Synthesis, structural characterization and catalytic activity of a multifunctional enzyme mimetic oxoperoxovanadium(V) complex

The synthesis and structural characterization of a novel oxoperoxovanadium(V) complex [VO(O(2))(PAH)(phen)] containing the ligands 2-phenylacetohydroxamic acid (PAHH) and 1,10-phenanthroline (phen) has been accomplished. The oxoperoxovanadium(V) complex was found to mimic both vanadate-dependent haloperoxidase (VHPO) activity as well as nuclease activity through effective interaction with DNA. The complex is the first example of a structurally characterized stable oxoperoxovanadium(V) complex with a coordinated bi-dentate hydroximate moiety (-CONHO(-)) from 2-phenylacetohydroximate (PAH). The oxoperoxovanadium(V) complex has been used as catalyst for the peroxidative bromination reaction of some unsaturated alcohols (e.g. 4-pentene-1-ol, 1-octene-3-ol and 9-decene-1-ol) in the presence of H(2)O(2) and KBr. The catalytic products have been characterized by GC-MS analysis and spectrophotometric methods. The DNA binding of this complex has been established with CT DNA whereas the DNA cleavage was demonstrated with plasmid DNA. The interactions of the complex with DNA have been monitored by electronic absorption and fluorescence emission spectroscopy. Viscometric measurements suggest that the compound is a DNA intercalator. The nuclease activity of this complex was confirmed by gel electrophoresis studies.     

Synthesis,characterization, and catalytic activity of a polymer-supported copper(II) complex with a thiosemicarbazone ligand

A thiosemicarbazone Cu(II) complex anchored to a polystyrene framework has been synthesized and characterized by analytical and spectroscopic techniques. The complex was found to be a highly active catalyst for the oxidation of various organic substrates including alkenes and alcohols using H₂O₂ as oxidant. The reaction conditions were optimized with respect to temperature, solvent, oxidant, catalyst amount, and substrate to peroxide ratio. The heterogeneous catalyst was reused five times without significant loss of activity. A comparison between the catalytic activities of this polymer-supported Cu(II) complex and its homogeneous analogue was carried out.     

Synthesis,characterization, crystal structure and catalytic activity of amido azo palladium(II) complex

Transition Metal Chemistry - The newly designed tridentate ligand, 2-((2-aminophenyl)diazenyl)-N-benzylaniline, 1 has been synthesized by the reaction between 2,2′-diaminoazobenzene and...     

Synthesis, catalytic activity and phytotoxicity of a supported nickel(II) Schiff base complex

A supported Ni(II) complex has been synthesized and characterized by FTIR, UV–vis diffuse reflectance spectroscopy, thermogravimetric analysis and scanning electron microscopy. Its catalytic activity was evaluated for alkyne–azide coupling and benzothiazole synthesis. These reactions were found to require mild conditions, reaction times, and most importantly, could be carried out in aqueous medium. The catalyst could be easily recovered and reused five times without significant decrease in its activity. Leaching tests indicated that the catalyst is truly heterogeneous. The nickel complex was tested for its inhibition of germination of MTU 7029 seeds. Rice (MTU 7029, Oryza sativa) is a staple crop in southeast Asia.     

Synthesis, characterization, and antimicrobial activity of a novel proton salt and its Cu(II) complex

A novel proton transfer compound (H₂Ppz)(HDipic)₂ (I) obtained from 2-(piperazin-1-yl)ethanol (Ppz) and pyridine-2,6-dicarboxylic acid (H₂Dipic) and its Cu(II) complex (H₂Ppz)[Cu(Dipic)₂] · 6H₂O (II) have been prepared and characterized by elemental, spectral (¹H and ¹³C NMR, IR and Uv-Vis) and thermal analyses. Magnetic measurement and single crystal X-ray diffraction methods have also been applied for compound II. The molecular structure of II consists of one 1-(2-hydroxyethyl)piperazine-1,4-diium cation, one bis(pyridinium-2,6-dicarboxylate)Cu(II) anion and six uncoordinated water molecules. In complex II, the copper ion coordinates to two oxygen and one nitrogen atoms of two pyridine-2,6-dicarboxylate molecules forming an octahedral conformation. Furthermore, the synthesised compounds (I and II) were screened for their antimicrobial activities against Gram (?) (Escherichia coli and Pseudomonas aeruginosa) and Gram (+) (Staphylococcusaureus and Bacillus cereus). The results were reported, discussed and compared with the corresponding starting materials (H₂Dipic and Ppz).     

