Oxime Ligands Research Articles

Synthesis, spectra and X-ray crystallography of dipyridin-2-ylmethanone oxime and its CuX2(oxime)2 complexes: Thermal, Hirshfeld surface and DFT analysis

Dipyridin-2-ylmethanone oxime (C11H9N3O), was prepared using di-2-pyridyl ketone. The oxime ligand and its neutral CuX2 (oxime)2 (X = Cl or Br) complexes have been identified with the aid of several spectroscopic techniques such as: IR, EI-MS, EA, UV–visible, TG, 1H-NMR and finally the structure of the free oxime ligand was confirmed by X-ray diffraction studies. The oxime crystallizes in the monoclinic space group P21/c, with cell parameters a = 8.8811 (8) Å, b = 10.6362 (8) Å, c = 11.2050 (8) Å, β = 109.085 (4) º, V = 1000.26 (14) Å3 and Z = 4. The molecular conformation is stabilized by a strong intramolecular OH⋯N hydrogen bonding between the hydroxyl group of the oxime moiety and the nitrogen of the pyridine ring.Since the oxime structure was solved by XRD, the ligand structure parameters like bond length and angles were compared to the DFT computed one, the UV–visible to TD-SCF and Hirshfeld surface to MEP analysis.

Structural and magnetic properties of polynuclear oximate copper complexes with different topologies

Two new copper(II) complexes containing the methyl(2-pyridyl)ketone oxime ligand (mpkoH) [Cu3(OH)(ClO4)2(mpko)3]·CH3OH (1) and [Cu(ClO4)(mpko)(mpkoH)]n (2) have been prepared from Cu(ClO4)2 and mpkoH in different metal-to-ligand molar ratios. In addition, the compound [Cu{(mpko)2BF2}(H2O)](BF4) (3) [(mpko)2BF2 is the fluoroboration product of the oxime] has been obtained when replacing Cu(ClO4)2 by Cu(BF4)2. Compound 1 is an isolated triangle with a {Cu3(µ3-OH)}5+ core, whereas 2 is a chain of CuII ions linked by anionic mpko− bridges. 1 exhibits strong antiferromagnetic competing interactions, as well as antisymmetric exchange. On the other hand, very weak ferromagnetic interactions are found in 2. The magnetic properties of these compounds have been analyzed by magnetic measurements and EPR spectra.

In vitro and in vivo evaluation of a 64Cu-labeled propylene amine oxime complex as a potential hypoxia imaging agent bearing two 3-nitrotriazole groups

The propylene amine oxime (PnAO) ligand, PnAO-1, 1′-bis(3-nitrotriazole) (3P3) with two 3-nitrotriazole groups was labeled with 64CuCl2. In vitro results suggest that 64Cu-3P3 can accumulate in hypoxic S180 tumor cells. Biodistribution studies of 64Cu-3P3 in mice bearing S180 tumor demonstrate that the tumor uptake, tumor-to-muscle ratio, and tumor-to-blood ratio are considerable. A tumor area could also be found in positron emission tomography imaging 18 h post-administration. For comparison, the classical hypoxia imaging agent 64Cu-ATSM was also investigated. The experimental data obtained demonstrate that 64Cu-3P3 may potentially be used as an efficient hypoxia imaging agent.

Syntheses and structures of tetraphenylantimony oximates: Ph4SbON=CHR (R = C6H4Br-2, C6H4NO2-2, C4H3S)

The reactions of pentaphenylantimony with oximes or triphenylantimony dioximates in toluene afford tetraphenylantimony oximates Ph4SbON=CHR (R = C6H4Br-2 (I), C6H4NO2-2 (II), and C4H3S-2 (III)). Triphenylantimony dioximates are synthesized by oxidative addition from triphenylantimony and oxime in diethyl ether in the presence of tert-butyl hydroperoxide. According to the X-ray diffraction data (CIF files CCDC no. 1055414 (I), 1055634 (II), and 1061727 (III)), the coordination mode of the antimony atoms in the molecules of compounds I–III is a distorted trigonal bipyramid with the oxygen atom of the oximate ligand in the axial position. The structural organization of the crystals is caused by weak hydrogen bonds.

