Dioxime Ligand Research Articles

UFO-shaped heteronuclear 3d–4f metal clusters: Synthesis, structure, and magnetic properties

Coordination molecule clusters assembled from a large number of metal ions and organic ligands are structurally and functionally challenging to characterize. Here, a series of new hetero-metallic nano-clusters {Mn6Ln2} (Ln = La 1, Ce 2, Sm 3, Gd 4) were obtained via solvothermal method. These complexes possess unique crystalline structures with vertex-sharing UFO-shaped [Mn6Ln2] cores. Interestingly, adjacent cluster molecules can further form a three-dimensional framework structure through π-π stacking interaction between acenaphthenequinone dioxime ligands. Magnetic tests show strong ferromagnetic exchange interactions within the {Mn6Ln2} clusters.

New schiff base ligand type [LH2] donor derevative from 4-Aminophenol with Manganese (II), Cobalt(II), Nickal(II), and Copper(II)

The condensation reaction between dimethylglyoxime, acetic acid, and 4-aminophenol was significantly influenced by the [LH2] type donor derivative ligand. The reaction was conducted in methanol for 24 hours while being stirred and refluxed. The syntheses forming a new (2E,3E)-butane-2,3-dione O2-((E)-1-((4-hydroxyphenyl)imino)ethyl) O3-((Z)-1-((4-hydroxyphenyl)imino)ethyl) dioxime) dioxime ligand type [LH2]. Spectroscopic techniques (FT-IR and UV-Vis), elemental analysis (CHN), magnetic susceptibility testing, thin-layer chromatography (TLC), X-RD powder diffraction, 1H-NMR molar conductance, and other methods have been used to characterize the ligand and its complexes with the general formula [M(LH2)] where [M= Mn(II), Co(II), Ni(II), and Cu(II), and [LH2] = donor atoms ligand with N4 and O]. Our study reveals the formation of a new ligand and new complexes with trigonal bipyramid geometrical shape around the Manganese(II), Cobalt(II), Nickel(II), and Copper(II) metal ions. Biological function using the agar disc diffusion method for the ligand and its complexes showed considerable activity against one kind of bacteria (Staphylococcus aureus) after being exposed to two types of bacteria (Staphylococcus aureus and Escherichia coli).

Ruthenium(ii) arene complexes bearing simple dioxime ligands: effective catalysts for the one-pot transfer hydrogenation/N-methylation of nitroarenes with methanol

Ruthenium(ii) η6-arene complexes with easily-available dioxime ligands are efficient catalytic precursors for the selective reduction/N-methylation of aromatic nitrocompounds with methanol.

Acid/base responsive assembly/dis-assembly of a family of zirconium(IV) clusters with a cyclic imide-dioxime ligand.

The hydrolytically stable dioxime ligand (2Z-6Z)-piperidine-2,6-dione (H3pidiox) acts as a strong chelator mainly with hard metals in high oxidation states, a pre-requisite for potential applications in metal sequestering processes from aqueous solutions. Reaction of ZrCl4 with H3pidiox in methanol gives the mononuclear compound [ZrIV(η1,η1,η2-H2pidiox-O,N,O')2(OH2)2]Cl2·H2O·CH3OH (1), while the same reaction mixture in the presence of KOH gave the pentanuclear ZrOC [ZrIV5(μ2-OH)4(OH2)4(μ2-η1,η1,η2-Hpidiox-O,N,O')4(η1,η1,η1-HpidioxO,N,O')4]·5KCl·3CH3OH·8H2O (2). Compound 1 is formed at very acidic pH = 0, and the pentanuclear ZrOC 2 at higher pH values (pH = 2). Compounds 1 and 2 were characterized by single crystal X-ray structure analysis, multi-nuclear NMR spectroscopy and ESI-MS spectrometry. The single crystal X-ray structure analysis of 1 revealed a mononuclear zirconium(IV) compound containing an eight-coordinate zirconium atom bound to two singly deprotonated H2pidiox- ligands and two water molecules in a severely distorted bicapped octahedral geometry. The pentanuclear ZrOC 2 constitutes the second example of a Zr5 cluster to be reported and the first one in which the four zirconium atoms are arranged in a tetrahedral arrangement with the fifth occupying the center of the tetrahedron. 1D and 2D NMR spectroscopies of the acidic CD3OD solutions of complex 1 reveal a fast equilibrium between 1 and 2. Addition of KOH into a CH3OH solution of 2 results in the controlled fast transformation of 2 to an asymmetric hexanuclear ZrOC 3 as evidenced by the NMR and real-time ESI-MS solution studies. Further addition of KOH to the solution of 3 leads to the ZrOC 4, and on the basis of NMR and ESI-MS data and in comparison with the known hexanuclear titanium(IV)/H3pidiox cluster, it is concluded that the cluster 4 should have a hexanuclear structure. Electrospray ionization mass spectrometry (ESI-MS) demonstrated not only the structural stability 1 and 2 in solution, but also revealed the reversible pH driven dis-assembly/re-assembly process between the monomeric 1 and the pentanuclear ZrOC 2.

