Mixed-ligand Coordination Compounds Research Articles

Spectroscopic and thermal studies of mixed ligand coordination compounds of cobalt (II) with aspartic and dicarboxylic acids

The synthesis of complex compounds of cobalt (II) ion in the presence of aspartic and dicarboxylic acids has been studied by thermal and spectroscopic methods. Thermal decomposition processes of these compounds are studied on the basis of thermal analysis, and endo- and exoeffects are determined. The decomposition products of the compounds were studied on the basis of mass reduction by the thermogravimetric method. Based on the results of spectroscopic studies, the structural formulas of the synthesized coordination compounds are established.

Cadmium and silver complexes of a pyridine containing ligand: syntheses, structural studies, biological activity and docking studies.

The current study aimed to synthesize seven new metal coordination complexes (Q1-Q7) with potential biomedical applications. Novel mononuclear, polynuclear and mixed-ligand coordination compounds of the elements, cadmium(ii) and silver(i) derived from a pyridine containing ligand (2,4,6-tris-(2-pyridyl)-1,3,5-triazine (TPT)) have been synthesized successfully with the general formulae [Cd(TPT)Cl6]·H2O and [Ag x (TPT) y (L)2(ClO4)](ClO4) z (x = 1,2,3, y = 1,2,3, L = PPh3 or phen, z = 1,2). The structural features were fully characterized using various spectroscopic techniques, such as infrared, ultraviolet-visible spectroscopy, 1D and 2D-NMR (1H, 13C, 31P, 1H-1H COSY and 1H-13C HSQCAD), CHN analysis, molar conductance (Λ), thermogravimetric analysis (TGA), and powder X-ray diffraction analysis. The structure of complex Q6 was also confirmed by single-crystal X-ray analysis. The luminescence and electrochemical properties of complexes, in solution, have been studied. X-ray crystallographic determination of the [Ag(TPT)(PPh3)2]ClO4·EtOH (Q6) complex shows that the Ag+ cation is bonded to one tridentate TPT ligand through NNN set of donor atoms and two triphenylphosphine ligands, giving the Ag+ a distorted trigonal bipyramidal geometry. X-ray powder diffraction analysis showed that metal complexes Q3, Q6 and Q7 display crystalline peaks. The complexes were evaluated for their in vitro antibacterial efficacy against various bacterial and fungal species. The in vitro efficacy against the MCF-7 human breast cancer cell line was assessed to determine the anticancer activities. The tri-nuclear silver complex Q3 shows great potential as a therapeutic candidate for treating breast cancer, since it exhibits a half-maximal inhibition concentration (IC50) of 13.45 ± 0.9 μM. Molecular docking simulations were also carried out to evaluate the interaction strength and properties of the metal complexes with selected cancer and bacteria relevant proteins namely cyclin-dependent kinase 2 (CDK2), cyclin-dependent kinase 6 (CDK6), signal transducer and activator of transcription 3 (STAT3), and beta-lactamases from Escherichia coli and Staphylococcus aureus.

Salts and double tartratogermanates/stannates of 3d-metals as modifiers of unsaturated oligoesters

The paper presents the results of the systematic research into effects of 3d-metals acetates, acetylacetonates and double tartrategermanates/stannates on the modification of polyglycol maleine phthalate. The copolymerization parameters of the prepared modified oligoesters with methyl methacrylate monomer and threeethyleneglycoldimethacrylate oligomer were determined. Modifiers were added to the reaction mixture before the start of polycondensation of maleic and phthalic anhydrides with ethylene glycol at the temperature of 1750C. The kinetics of copolymerization at the initial stages was determined by the dilatometry at the temperatures of 500C to 600C. It was established that the modification of polyglycol maleinate phthalate with the studied compounds allows significantly increasing the rate and reducing the temperature coefficient of the copolymerization reaction. There advantages of the investigated double multi-metal mixed ligand coordination compounds as modifiers were proved as compared to the standard industrial systems, acetylacetonates and metal acetates. The presented modifiers are able to improve significantly the characteristics of the semi-finished products in the industrial manufacturing of copolymers without the significant change of the technological process.