Preparation, characterization and Microbicide activities of N'-((3-(hydroxyimino)butan-2-ylidene)-2-(phenylamino)acetohydrazide and its complexes

A series of fourteen metal complexes synthesized by reaction a new acetohydrazide oxime ligand with metal ions (CuII, NiII, CoII, MnII, FeIII, ZnII, RuIII, UO2VI and VO2VI). The Ligand, N''-((3-(hydroxyimino)butan-2-ylidene)-2-(phenylamino)acetohydrazide was prepared by refluxing equimolar amount of phenyl amino acetohydrazide with 2,3-butanedione monoxime. The synthesized compounds were characterized using elemental and thermal analyses, NMR, IR, U.V spectroscopy, magnetic and conductance measurements. The results demonstrated that complexes (2), (3), (5-7) and (10-12) were formed in 1L:1M molar ratio, while complexes (4), (8), (9), (13) and (14) were found to afford M2L formulae. The ligand acted either as a neutral bidentate, neutral, monobasic or dibasic tridentate and dibasic tetradentate ligand chelated to the metal ions via nitrogen atoms of aceto-amino and azomethine groups, carbonyl oxygen atom in its enolic or ketonic form and/or protonated or deprotonated oximino nitrogen atom, adopting aoctahedral, tetrahedral or square planar geometry around metal ions. The antimicrobial activity of the ligand as well as the metal complexes was examined using Amphotericin B and Amoxicillin as drug-standards against Aspergillum niger (A.niger) and Escherichia coli (E. coli) respectively. The ligand demonstrates a high cytotoxicity against A. niger whereas it recorded a moderate activity against E. coli. It is interestingly found that zinc(II) complex (6), copper(II) complexes (8, 10) recorded higher activities than the Amphotericin B drug with 122%, 116% and 111.1% percentages respectively against A. niger zinc(II) complex (6) was also the most sensitive complex against E. coli with (94.1 %) comparable to Amoxicillin.

Structure and properties of a new rigid tripodal oxime ligand

Synthesis and properties of a new rigid tripodal oxime ligand are reported. The ligand is a derivative of phloroglucine with three carboxime arms alternate with hydroxyl groups and three intramolecular OH⋯N hydrogen bonds. Intermolecular OH⋯O hydrogen bonds result in formation of a characteristic three-dimensional network. The structure of the compound is further analyzed and confirmed by NMR, IR and MS-techniques. DFT calculations were employed to accomplish the analysis of both the hydrogen bonding and the conformational state of the ligand under study. Additionally, the study addresses the way the conformational state and metal-replacement influence the tautomeric equilibrium OH⋯N ⇆ O−⋯+HN in the studied moieties.

Synthesis, in vitro DNA interactions, cytotoxicities, antioxidative activities, and topoisomerase inhibition potentials of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes with azo-oxime ligands

Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) transition metal complexes of 2-hydroxy-5-[(E)-(4-phenyl) diazenyl] benzaldehyde oxime and 2-hydroxy-5-[(E)-(4-nitrophenyl) diazenyl] benzaldehyde oxime ligands were synthesized and characterized through NMR, IR, ESI mass, and UV analysis. DNA binding abilities of the complexes were revealed using a UV-Vis spectrophotometer with the absorption titration and competitive binding techniques. Hydrolytic and oxidative DNA cleavage activities under different conditions were also proved. Topoisomerase I inhibition efficiencies and in vitro free radical scavenging activities of all complexes were examined. Finally, the selective cytotoxic potentials of all complexes were evaluated in human colon cancer, normal colon, and fibroblast cell lines using the water-soluble tetrazolium salt (WST-1) assay. The complexes had the ability to intercalate into stacked base pairs of DNA and topoisomerase I activity was reasonably inhibited in their presence in 0.4 mM concentrations. The abilities for scavenging of DPPH and hydroxyl radicals were found to be higher than those of known standard antioxidants (ascorbic acid, butylated hydroxyanisole, and mannitol). The results obtained from the cytotoxicity experiments are especially promising for further research, which must be carried out for the evaluation of the studied complexes as anticancer drugs.

Synthesis, structures and magnetism of heterotrimetallic Ni–Cu–Ln complexes based on a dicompartmental imine–oxime ligand

Four NiII–CuII–LnIII heterotrimetallic complexes have been prepared and structurally characterized. The Dy derivative behaves as a SMM with a small effective energy of 0.78 K under zero dc-applied field.

A Highly Active and Robust Copper-Based Electrocatalyst toward Hydrogen Evolution Reaction with Low Overpotential in Neutral Solution.