Synthesis,characterization, and biological activity of a Schiff-base Zn(II) complex

Preparation and crystal structure of {4-chloro-2-[(2-morpholinoethylimino)methyl]phenolato} methanolchlorozinc(II) are reported. The X-ray structure reveals highly distorted square pyramidal geometry around zinc, binding to one phenolate O and two imine N atoms of the Schiff base, one methanol and one chloride. The complex and its ligand were tested in vitro for antibacterial and cytotoxic activity with a wide range of bactericidal activity and significant cytotoxic activity.     

Synthesis,characterization, and catalytic application of a zinc(II) complex bearing a pyrazole-based ligand

The reaction between ZnCl₂ and N,N-bis[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]-1-phenylethylamine (bdmppea) affords [(bdmppea)ZnCl₂], whose structure has been determined by X-ray crystallography. The [(bdmppea)ZnEt₂] complex in situ prepared by the reaction between [bdmppea] and ZnEt₂ exhibited high activity toward the polymerization reaction of rac-lactide at room temperature. However, its activity decreased sharply with decreasing temperature. Stereospecificity of this catalyst characterized by heterotacticity (P_r) was determined by homonuclear decoupled NMR spectroscopy, which value was ∼0.58.     

Synthesis,characterization, and antimicrobial and catalytic activity of a new Schiff base and its metal(II) complexes

We presented the synthesis of a new Schiff base and its complexes properties with some transition metal ions in this study. (1-amino-2-thioxo-4-p-tolyl-1,2-dihydropyrimidin-5-yl)(p-tolyl)methanone was synthesized as the starting material, and (1-((2-hydroxynaphthalen-1-yl)methyleneamino)-2-thioxo-4-p-tolyl-1,2-dihydropyrimidin-5-yl)(p-tolyl)methanone (Hnafmmp) (1) and its Ni(II) (2), Pd(II) (3), Pt(II) (4), Cu(II) (5), Co(II) (6) complexes were prepared using above-mentioned starting material. The structures of these new compounds (ligand and its complexes) were characterized with UV–Vis, FTIR, LC–MS, ¹H NMR, ¹³C NMR, magnetic susceptibility, conductivity measurement, X-ray powder diffraction method, and thermal analyses techniques. The ¹H NMR chemical shifts of all complexes were calculated by using the gauge-invariant atomic orbital HF (3.21G) method in DMSO phases. All measured results were compared with the experimental data. The ligand and its complexes were also evaluated as antimicrobial agents against representative strains bacteria. Furthermore, we studied the catalytic activity of these compounds in Suzuki–Miyaura cross-coupling reaction in aqueous media.     

Synthesis,characterization and catalytic activity of halo-methyl-bis(salicylaldehyde)ethylenediamine cobalt(II) complexes

The synthesis, characterization and catalytic activity of a series of tetra-halo-dimethyl salen and di-halo-tetramethyl-salen ligands are reported in this paper: α,α′-dimethyl-Salen (dMeSalen) (L¹); 3,3′,5,5′-tetrachloro-α,α′-dimethyl-Salen, (tCldMeSalen) (L²); 3,3′-dibromo-5,5′-dichloro-α,α′-dimethyl-Salen, (dCldBrdMeSalen) (L³); 3,3′,5,5′-tetrabromo-α,α′-dimethyl-Salen, (tBrdMeSalen) (L⁴); 3,3′,5,5′-tetraiodo-α,α′-dimethyl-salen, (tIdMeSalen) (L⁵); 3,3′-dichloro-5,5′,α,α′-tetramethyl-Salen (dCltMeSalen) (L⁶); 3,3′-dibromo-5,5′,α,α′-tetramethyl-Salen (dBrtMeSalen) (L⁷); and 3,3′-diiodo-5,5′,α,α′-tetramethyl-Salen (dItMeSalen) (L⁸) (Salen = bis(salicylaldehyde)ethylenediamine). Upon reaction with Co(II) ions, these ligands form complexes with square planar geometry that have been characterized by elemental analysis, cyclic voltammetry, UV–Vis, IR and EPR spectroscopies. In the presence of pyridine the obtained Co(II) complexes were found able to bind reversibly O₂, which was shown by EPR spectroscopy and cyclic voltammetry. They were also found able to catalyze the oxidation of 2,6-di-tert-butylphenol (DtBuP) (9) with formation of 2,6-di-tert-butyl-1,4-benzoquinone (DtBuQ) (10) and 2,6,2′,6′-tetra-tert-butyl-1,1′-diphenobenzoquinone (TtBuDQ) (11). These properties are first influenced by the coordination of pyridine in axial position of the Co(II) ion that causes an increase of the electronic density on the cobalt ion and as a consequence a decrease in the E_1/2 value and an increase of the reducing power of the Co(II) complex. It is noteworthy that, under those conditions the complexes also show a remarkable quasi-reversible behaviour. Second, complex properties are also influenced by the substituents (methyl and halogen) grafted on the aromatic ring and on the azomethynic groups. The donating methyl substituent on the azomethynic groups causes a decrease in the E_1/2 value, whereas the halogen substituents on the aromatic rings have two effects: a mesomeric donating effect that tends to lower the redox potential of the complex, and a steric effect that tends to decrease the conjugation of the ligand and then to increase the redox potential of the Co(II) complex. In pyridine, the steric effect predominates, which causes both an increase of the redox potential and a decrease of the selectivity of the oxidation of phenol 9. As a result of all these effects, it then appears that the best catalysts to realize the selective oxidation of 2,6-di-tert-butyl-phenol (9) by O₂ are the Co complexes of ligands bearing CH₃ donating substituents, Co(dMeSalen) 1 (2CH₃ substituents), and Co-di-halo-tetra-methyl-salen complexes 6, 7 and 8 (4CH₃ substituents), in the presence of pyridine.     