Mixed ligand Cd(II) coordination architectures based on bulky anthracene-9-carboxylate ligand: Crystal structures and optical properties

The reaction of cadmium nitrate with anthracene-9-carboxylic acid (HL) and two terpyridine derivatives, 4′-phenyl-2,2′:6′,2″-terpyridine (L1) and 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine (L2), led to the formation of two mixed-ligand coordination compounds, [Cd(C21H15N3)(C15H9O2)2] (1) and [Cd2(C20H14N4)2.5(C15H9O2)4]n (2). Coordination compounds were characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR, UV–Vis and luminescence spectroscopy. X-ray analysis of prepared coordination compounds reveals that 1 is single nuclear coordination complex, whereas 2 is a one-dimension coordination polymer with zigzag chain structure. The nature of L1 and L2 ligands has an essential influence on the molecular geometry and assembly, as well as on the physicochemical properties of complexes 1 and 2. Finally, 1D polymer 2 was utilized as a precursor for the fabrication of an organic light-emitting diode (OLED@2) whose emission wavelengths were investigated at different voltage.

New mixed ligand complexes of alkaline earth metal cations containing nicotinamide and diphenic acid. Synthesis and structural properties

Mixed-ligand coordination compounds containing neutral nicotinamide and monoanionic diphenate organic molecules of alkaline earth metal cations, Mg2+ (C40H38MgN4O14) (I), Ca2+ (C40H34CaN4O2) (II), Sr2+(C40H34N4O2Sr) (III) and Ba2+(C40H34BaN4O2) (IV) were synthesised. Chemical composition analysis, single crystal XRD, spectroscopic, and thermal analysis methods were used to determine the structural properties of the compounds obtained. According to the data obtained from a single-crystal XRD analysis of the Mg2+ complex, the coordination environment of the metal cation was surrounded by four aqua and two nicotinamide ligands to form a distorted octahedral geometry. The charge balance of the complex sphere was provided by two diphenate ligands placed mono-anionically outside the coordination sphere. The structure is a salt-type complex. Since crystals suitable for single crystal structure analysis of other metal cations complexes (II, III and IV) could not be formed, the structural properties were tried to be explained by chemical composition analysis, spectroscopic, and thermal analysis methods. Accordingly, it is found that the coordination circles of metal cations are octahedral and all ligands (two aqua, two neutral nicotinamide, and two monoanionic-double-toothed diphenate) coordinate with the metal in the coordination sphere. The geometries of the complexes are detected to be of distorted cubic structure.

Heteroligand Metal Complexes with Extended Redox Properties Based on Redox-Active Chelating Ligands of o-Quinone Type and Ferrocene.

A combination of different types of redox-active systems in one molecule makes it possible to create coordination compounds with extended redox abilities, combining molecular and electronic structures determined by the features of intra- and intermolecular interactions between such redox-active centres. This review summarizes and analyses information from the literature, published mainly from 2000 to the present, on the methods of preparation, the molecular and electronic structure of mixed-ligand coordination compounds based on redox-active ligands of the o-benzoquinone type and ferrocenes, ferrocene-containing ligands, the features of their redox properties, and some chemical behaviour.

Novel mixed ligand coordination compounds of some rare earth metal cations containing acesulfamato/N,N-diethylnicotinamide.