Spontaneous reaction and self-assembly of copper nitrate and cyclic 1,3-dione dioximes into multicopper complexes

We have found that Cu(NO3)2 and 1,3-dione dioxime afford a variety of multicopper complexes under ambient conditions. Specifically, Cu(NO3)2 and cyclohexane-1,3-dione dioxime gave a trinuclear complex in which the central α-carbons of the three dioxime ligands are oxidized into carbonyl groups, two of which were further reacted with solvent MeOH to give a hemiacetal structure. On the other hand, Cu(NO3)2 and cyclopentane-1,3-dione dioxime gave a dinuclear complex in which Cu(II) was reduced to Cu(I) and two of the three ligands couple to give the fulvalene structure. Together with the previously reported reaction of Cu(NO3)2 and pentane-2,4-dione dioxime into a pentanuclear complex in which the four ligands were changed into trioximes, surprisingly rich chemistry has been discovered for combinations of Cu(NO3)2 and 1,3-dione dioximes.

Crystal structure of di-ammonium bis-[tris-(oxamide dioxime-κ2 N,N')nickel(II)] bis-[tris-(oxalato-κ2 O,O')chromate(III)] 6.76-hydrate.

The asymmetric unit of the title compound, (NH4)2[Ni(C2H6N4O2)3]2[Cr(C2O4)3]2·6.76H2O, comprises two NH4 + cations, two [Ni(C2H6N4O2)3]2+ cations and two [Cr(C2O4)3]3- anions, as well as eight water mol-ecules of crystallization of which only one is fully occupied. In the cationic and anionic complexes, the central atoms (NiII and CrIII) are each surrounded by three bidentate ligands (N-chelating oxamide dioxime and O-chelating oxalate, respectively), resulting in distorted octa-hedral coordination spheres. In the crystal, O-H⋯O hydrogen bonds between the oxamide dioxime ligands as donor groups and the oxalate ligands as acceptor groups alternately connect the cationic and anionic complexes into infinite pillars extending parallel to [100]. Moreover, N-H⋯O hydrogen bonds between the same ligands connect neighboring pillars, thus delineating channels that accommodate the charge-balancing NH4 + cations as well as the water mol-ecules of crystallization. Although the H atoms could not be localized for these two species, the corresponding N⋯O and O⋯O distances indicate hydrogen bonds of medium strength.

Mechanistic studies on the in-situ generation of furoxan ring during the formation of Cu(II) coordination compound from dioxime ligand: Theoretical and experimental study

The copper(II) coordination compound, [Cu(Lʹ)(NO3)2] (1) where Lʹ = 3,4-di(pyridin-2-yl)-1,2,5-oxadiazole 2-oxide, was synthesized from the reaction of Cu(NO3)2·3H2O and dioxime ligand, (1E,2E)-1,2-di(pyridin-2-yl)ethane-1,2-dione dioxime (L), in methanol under aerial atmosphere. The dark-blue crystals of 1 were obtained by solvent evaporating method and were characterized by elemental analysis, FT-IR spectroscopy and single crystal X-ray studies. Structural studies indicated that in 1 a furoxan ring is generated during the formation of mononuclear Cu(II) coordination compound from the in-situ intramolecular cyclization reaction of dioxime moiety of the initial ligand. The density functional theory (DFT) along with B3LYP functional was employed to propose a rational mechanism for cyclization of dioxime (L) and formation of the furoxan ring in 1. It was found that the isolated ligand (L) is not an acidic compound while its acidity is enhanced dramatically in coordination compound in the presence of NO3− anions assisting its deprotonation. Ring formation is catalyzed by Cu in the second deprotonation step, i.e. Cu(II) accepts the negative charge of L, produced upon deprotonation, to assist formation of the neutral aromatic furoxan ring. In the last step, Cu(I) is oxidized to Cu(II) by solvated oxygen, O2(CH3OH)n, to retrieves its structure and oxidation state.