Synthesis,X‐ray structure,characterization and catalytic activity of a polymeric manganese(II) complex with iminodiacetate

A polymeric manganese(II) complex with the general formula [Mn(O₂CCH₂NH₂CH₂CO₂)₂(H₂O)₂]_n from reaction of iminodiacetatic acid and manganese(II) perchlorate under nitrogen in water, was synthesized and characterized. The structure of the complex was determined using single‐crystal X‐ray diffraction, elemental analysis, IR and UV‐vis spectra. This complex exhibited excellent catalytic activity and selectivity for oxidation of various alcohols and sulfides to the corresponding aldehydes/ketone and sulfoxides using urea hydrogen peroxide and oxone (2KHSO₅·KHSO₄·K₂SO₄), respectively, as oxidants under air at room temperature. The easy preparation, mild reaction conditions, high yields of the products, short reaction time, no over‐oxidation products, high selectivity and inexpensive system make this catalytic system a useful method for oxidizing various alcohols and sulfides. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and characterization of a polymer-anchored palladium(II) Schiff base complex and its catalytic efficiency in phosphine-free Sonogashira coupling reactions

A polymer-anchored Pd(II) Schiff base complex has been synthesized by reacting a polymeric amine with 2-pyridinecarboxaldehyde to get the polymer-anchored Schiff base, which was then reacted with palladium acetate. The catalyst was characterized by physicochemical and spectroscopic methods. It shows excellent catalytic activity in the Sonogashira coupling of phenylacetylene with aryl halides using triethylamine as a base and copper iodide as a co-catalyst in water under open air at 70 °C. We have also studied the effects of base and solvent on the coupling reaction. Sonogashira reactions of phenylacetylene with a variety of functionalized aryl halides were performed under the optimized reaction conditions. This catalyst gives excellent yields without the use of phosphine ligands. Further experiments showed that the catalyst can be used five times without much loss in the catalytic activity.     

Synthesis,characterization, spectroscopic study,and catalytic behavior of ruthenium(II) o-phenanthroline complex with dipicolinate

A new dipicolinate complex of Ru(II), cis-[Ru(phen)₂dipic]?·?9.5H₂O (1), where dipic is dipicolinate or pyridine-2,6-dicarboxylate and phen is 1,10-phenanthroline, has been synthesized and characterized by elemental analysis, spectroscopic (IR, UV-Vis), cyclic voltammetry, and single-crystal X-ray diffraction. ORTEP drawing of cis-[Ru(phen)₂dipic]?·?9.5H₂O shows that the coordination geometry around Ru(II) is a distorted octahedron. It crystallizes in the triclinic system, with space group P 1, a?=?10.4633(2)?Å, b?=?13.6332(4)?Å, c?=?13.6637(4)?Å, α?=?67.516(3)°, β?=?69.757(2)°, γ?=?77.201(2)°, V?=?1680.74(8)?ų, Z?=?2, and R _int?=?0.0311. In 1, two phen are bidentate N,N′ ligands. The Ru(II) in 1 is bonded to dipicolinate through pyridine nitrogen and one oxygen of carboxylate groups, thus pyridine-2,6-dicarboxylate is a bidentate N,O ligand. Efficient and selective oxidation of alcohols with NaIO₄ as oxidant was conducted by this complex catalyst in CH₃OH/H₂O as solvents under air at room temperature.     