The mixed ligand coordination compounds containing acesulfamato and N,N -diethylnicotinamide biomolecules of some rare earth metal cations (Eu3+, Tb3+, Ho3+, Er3+ and Yb3+) were synthesized, and their structural properties were investigated. Possible structural formulas have been proposed by determining the chemical composition of molecules (elemental analysis), binding properties (infrared spectroscopy, mass analysis, solid-state UV-vis spectroscopy), thermal degradation properties (TGA / DTA curves). Based on the data collected, it is suggested that rare earth metal cations with a 3+ oxidation state have sextet coordination. The geometries of the structures were thought to be distorted octahedral. The charge balance of the coordination sphere is balanced by a monoanionic acesulfamato located outside the coordination sphere. When the thermal behaviours of the complexes were examined, it was determined that the compounds with Eu3+, Tb3+, and Yb3+ metal cations contained one hydrate water outside the coordination sphere. Hydrate waters do not exist in the Ho3+ and Er3+ metal cation-centred complexes. At the end of the thermal decomposition analysis of all complex structures, it was determined that they leave the relevant metal oxides in the reaction vessels as final decomposition products.

Mn(II) and Co(II) mixed-ligand coordination compounds with acesulfame and 3-aminopyridine: synthesis and structural properties

Two mixed ligand complexes containing acesulfame (acs) and 3-aminopyridine (3-ap) ligands of Mn(II) and Co(II) were synthesized. The obtained compounds were characterized by various analysis methods. The geometries of complexes, C18H28MnN6O12S2 (1) and C18H32CoN6O14S2 (2), are distorted octahedra. Coordination of metal cations is provided by two molecules of 3-ap and four water ligands. In both structures, the 2+ charge of the metal required two monoanionic acs molecules located outside the coordination sphere. Complex 1 contains no hydrate water, while 2 contains two molecules of hydrate water. The crystal system of 1 is monoclinic and space group P21/c, while the crystal system of 2 is triclinic and space group P-1. Data on the removal of hydrate and crystalline waters in structures from thermal analysis curves support the described molecular structures. The bending vibrations of the bonds obtained from the FT-IR spectra match the crystal structure described. As a result of thermal analysis of both complexes, it was determined that the relevant metal cations remained in the reaction vessel as oxide (MnO and CoO) residues.

Syntheses, Characterization and Biological Activity of Coordination Compounds of 3-Hydroxy-2-methyl-4<i>H</i>-pyran-4-one and Its Mixed Ligand Complexes with 1,2-Diaminocyclohexane

Coordination compounds of 3-hydroxy-2-methyl-4H-pyran-4-one with iron(III), cobat(III) and chromium(III) were synthesized with M:L (1:2). Mixed ligand coordination compounds of 3-hydroxy-2-methyl-4H-pyran-4-one and 1,2-diaminocyclohexane using the same metal ions were also synthesized M:L1:L2 (1:1:1) where L1 is 3-hydroxy-2-methyl-4H-pyran-4-one and L2 is 1,2-diaminocyclohexane. The coordination compounds obtained were characterized using electronic and infrared spectral analyses, magnetic susceptibility and percentage metal analysis. They were also evaluated for their cytotoxic and antioxidant activities. The result obtained suggested that octahedral geometry was obtained for all the compounds, as a result of additional two molecules of the solvent coordinated to the metal ions. Both the primary and secondary ligands coordinated in a bidentate fashion. The synthesized compounds exhibited moderate cytotoxicity, although none was as active as the standard. The cobalt(III) mixed ligand complex elicited the highest activity. The synthesized compounds all exhibited good to moderate antioxidant activity.