Single‐armed salamo‐like dioxime and its multinuclear Cu (II), Zn (II) and Cd (II) complexes: Syntheses, structural characterizations, Hirshfeld analyses and fluorescence properties

Three multinuclear Cu (II), Zn (II) and Cd (II) complexes, [Cu2(L)(μ‐OAc)]·CHCl2 (1), [Zn2(L)(μ‐OAc)(H2O)]·3CHCl3 (2) and [{Cd2(L)(OAc)(CH3CH2OH)}2]·2CH3CH2OH (3) with a single‐armed salamo‐like dioxime ligand H3L have been synthesized, and characterized by FT‐IR, UV–vis, X‐ray crystallography and Hirshfeld surfaces analyses. The ligand H3L has a linear structure and C‐H···π interactions between the two molecules. The complex 1 is a dinuclear Cu (II) complex, Cu1 and Cu2 are all five‐coordinate possessing distorted square pyramidal geometries. The complex 2 also forms a dinuclear Zn (II) structure, and Zn1 and Zn2 are all five‐coordinate bearing distorted trigonal bipyramidal geometries. The complex 3 is a symmetrical tetranuclear Cd (II) complex, and Cd1 is a hexa‐coordinate having octahedral configuration and Cd2 is hepta‐coordinate with a pentagonal bipyramidal geometry, and it has π···π interactions inside the molecule. In addition, fluorescence properties of the ligand and its complexes 1–3 have also been discussed.

Pd(II) supported dioxime functionalized Fe3O4 nanoparticles as efficient, eco-friendly and reusable catalysts for the Suzuki-Miyaura cross-coupling reaction in water

Five novel dioxime ligands (L(1-5)H2) were synthesized in various yields under suitable conditions. Novel nano-Fe3O4-supported compounds (Fe3O4/L(1-5)) based on dioxime ligands were also prepared. Subsequently, hybrid materials Fe3O4/L(1-5)/Pd(II) were fabricated by the reaction of Fe3O4/L(1-5) with Pd(AcO)2 in acetonitrile. All synthesized nanoparticles were characterized by FT-IR spectroscopy, scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDX), X-ray diffraction (XRD), inductively coupled plasma analysis (ICP), differential scanning calorimetry (DTA), and thermogravimetric analysis (TGA). The spectroscopic results show that the magnetite (Fe3O4) nanoparticles are in nano size since crystal sizes are < 100 nm. The particles have an average size of about 9.4–23.3 nm. The powder XRD confirmed that the synthesized Fe3O4, Fe3O4/L(1-5), and Fe3O4/L(1-5)/Pd(II) MNPs possess cubic structure having the lattice parameter between 8.31 and 8.40 Å. The structure and the lattice parameters are in good agreement with the literature reported data. The Fe3O4/L(1-5)/Pd(II) nanocatalysts showed high activities in the Suzuki-Miyaura cross-coupling of different aryl halides including iodides, bromides and even chlorides with phenylboronic acid under green and aerobic conditions. More importantly, the reusability experiments revealed that Fe3O4/L(1-5)/Pd(II) catalysts were durable by almost maintaining their inherent activity after 5 catalytic cycles.

Synthesis, structural and physicochemical characterization of a new type Ti6-oxo cluster protected by a cyclic imide dioxime ligand.