Synthesis,characterization, and antibacterial activity of a manganese(II) complex of triaryltriazole

A manganese(II) complex of 4-(4-methylphenyl)-3,5-bis(2-pyridyl)-4H-1,2,4-triazole (MBPT) was synthesized and characterized by X-ray crystallography. [Mn(MBPT)₂(H₂O)₂](ClO₄)₂?·?4H₂O is a divalent mononuclear manganese(II) complex with manganese coordinated to four nitrogens from two triazole ligands and two oxygens from two water molecules in a slightly distorted octahedral geometry. The complex and ligand were tested in vitro for their antibacterial activities. The title complex showed a wide range of bactericidal activities.     

Synthesis,characterization and catalytic activity of Rh (PPh3)2 (en)Cl complex

Ethylenediamine bis(triphenylphosphine) monochlororhodium has been prepared by the interaction of Wilkinson's catalyst and ethylenediamine in benzene. The complex has been isolated and characterized by conventional and spectroscopic methods. The catalytic activity of the complex was investigated for the hydrogenation of 1-octene as a model reaction at a hydrogen pressure of 1 atmosphere (101 kPa) using methanol as a solvent. The influence of various factors such as catalyst, substrate concentrations and temperature have been studied. The hydrido complex has been identified as an intermediate product by IR and NMR studies. The experimental data are in accordance with a rate expression of the form: .     

Synthesis and characterization of (pyrazolylethylphosphinite)nickel(II) complexes and catalytic activity towards ethylene oligomerization

Compounds (2‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)ethyldiphenylphosphinite ( L1 ), 2‐(3,5‐di‐tert‐butyl‐1H‐pyrazol‐1‐yl)ethyldiphenylphosphinite ( L2 ) , and 2‐(3,5‐diphenyl‐1H‐pyrazol‐1‐yl)ethyldiphenylphosphinite ( L3 ) were prepared using the synthetic routes reported in literature. These compounds were reacted with [NiCl₂(DME)₂] or [NiBr₂(DME)₂] under appropriate reaction conditions to afford six new nickel(II) compounds ([NiCl₂( L1)] ( 1 ), [NiCl₂( L2 )] ( 2 ), [NiCl₂( L3 )] ( 3 ), [NiBr₂( L1 )] ( 4 ), [NiBr₂( L2 )] ( 5 ) and [NiBr₂( L3 )] ( 6 )). The new nickel(II) pre‐catalysts catalyze the oligomerization of ethylene, in the presence of ethylaluminium dichloride as co‐catalyst, to produce butenes, hexenes, octenes and higher carbon chain ethylene oligomers with very little Friedel‐Crafts alkylation products when the reactions were run in toluene.     

Reactivity and catalytic activity of a robust ruthenium(II)-triphos complex

The ruthenium(II)-triphos acetato complex [RuCl(OAc)(kappa3-triphos)] (triphos = (PPh2CH2)3CMe) has been found to be an active catalyst precursor for the hydrogenation of 1-alkenes under relatively mild conditions (5-50 bar H2, 50 degrees C). In contrast to related triphenylphosphine complexes, [RuCl(OAc)(kappa3-triphos)] is much less air sensitive and high catalytic activities were achieved when catalyst samples were prepared without exclusion of air or moisture. Substitution of the acetato ligand can be effected by treatment of acid, affording [Ru2(mu-Cl)3(kappa3-triphos)2]Cl and [RuCl(kappa3-triphos)]2(BF4)2 with aqueous HCl and [Et2OH]BF4, respectively, or by heating with dmpm in the presence of [NH4]PF6, resulting in formation of [RuCl(kappa2-dmpm)(kappa3-triphos)]PF6 (dmpm = PMe2CH2PMe2). A hydride complex, [RuHCl(kappa3-triphos)], formed by acetato-mediated heterolytic cleavage of dihydrogen is proposed as the active catalytic species. An inner-sphere, monohydride mechanism is suggested for the catalytic cycle, with chloro and triphos ligands playing a spectator role. These mechanistic proposals are consistent with reactivity studies carried out on [RuCl(OAc)(kappa3-triphos)] and [RuH(OAc)(kappa3-triphos)] and supported by a computational analysis. The solid-state structures of [RuCl(OAc)(kappa3-triphos)], [RuCl(kappa3-triphos)]2(BF4)2, and [RuCl(kappa2-dmpm)(kappa3-triphos)]PF6 have been established by X-ray diffraction.     