New method for the synthesis of heterospin metal complexes with nitroxides

A new approach was developed to synthesize transition metal complexes with nitroxides based on the simultaneous involvement of nitronyl nitroxide and imino nitroxide in the reaction with metal. It was shown that the reaction of a metal with nitronyl nitroxide can afford a metal complex containing two different radicals in the metal coordination sphere in the case when imino nitroxide is generated in the reaction medium via a redox process. The reaction of a metal with imino nitroxide also can give mixed-ligand complexes, in which the metal coordinates both the starting imino nitroxide and its reduction product — the corresponding amidine oxide. This compound can be prepared by an alternative synthesis using the reaction of metal with sterically hindered amidine oxide, resulting in the formation of mixed-ligand coordination compounds through the coordination of both the starting amidine oxide and its oxidation product — imino nitroxide. In the latter case, the following conditions have to be met: the reaction should be performed in the presence of oxygen and transition metal, which can easily change its oxidation state under ambient conditions (CoII, MnII, FeII). To synthesize mixed-ligand complexes with transition metals that are not prone to change the oxidation state under ambient conditions (NiII, ZnII), a specially prepared mixture of nitronyl nitroxide and imino nitroxide should be added to the reaction mixture. It is worth noting that the reaction can be performed using nitronyl nitroxide and imino nitroxide belonging to different series, which significantly extends the scope of the method.The bibliography includes 156 references.

COORDINATION COMPOUNDS OF COPPER, COBALT AND NICKEL FORMATES WITH FORMAMIDE AND CARBAMIDE

The synthesis of mixed ligand coordination compounds of copper, cobalt and nickel formates with formamide and urea in an aqueous solution was carried out. The metal content in the complexes was determined by complexometric titration. Using IR spectroscopy, it was proved that the coordination of formamide and urea with the complexing atom is carried out through the oxygen atom of the carbonyl group. The absorption spectrum of coordinated water is also present in the IR spectrum. The nature of the change in the frequency of stretching vibrations of the –OH group in the composition of water indicates its location in the nearest coordination sphere of the central atom. Derivatographic analysis investigated the thermal behavior of the obtained compounds. Based on the nature of the heating curves, sequential cleavage of water and ligands is shown and a molecular formula for synthesized compounds is proposed. The equation of the synthesis reaction of these coordination compounds is also given.

Synthesis, Structure and Application of Mixed-Ligand Coordination Compounds of Copper(II) with Substituted Thioamides

Synthesis, Structure and Application of Mixed-Ligand Coordination Compounds of Copper(II) with Substituted Thioamides

The Coordination Compound of Ga(III) with Stillbazo in the Presence of Cetyl Pyridinium Chloride as a Surface Active Compound

The coordination compound of gallium (III) with stillbazo-stillbene-4,4'-bis [(1-azo)3,4-dihydroxybenzene]-2,2'-disulfonic acid has been investigated by spectrophotometric method in the presence of cetyl pyridinium chloride (CPC) as surface active compound. It has been determined that the mixed ligand complexes were formed with the ratio of 1:2:4 in CPC-mediated phase. The molar coefficient and the stability constant of the complex compound βк = 6.8 × 109, eк = 66,834 have been studied by various spectrophotometric methods. The effect of pH, time, temperature, concentration of the reagents and CPC on formation of the unmixed and mixed ligand coordination compounds has been also studied. It has been determined that the Beer’s law is respected within 0.008 - 10 μg of Ga(III) in 25 mL solution. The technique of the photometric determination of gallium in natural compositive objects and industrial objects has been developed.

Mixed-ligand coordination compounds based on the rigid 4,4′-bis(1-imidazolyl)biphenyl and pyridinedicarboxylate ligands