Reaction of the cyclic ligand (2Z,6Z)-piperidine-2,6-dione dioxime with TiCl4 and KOH yielded the hexanuclear cluster K6[TiIV6(μ3-O)2(μ2-O)3(CH3O)6(μ2-η1,η1,η2-Hpidiox-O,N,O')4(μ2-η1,η1,η2-pidiox-O,N,O')2]·7.5CH3OH possessing a new {Ti6O5} structural motif. The cluster core {Ti6O5} is wrapped by external tripodal imide dioxime ligands, showing good solubility and stability and thus, allowing its solution to be studied by means of electrospray ionization mass spectrometry, electrochemistry and 2D NMR, c. w. EPR and UV-vis spectroscopies. Density Functional Theory (DFT) calculations reveal that the cyclo-Ti3 metallic cores exhibit metallaromaticity which is expected to contribute to the stabilization of this system.

Metal Chelates as Antitumor Agents: Synthesis, Spectroscopic Characterization and Cytotoxic Action of Metal Chelates of New Dioxime Ligand

Metal Chelates as Antitumor Agents: Synthesis, Spectroscopic Characterization and Cytotoxic Action of Metal Chelates of New Dioxime Ligand

The synthesis and investigation of different cobaloximines by spectroscopic methods

In the present work, firstly a novel monoxime (1) and unsymmetric dioxime ligand (LH2) (2) derived from 4-(4-hydroxyphenyl)-2-butanone as ketone was prepared under optimum conditions. Then, the cobaloxime complexes [(LH)2ClCoB] (B = neutral base: 4-DAP = 4-(dimethylamino)pyridine, 4-HP = 4-hydroxypyridine, 4-CP = 4-chloropyridine, 4-MP = 4-methylpyridine, 4-EP = 4-ethylpyridine, 4-TBP = 4-tert-butylpyridine and P = pyridine) (3–9) with respect to varied axial groups were synthesized in a two-necked round-bottom reaction flask by direct contact of dioxime ligand (2), and different neutral base without special requirement of any additional chemical process. The prepared dioxime ligand (2) and its cobaloxime complexes (3–9) were characterized by means of NMR, FT-IR, UV–Vis and LC-MS spectroscopy, melting point and magnetic susceptibility measurements as well as elemental analysis. It is noteworthy that the coordination chemistry of this cobaloxime complexes is versatile, which is closely related to the nature of the unsymmetric dioxime ligand (2) derived from 4-(4-hydroxyphenyl)-2-butanone, as indicated by the results of the corresponding spectroscopic studies. Also, the spectroscopic results demonstrated that the proposed cobaloxime complexes are a six-coordinated species and octahedral geometry.

Quantum Chemical Computational Studies on a vic-Dioxime Ligand and Its Nickel Complex

In this study, the structural and bonding characteristic of 1-(2,6-Dimethylphenylamino)propane-1,2-dione dioxime ligand and its nickel(II) complex were examined by means of quantum chemical computations. Primarily, comprehensive calculations were performed on these compounds at the DFT, HF and semi-empirical levels of theory by using different basis sets. The structural accuracy of ligand and complex were investigated by comparing the calculated values to the bond lengths and angles measured in X-ray structures. Then, comparison of the methods was applied by considering quality factors calculated for different basis sets of each method. The theoretical structural studies on ligand and complex were carried out by UV-Vis, FT-IR and NMR spectral analysis. The calculated vibrational bands, electronic absorption spectrum and NMR chemical shifts were determined to be consistent with the experimental results. In additional, the characteristic of the metal-ligand interactions were demonstrated by natural bond orbital (NBO) analysis.

The Novel bis-dioxime-based and Boronic acid-capped Groups Containing Fe(II) and Co(II) Complexes: Synthesis, Characterization, and Spectroscopy

In the present work, firstly the novel mono oxime (1) and asymmetric dioxime ligand (LH 2 ) (2) derived 4′-hydroxyvalerophenone as ketone were prepared under optimum conditions. Then, the bis-dioxime-based and boronic acid-capped groups containing Fe(II) and Co(II) complexes [(L) 2 M(X) 2 (BA) 2 ] (3-6) (L= Dioxime, M = Fe(II) or Co(II), X= Cl 2 or H 2 O and BA = Butyl boronic acid (BBA) or Ferrocene boronic acid (FBA)) were synthesized in a two-necked round-bottom reaction flask by direct contact of dioxime ligand (2) , and different boronic acid with metal salts (FeCl 2 .4H 2 O or CoCl 2 ) without special requirement of any additional chemical process. The prepared ligands and its Fe(II) and Co(II) complexes were characterized by means of NMR spectra, FT-IR spectra, UV-Vis spectra, LC-MS, melting point and magnetic susceptibility measurements as well as elemental analysis. The spectroscopic results demonstrated that the proposed Fe(II) and Co(II) complexes are a six-coordinated species and octahedral geometry. The infrared spectra (FT-IR) of the Fe(II) and Co(II) complexes indicated the characteristic peak at range 1208-1217 cm -1 cm corresponding υ(B-O) stretching.

