlation between a variety of biointeraction activities, including antimicrobial activity and antifertility activity, on male rats and the structures of the resulting products on the basis of different constituents and chemical phenomena. Copyright © 2002 John Wiley & Sons, Ltd.

Thermal stability of some polynuclear coordination compounds in the systems Ln(III)-Co(II)-oxalate

This paper reports an investigation of the thermal stabilities of the class of coordination compounds containing lanthanide ions Ln(III) (Ln=La, Sm, Eu, Dy, Er), Co(II) ions and oxalate anions C2O42−. The thermal decomposition steps were identified, and in some cases the values of the non-isothermal kinetic parameters were determined.

Photochemistry and photophysics of coordination compounds: An extended view

Coordination chemistry is much more than the coordination of transition-metal ions by organic or inorganic ligands. Its scope extends to the binding of all kinds of substrates (cationic, anionic, and neutral molecular species). Therefore coordination chemistry merges into the big field of supramolecular chemistry. Coordination compounds (with or without metals) exhibit by definition a high level of organization and therefore they are quite suitable to exploit the energy and information content of photons. In this paper we illustrate specific examples concerning the similarity between the photochemical behavior of classical coordination compounds (i.e. metal complexes) and supramolecular species not containing metals. We also describe coordination compounds not containing metals that undergo photochemically, electrochemically, or chemically induced mechanical movements (molecular-level machines) and behave as logic gates.