The mixed-ligand binuclear complexes [Co2(BIBP)(2,6-PDC)2(H2O)4] (1), [Ni2(BIBP)(2,6-PDC)2(H2O)4] (2), and the coordination polymers 1D-{[Zn(BIBP)(2,6-PDC)]·4.5H2O}n (3), 2D-[Ni2(BIBP)(2,5-PDC)2(H2O)4]n (4), and 3D-{[Ni2(BIBP)3(2,3-PDC)2]·3.75H2O}n (5) were synthesized in good yields, characterized by IR, thermogravimetry and single X-ray diffraction method (BIBP = 4,4′-bis(1-imidazolyl)biphenyl, 2,6-PDC = 2,6-pyridinedicarboxylate, 2,3-PDC = 2,3-pyridinedicarboxylate, 2,5-PDC = 2,5-pyridinedicarboxylate). Compounds 1 and 2 are binuclear complexes, compound 3 is a 1D polymer, 4 has a 2D laminated structure, and 5 represent a 3D framework. A common motif in the structures, independent of their dimensionality is the bridging action of the neutral BIBP ligand between two metal ions and a metal chelating coordination of the dianionic PDC ligand through the pyridine nitrogen atom and the carboxylate group in 2-position. The comparative single crystal X-ray structure investigations reveal the fine-tuning influence of the carboxylic group positions in the pyridinedicarboxylate (PDC) ligands and the metal nature on the final structure topology and dimensionality. Compounds 1 and 2 are isostructural and represent Co(II) and Ni(II) isomorphs, where the metal ions coordinate two water molecules and the 2,6-PDC ligand in ONO chelate mode, while the bidentate BIBP ligand link the metal ions into a dinuclear complex. In 3 the 2,6-PDC ligand coordinates to the zinc atom in the same ONO chelate mode and two bridging BIBP ligands give a coordination number of five and extend the structure to a 1D polymer with an enantiopure triple-stranded helix motif in a case of spontaneous resolution in the chiral tetragonal space group P4322. In 4 the 2,5-PDC ligand realises its chelate-bridging function and together with the bridging BIBP ligand form 2D layers with the Ni(II) atoms with hcb (honeycomb or 6,3) topology. In 5 the chelate-bridging 2,3-PDC and BIBP ligands form (4,4)-layers which are interlinked by additional BIBP pillars to a 3D network with two-fold interpenetration of symmetry-related networks.

Two mixed-ligand coordination compounds: crystal structure and anti-liver cancer activity

Two 3D mixed-ligand coordination compounds, [Cd(1,3-bdc)(bmip)]n [1, H21,3-bdc = 1,3-benzenedicarboxylic acid, bmip = 1,3-bis(2-methyl-1H-imidazol-1-yl)propane] and [Cd(5-mpc)(bmip)]n (2, H25-mpc = 5-methylisophthalic acid), have been successfully synthesized under hydrothermal conditions and characterized successfully by single crystal X-ray analysis. In addition, in vitro anticancer activities of compounds 1 and 2 on three human liver cancer cells (PLC/PRF/5, BEL-7404 and MHCC97-L) were further determined.

Europium and yttrium complex formation with β-diketones and amino acids

Europium(III) and yttrium(III) complexation processes in the extraction systems with β-diketones and amino acids were studied. The increase in the lanthanide distribution ratios in these systems is caused by the formation of mixed-ligand coordination compounds of lanthanides in these systems. The formation of mixed-ligand coordination compounds of lanthanides with β-diketones and amino acids in the organic phase was confirmed by IR and luminescence spectroscopy and quantum chemical calculations of the formation energies of mixed-ligand yttrium complexes with glycine and acetylacetone or hexafluoroacetylacetone. It was found that amino acid molecules form mixed-ligand compounds with lanthanide β-diketonates by coordinating the lanthanide ion by the oxygen ion of the carboxy group with retention of the betaine structure, while the amino acid NH3+ group is hydrogen-bonded to one oxygen atom of β-diketone. The possibility of effective use of europium tris-dibenzoylmethanate as a glycine receptor is demonstrated.

Aminobenzonitrile isomers-mediated self-assembly of mixed-ligand silver(I) coordination architectures: Synthesis, structural characterization and properties