Synthesis and use of dioxime ligands for treatment of leukemia and colon cancer cells

Two new vicinal dioxime ligands containing thiosemicarbazone units (L1H2 and L2H2) were synthesized and characterized using 1H NMR, 13C NMR, heteronuclear multiple quantum correlation, mass, infrared and UV–visible spectroscopies, elemental analysis and magnetic susceptibility measurements. In addition, homotrinuclear nickel(II), copper(II) and cobalt(II) complexes with a metal‐to‐ligand ratio of 3:2 for L1H2 and L2H2 were prepared. Synthesis of nickel(II) complex containing a BF2+ bridge was carried out using a precursor hydrogen‐bridged nickel(II) complex via the template effect. All metal–ligand complexes were tested against two human cancer cell lines (HL‐60 and HT‐29) for their antiproliferative and apoptotic activities. The results showed that [Co(L2H)2(H2O)2] and [Ni(L2H)2] exhibited the strongest antiproliferative activity with IpC50 values ranging between 5 and 10 μM, while [Co(L2H)2(H2O)2] and [Ni(L2H)2] both induced necrosis of HT‐29 cells and 60 and 65% apoptosis in HL‐60 cells, respectively.

CuAAC-based assembly and characterization of a ruthenium-copper dyad containing a diimine-dioxime ligand framework.

The design of molecular dyads combining a light-harvesting unit with an electroactive centre is highly demanded in the field of artificial photosynthesis. The versatile Copper-catalyzed Azide-Alkyne Cycloaddition (CuAAC) procedure was employed to assemble a ruthenium tris-diimine unit to an unprecedented azide-substituted copper diimine-dioxime moiety. The resulting RuIICuII dyad 4 was characterized by electrochemistry, 1H NMR, EPR, UV-visible absorption, steady-state fluorescence and transient absorption spectroscopies. Photoinduced electron transfer from the ruthenium to the copper centre upon light-activation in the presence of a sacrificial electron donor was established thanks to EPR-monitored photolysis experiments, opening interesting perspectives for photocatalytic applications.

Novel poly(imide dioxime) sorbents: Development and testing for enhanced extraction of uranium from natural seawater

A new series of amidoxime-based polymer adsorbents were synthesized at the Oak Ridge National Laboratory (ORNL) by electron beam induced grafting of acrylonitrile and itaconic acid onto polyethylene fiber. Hydroxylamine derivatives of poly(acrylonitrile) (PAN) moiety are demonstrated to possess two kinds of functional groups: open-chain amidoxime and cyclic imide dioxime. The open-chain amidoxime is shown to convert to imide dioxime on heat treatment in the presence of an aprotic solvent, like dimethylsulfoxide (DMSO). The formation of amidoxime and imide dioxime was confirmed by 13C CP-MAS spectra. The adsorbents were evaluated for uranium adsorption efficiency at ORNL with simulated seawater spiked with 8ppm uranium and 5gallon seawater in a batch reactor, and in flow-through columns with natural seawater at the Marine Science Laboratory (MSL) of Pacific Northwest National Laboratory (PNNL) at Sequim Bay, WA. The DMSO-heat-treated sorbents adsorbed uranium as high as 4.48g-U/kg-ads. from seawater. Experimental evidence is presented that the poly(imide dioxime) is primarily responsible for enhanced uranium adsorption capacity from natural seawater. The conjugated system in the imide dioxime ligand possesses increased electron donation ability, which is believed to significantly enhance the uranyl coordination in seawater.

Complexation of Lanthanides with Glutaroimide-dioxime: Binding Strength and Coordination Modes.