Synthesis in solvent-free conditions,characterization and biological activity of a new Schiff-base ligand and its Cu(II) complex

A new bis-imine Schiff base (N₈O₂ donor, LH₂) has been synthesized by melt condensation of 3-amino-1,2,4-triazole with 1,5-bis(2′-formylphenyl)-1,5-dioksapentane in 2 : 1 molar ratio, in solvent and solvent-free conditions. The ligand has been characterized using FTIR, UV–Vis, ¹H NMR, ¹³C NMR, mass spectra, elemental analysis, and thermal (TGA-DSC) techniques. A new complex of LH₂ with Cu(II) has been synthesized in solvent and solvent-free conditions. FTIR, UV–Vis mass spectra, and thermal analysis (TGA-DSC) have been used to characterize the Cu(II) complex. Thermal degradation showed that the final products were black carbon and metallic copper. Distorted octahedral geometry has been observed around CuLH₂Cl₂ · LH₂ and its Cu(II) complex have been screened for in vitro antifungal and antioxidant activities. Antioxidation was determined for their superoxide scavenging and reducing activities. The ligand and its Cu(II) complex have strong antifungal activity against Aspergillus niger. The compounds have significant superoxide anion radical scavenging activity and reducing power against various antioxidant systems in vitro.     

Synthesis and characterization of a platinum(II) complex with N-acetyl-L-cysteine

Synthesis and spectroscopic studies in the solid-state of a platinum(II) complex with N-acetyl-L-cysteine are described. Elemental analyses are consistent with composition Pt₂(C₅H₈NO₃S)₄ · 3H₂O. Solid-state ¹³C NMR, infrared, and U-Vis spectroscopic results are consistent with coordination of the ligand to platinum(II) through sulfur. Thermal analyses confirmed water in the complex composition. Final residue of the thermal treatment was identified by powder X-ray diffractometry as metallic platinum.     

Synthesis, characterization and catalytic activity of organolanthanide(II) complexes with heterocyclic-functionalized fluorenyl ligands

Two series of new organolanthanide(II) complexes with tetrahydro-2H-pyranyl- or N-piperidineethyl-functionalized fluorenyl ligands were synthesized via one-electron reductive elimination reaction. Treatments of [(Me₃Si)₂N]₃Ln^III(μ-Cl)Li(THF)₃ with 2 equiv. of C₅H₉OCH₂C₁₃H₉ (1) or C₅H₁₀NCH₂CH₂C₁₃H₉ (2), respectively, in toluene at about 80 °C produced, after workup, the corresponding organolanthanide(II) complexes with formula [η⁵:η¹-C₅H₉OCH₂C₁₃H₈]₂Ln^II (Ln = Yb (3), Ln = Eu (4)) and [η⁵:η¹-C₅H₁₀NCH₂CH₂C₁₃H₈]₂Ln^II (Ln = Yb (5), Ln = Eu (6)) in good yields. All the compounds were fully characterized by spectroscopic methods and elemental analyses. The structures of complexes 3, 4, and 6 were additionally determined by single-crystal X-ray analyses. It represents the first example of solvent-free organolanthanide(II) complexes with fluorenyl ligands. The catalytic properties of the organolanthanide(II) complexes on the polymerization of ε-caprolactone and methyl methacrylate have been studied. The temperatures, solvents and coordination effects on the catalytic activities of the complexes were examined.     

Synthesis,characterization, and catalytic properties of a cobalt(II) complex supported by an amine-bis(phenolate) ligand

A cobalt(II) complex [L′CoPy] 1 was prepared by the reaction of dimethylaminoethylamino-N,N-bis(2,4-dibromo)phenol (H₂L′) with CoCl₂. Electrochemical studies indicate that this complex is among the most efficient homogeneous catalysts for water reduction, with a turnover frequency of 917.7 mol of hydrogen per mole of catalyst per hour at an overpotential of 636.7 mV (pH 7.0). Additionally, under photoirradiation with blue light (λ _max = 469 nm), complex 1 in combination with [Ru(bpy)₃]Cl₂ and ascorbic acid (pH 4.0 in aqueous solution) also produces hydrogen with a turnover number of 4.9 × 10⁵ mol of H₂ per mol of catalyst.