Although significant progress has been made recently, copper-based materials have long been considered to be ineffective catalysts toward the hydrogen evolution reaction (HER), in most cases, requiring high overpotentials more than 300 mV. We report here that a Cu(0)-based nanoparticle film electrodeposited in situ from a Cu(II) oxime complex can act as a highly active and robust HER electrocatalyst in neutral phosphate buffer solution. The as-prepared nanoparticle film is of poor crystallization, which incorporates significant amounts of oxime ligand residues and buffer anions PO43-. The proposed mechanism suggests that the Cu(0)-based nanoparticle film is activated with incorporated or adsorbed PO43- anions and the PO43- anions-anchored sites might serve as the actual catalytic active sites with efficient proton transport mediators. Catalysis occurs with a low onset overpotential (η) of 65 mV, and a current density of 1 mA/cm2 can be achieved with η = 120 mV. The nanoparticle film shows an excellent catalytic durability with slightly rising current density during electrolysis, presumably due to further incorporation or adsorption of PO43- anions in the process. This electrocatalyst not only forms in situ from earth-abundant materials but also operates in neutral water with low overpotential and high stability.

Half‐sandwich ruthenium, rhodium and iridium complexes featuring oxime ligands: Structural studies and preliminary investigation of in vitro and in vivo anti‐tumour activities

Half‐sandwich ruthenium, rhodium and iridium complexes (1–12) were synthesized with aldoxime (L1), ketoxime (L2) and amidoxime (L3) ligands. Ligands have the general formula [PyC(R)NOH], where R = H (L1), R = CH3 (L2) and R = NH2 (L3). Reaction of [{(arene)MCl2}2] (arene = p‐cymene, benzene, Cp*; M = Ru, Rh, Ir) with ligands L1–L3 in 1:2 metal precursor‐to‐ligand ratio yielded complexes such as [{(arene)MLκ2(N∩N)Cl}]PF6. All the ligands act as bidentate chelating nitrogen donors in κ2(N∩N) fashion while forming complexes. In vitro anti‐tumour activity of complexes 2 and 10 against HT‐29 (human colorectal cancer), BE (human colorectal cancer) and MIA PaCa‐2 (human pancreatic cancer) cell lines and non‐cancer cell line ARPE‐19 (human retinal epithelial cells) revealed a comparable activity although complex 2 demonstrated greater selectivity for MIA PaCa‐2 cells than cisplatin. Further studies demonstrated that complexes 3, 6, 9 and 12 induced significant apoptosis in Dalton's ascites lymphoma (DL) cells. In vivo anti‐tumour activity of complex 2 on DL‐bearing mice revealed a statistically significant anti‐tumour activity (P = 0.0052). Complexes 1–12 exhibit HOMO–LUMO energy gaps from 3.31 to 3.68 eV. Time‐dependent density functional theory calculations explain the nature of electronic transitions and were in good agreement with experiments.

SYNTHESIS AND CHARACTERIZATION OF (1E, 2E) - 1, 2 - DIPHENYLETHANE -1, 2 – DIENEHYDRAZONE OXIME LIGAND AND ITS Fe(II) AND Pd(II) METAL COMPLEXES.

31Aug 2016 SYNTHESIS AND CHARACTERIZATION OF (1E, 2E) - 1, 2 - DIPHENYLETHANE -1, 2 – DIENEHYDRAZONE OXIME LIGAND AND ITS Fe(II) AND Pd(II) METAL COMPLEXES. Raj R. Badekar , R. S. Lokhande , S. W. Kulkarni and R. M. Patil. Schoolof Basic Sciences, Jaipur National University, Jaipur-302017, India. Department of Chemistry, K.M.Agrawal College, Kalyan-421301, India. Department of Chemistry, Institute of Science 15, Madam Cama Road, Mumbai- 400032, India.