The complexation of lanthanides (Nd(3+) and Eu(3+)) with glutaroimide-dioxime (H2L), a cyclic imide dioxime ligand that has been found to form stable complexes with actinides (UO2(2+) and NpO2(+)) and transition metal ions (Fe(3+), Cu(2+), etc.), was studied by potentiometry, absorption spectrophotometry, luminescence spectroscopy, and microcalorimetry. Lanthanides form three successive complexes, M(HL)(2+), M(HL)L, and M(HL)2(+) (where M stands for Nd(3+)/Eu(3+) and HL(-) stands for the singly deprotonated ligand). The enthalpies of complexation, determined by microcalorimetry, show that the formation of these complexes is exothermic. The stability constants of Ln(3+)/H2L complexes are several orders of magnitude lower than that of the corresponding Fe(3+)/H2L complexes but are comparable with that of UO2(2+)/H2L complexes. A structure of Eu(3+)/H2L complex, identified by single-crystal X-ray diffractometry, shows that the ligand coordinates to Eu(3+) in a tridentate mode, via the two oxygen atoms of the oxime group and the nitrogen atom of the imide group. The relocation of protons of the oxime groups (-CH═N-OH) from the oxygen to the nitrogen atom, and the deprotonation of the imide group (-CH-NH-CH-) result in a conjugated system with delocalized electron density on the ligand (-O-N-C-N-C-N-O-) that forms strong complexes with the lanthanide ions.

Synthesis of the Multinuclear Cobaloxime Complexes via Click Chemistry as Catalysts for the Formation of Cyclic Carbonates from Carbon Dioxide and Epoxides

In this study, the structurally similar multinuclear cobaloxime complexes based on dioxime ligands were synthesized and characterized as trinuclear complexes with respect to varied axial groups. The multinuclear cobaloxime complexes were characterized by 1H, 13C-NMR, FT-IR, UV-Vis, LC-MS spectra, melting point and magnetic susceptibility measurements. These multinuclear cobaloxime complexes have been successfully applied to the synthesis of cyclic carbonates from CO2 and epoxides under optimized conditions and without using any solvent. All multinuclear cobaloxime complexes obtained by click chemistry are good catalysts for the cycloaddition of CO2 to different epoxides in the presence of pyridine as a co-catalyst. Additionally, the effects of epoxides, bases, temperature, pressure, and time on the yield of cyclic carbonates were investigated. In this study, multinuclear cobaloxime complexes based on dioxime ligands were synthesized and characterized by 1H and 13C-NMR spectra, FT-IR spectra, UV-Vis spectra, LC-MS spectra, melting point measurements and magnetic susceptibility measurements. The multinuclear cobaloxime complexes are good catalysts for the cycloaddition of CO2 to different epoxides in the presence of pyridine as a co-catalyst.

Complexation of Neptunium(V) with Glutaroimide Dioxime: A Study by Absorption Spectroscopy, Microcalorimetry, and Density Functional Theory Calculations.

Complexation of NpO2(+) ions with glutaroimide dioxime (H2L), a cyclic imide dioxime ligand that has been shown to form strong complexes with UO2(2+) in aqueous solutions, was studied by absorption spectroscopy and microcalorimetry in 1.0 M NaClO4 aqueous solutions. NpO2(+) forms two successive complexes, NpO2(HL)(aq) and NpO2(HL)2(-) (where HL(-) stands for the partially deprotonated glutaroimide dioxime ligand), with stability constants of log β111 = 17.8 ± 0.1 and log β122 = 33.0 ± 0.2, respectively. The complexation is both enthalpy- and entropy-driven, with negative enthalpies (ΔH111 = -52.3 ± 1.0 kJ/mol and ΔH122 = -96.1 ± 1.4 kJ/mol) and positive entropies (ΔS111 = 164 ± 3 J/mol/K and ΔS122 = 310 ± 4 J/mol/K). The thermodynamic parameters suggest that, similar to complexation of UO2(2+), the ligand coordinates with NpO2(+) in a tridentate mode, via the two oxygen atoms of the oxime groups and the nitrogen atom of the imide group. Density functional theory calculations have helped to interpret the optical absorption properties of the NpO2(HL)2(-) complex, by showing that the cis and trans configurations of the complex have very similar energies so that both configurations could be present in the aqueous solutions. It is the noncentrosymmetric cis configuration that makes the 5f → 5f transition allowable so that the NpO2(HL)2(-) complex absorbs in the near-IR region.