Three mixed-ligand coordination compounds (CCs) of the formula {[Ag( p-abn)(dnca)]·H 2O} n ( 1), {[Ag( o-abn)(dnca)]·H 2O} n ( 2), and {[Ag( m-abn) 4)]·(dnca)·H 2O} ( 3) (where p-abn = 4-aminobenzonitrile, o-abn = 2-aminobenzonitrile, m-abn = 3-aminobenzonitrile, Hdnca = 3,5-dinitrobenzoic acid) were synthesized by reactions of Ag 2O and aminobenzonitrile ligands with Hdnca under the ammoniacal condition. All CCs have been structurally characterized by element analysis, IR and X-ray single-crystal diffraction. The aminobenzonitrile acts as bidentate μ 2- N,N′ ligand in both 1 and 2, and as monodentate ligand in 3. As the change of the relative position of amino and cyano groups of aminobenzonitrile ligands, the dimensionality of 1–3 decreases from 2D to 0D mainly due to the steric effect of the substituted groups, which indicates that aminobenzonitrile isomers play important roles in the formation of the diverse coordination architectures. The three CCs exhibit photoluminescent emissions in the solid state at room temperature.

Mixed-ligand complexes [Cd(DMSO)5(NCS)][Cr(NH3)2(NCS)4] · 3DMSO and [Mn(DMSO)4(H2O)2][Cr(NH3)2(NCS)4]2 · 6DMSO · 2H2O: Syntheses and crystal structures

New mixed-ligand coordination compounds[Cd(DMSO)5(NCS)][Cr(NH3)2(NCS)4] · 3DMSO (I) and [Mn(DMSO)4(H2O)2][Cr(NH3)2(NCS)4]2 · 6DMSO · 2H2O (II) have been synthesized and studied by IR spectroscopy and X-ray diffraction analysis. The crystals of compound I are monoclinic, a = 14.5275(7), b = 23.1692(11), c = 14.6969(6) A, β = 97.057(2)°, V = 4909.4(4) A3, space group P21/c, Z = 4, ρcalcd = 1.507 g/cm3, R = 0.0556. The crystals of compound II are triclinic, a = 11.7784(3), b = 12.1760(3), c = 13.1922(2) A, α = 85.5420(10)°, β = 87.9000(10)°, γ = 70.3680(10)°, V = 1776.46(7) A3, space group P $$ \overline 1 $$ , Z = 1, ρcalcd = 1.444 g/cm3, R = 0.0350.

Synthesis and luminescent properties of the complexes EuL(i-Bu2PS2)2(NO3) (L = Phen, 2,2′-Bipy, 4,4′-Bipy)

The mixed ligand coordination compounds EuL(i-Bu2PS2)2(NO3) (L = Phen, 2,2′-Bipy, 4,4′-Bipy) are synthesized. On the basis of X-ray analysis and IR spectra their structures are elucidated. The complexes containing Phen or 2,2′-Bipy are found to possess photoluminescent property.

Crystal and molecular structures of ZnPhen(C2H5OCS2)2 and Zn(2,2′-Bipy)(n-C4H9OCS2)2 mixed-ligand coordination compounds

ZnPhen(EtOCS2)2 (I) and Zn(2,2′-Bipy)(n-BuOCS2)2 (II) mixed-ligand complexes have been synthesized. The structures were solved from X-ray diffraction data (CAD-4 and X8-APEX diffractometers, MoKα radiation, 1879 and 3637 Fhkl, R = 0.0374 and 0.0315). Crystals I are monoclinic with parameters a = 11.678(3) A, b = 19.215(3) A, c = 9.655(1) A; β = 101.23(1)°; V = 2125.0(7) A3; Z = 4, space group P21/c; crystals II are triclinic with parameters a = 8.7875(3) A, b = 11.833(1) A, c = 13.3454(6) A; α = 112.154(2)°, β = 108.503(1)°, γ = 92.787(2)°; V = 1196.2(1) A3; Z = 2, space group 1 \(P\bar 1\). The structures are composed of discrete mononuclear molecules. The polyhedra of the Zn atoms are distorted trigonal bipyramids N2S3 formed by coordination of the N atoms of Phen or 2,2′-Bipy molecules and sulfur atoms of the monodentate and cyclic bidentate xanthogenate ligand. In structures I and II, dimer assemblies are formed by π-π interactions of Phen or 2,2′-Bipy molecules.