Oximato-bridged copper(II) compounds: syntheses, molecular structures, magnetic, thermal and spectroscopic properties

Reaction of the Schiff base, 1-(4-methylimidazol-5-yl) phenylhydrazonopropane-2-one oxime (LH), with copper(II) perchlorate hexahydrate and copper(II) nitrate trihydrate in a 1 : 1 M proportion in methanol affords [Cu2L2(H2O)(ClO4)](ClO4) (1) and [Cu2L2(H2O)2](NO3)2] (2) in moderate yields. Both 1 and 2 have been characterized by elemental analysis, ESI-MS, FT-IR, UV–vis absorption spectroscopy, EPR, electric conductivity, and magnetic susceptibility measurements. The X-ray crystal structures of 1·CH3COCH3 and 2 have been determined. Both compounds are dinuclear copper(II) complexes, with each copper μ2-bridged by two oxime ligands in a μ2-η1,η2 fashion. Variable temperature magnetic studies on 1 and 2 show that both compounds are dominated by an antiferromagnetic coupling through the oxime bridges.

Synthesis of novel tin complexes using functionalized oxime ligands

Novel tin complexes stabilized by alkoxy-functionalized oxime ligands [Sn(L1)2]2 (1) and [Sn(L2)2]2 (2), were prepared and characterized. Single-crystal X-ray diffraction analysis revealed that the complexes were obtained as dimers in which the tin metal centers are bridged by a pair of μ2-oxygen atoms. Due to the ligand steric effects, the metal centers in these complexes adopted an unusual distorted square pyramidal geometry and displayed interesting structural features. The thermo-gravimetric analyses of the complexes showed major mass loss in the 175–380°C region.

Iron(III) complexes with 2-pyridyl oxime ligands: Synthesis, structural and spectroscopic characterization, and magnetic studies

Reactions of FeIII sources with 2-pyridyl oxime ligands, pyC(R)NOH (R=H, Me, Ph), afforded the trinuclear oxo-centered complexes (NH4)[Fe3O(LH)6(H2O)3](ClO4)8 ⋅MeOH⋅1.14H2O (1⋅ MeOH⋅1.14H2O) and [Fe3O{pyC(H)NO)(PhCO2)6(H2O)]⋅MeCN (2⋅MeCN), the tetranuclear complex [Fe4(OH)4{pyC(Me)NO}4(H2O)4] (ClO4)4⋅3Me2CO⋅H2O (3⋅3Me2CO⋅H2O), and the hexanuclear complexes [Fe6(OH)6{pyC(Me)NO}6(H2O)6](ClO4)6⋅8Me2CO⋅2H2O (4⋅8Me2CO⋅2H2O), [Fe6(OH)6{pyC(Me)NO}6(MeCONH2)6](ClO4)6⋅2MeCN⋅H2O (5⋅2MeCN⋅H2O), [Fe6(OH)6 {pyC(Ph)NO}6(H2O)6](ClO4)6⋅4.4Me2CO ⋅1.6Et2O (6⋅4.4Me2CO ⋅1.6Et2O) and [Fe6(OH)6{pyC(Ph)NO}6(MeOH)6](ClO4)5.5(OH)0.5⋅MeOH⋅0.5H2O (7⋅MeOH ⋅0.5H2O), where LH is the zwitterion anionic form of 2-pyridinecarboxylic acid (picolinic acid). Complex 3 can be described as inverse 12-metallacrown-4, whereas 4–7 can be described as inverse 18-metallacrowns-6 and represent the first examples of iron(III) metallacyclic clusters with pyC(R)NOH (R=H, Me, Ph) ligands. Complexes 3 and 6 were characterized by Mossbauer spectroscopy and magnetic susceptibility measurements, while complex 2 was characterized by EPR spectroscopy.

Discrete Binuclear Cobalt(III) Bis-dioximates with Wheel-and-Axle Topology as Building Blocks To Afford Porous Supramolecular Metal–Organic Frameworks

Three binuclear and one mononuclear cobalt(III) dioximates with the compositions [Co2(dmgH)4(bpy)Cl2]·1.5dmf (1), [Co2(nioxH)4(bpy)Cl2]·0.5H2O (2), [Co2(dmgH)4(bpe)Cl2]·0.5H2O (3), and [Co(dmgH)2(bpy)Cl]·H2O (4) (where dmgH2 = dimethylglyoxime, nioxH2 = 1,2-cyclohexanedionedioxime, bpy = 4,4′-bipyridine, bpe = 1,2-bis(4-pyridyl)ethane, and dmf = N,N-dimethylformamide) were prepared by replacement of water molecule in Co(III) mononuclear dioximates by bpy and bpe ligands. All compounds were characterized by single-crystal X-ray diffraction and spectroscopic techniques. In all complexes Co(III) atoms have an identical octahedral N5Cl environment formulated by four nitrogen atoms of two mono-deprotonated oxime ligands in a square planar mode, and the nitrogen atom of the bpy/bpe molecules and chloride atom in the axial positions. In 1–3 bpy/bpe exobidentate spacer ligands serve as bridging “rods” and unite two planar cobalt(III) bis-dioximates in binuclear complex with wheel-and-axle topology. The packing of...

Synthesis of novel chiral heterometallic terpene oximates: unusual generation of an aluminium enolate by a cooperative effect.

Al-K heterometallic terpene oximate derivatives with uncommon structural features are reported. These species react with an aryl ketone leading to heterometallic enolates via an unusual route. Isolation of a remarkable heterometallic Al-K enolate confirms the cooperative mechanism proposed by DFT calculations, where the oximate ligand has a prominent role. From these enolates the formation of new C-C bonds is straightforward.

Synthesis of a novel trinuclear palladium complex: the influence of an oxime chelate ligand on biological evaluation towards double-strand DNA, BSA protein and molecular modeling studies

Synthesis of a novel cluster palladium complex containing an oxime ligand. Study of the ability of the complex to interact with DNA via groove mechanism. The molecular docking indicates high binding affinity between DNA and BSA with the Pd complex.

In vitro and in vivo evaluation of technetium-99m-labeled propylene amine oxime complexes containing nitroimidazole and nitrotriazole groups as hypoxia markers.

Hypoxia markers have been the subject of intensive research in radiopharmaceuticals, but there is little work on markers with multi-redox centers. It is necessary to further develop and investigate the compounds containing multi-redox centers systematically. Two propylene amine oxime ligands, compound 1, containing 3-nitro-1,2,4-triazole and 4-nitroimidazole and compound 2, containing 3-nitro-1,2,4-triazole and 2-nitroimidazole were synthesized and radiolabeled with (99m) Tc; then these complexes were also evaluated in vitro and in vivo. Some comparisons were made with the other complexes of our previous work, and some interesting conclusions were obtained. (99m) Tc-1 and (99m) Tc-2 displayed significant hypoxic/normoxic differentials in both S180 and H22 cell lines. These complexes held moderate tumor-to-blood and tumor-to-muscle ratios, indicating they might serve as novel hypoxia markers. Some comparisons showed the in vitro evaluation may be connected with the number and the type of the redox centers, and the biodistribution experiments may have relation with the hydrophilicity and the type of redox centers.

Solvent Extraction of Copper: An Extractive Metallurgy Exercise for Undergraduate Teaching Laboratories

A multidisciplinary experiment for advanced undergraduate students has been developed in the context of extractive metallurgy. The experiment serves as a model of an important modern industrial process that combines aspects of organic/inorganic synthesis and analysis. Students are tasked to prepare a salicylaldoxime ligand and samples of the corresponding copper and nickel complexes, before performing test extractions and UV–vis spectroscopic analysis. The oxime ligand demonstrates a clear preference for extraction of Cu2+ in the presence of Ni2+ from aqueous solution under the conditions described. It is also possible to demonstrate that the ligand can be recovered and reused. The experiment has successfully been employed in a final year project-based laboratory course involving small groups of students.

Structural control in Cu(II) coordination polymers through the conformational flexibility of a 2,3-dipyridyl ketone oxime ligand

Four new compounds prepared from the ligand 2,3-dipyridyl ketone oxime (L23) with varying Cu(II) salts were synthesised and structurally characterised, {[Cu(L23)(L23-H)](ClO4)}∞ (1), {[Cu(L23)(L23-H)](BF4)¼(H2O)}∞ (2), [Cu3(L23-H)2(L23′)(NO3)2OH]2(NO3)2(C3H8O)6 (3) and [Cu(L23)Cl2]∞ (4). The effects of differing counterions, as well as the rotational conformational versatility of L23, were demonstrated by the differing polymeric structures that were observed. Complex 1 and 2 both existed as 1-D polymeric chains with L23 acting as a pseudo-tetradentate ligand through an oxime–oximato bridge. Complex 1 formed a helical arrangement while 2 formed a chiral chain with both 1 and 2 exhibiting similar chiral packing. Complex 3 formed an unusual inverse–9–metallacrown–3 complex, with one of the L23 ligands in a zwitterionic form. Complex 4 was present as a simple 1-D meso-helical chain.