Polymer Supported Schiff Base Complexes of Iron(III), Cobalt(II) and Nickel(II) Ions and their Catalytic Activity in Oxidation of Phenol and Cyclohexene

The polymer supported transition metal complexes of N,N′‐bis (o‐hydroxy acetophenone) hydrazine (HPHZ) Schiff base were prepared by immobilization of N,N′‐bis(4‐amino‐o‐hydroxyacetophenone)hydrazine (AHPHZ) Schiff base on chloromethylated polystyrene beads of a constant degree of crosslinking and then loading iron(III), cobalt(II) and nickel(II) ions in methanol. The complexation of polymer anchored HPHZ Schiff base with iron(III), cobalt(II) and nickel(II) ions was 83.30%, 84.20% and 87.80%, respectively, whereas with unsupported HPHZ Schiff base, the complexation of these metal ions was 80.3%, 79.90% and 85.63%. The unsupported and polymer supported metal complexes were characterized for their structures using I.R, UV and elemental analysis. The iron(III) complexes of HPHZ Schiff base were octahedral in geometry, whereas cobalt(II) and nickel(II) complexes showed square planar structures as supported by UV and magnetic measurements. The thermogravimetric analysis (TGA) of HPHZ Schiff base and its metal complexes was used to analyze the variation in thermal stability of HPHZ Schiff base on complexation with metal ions. The HPHZ Schiff base showed a weight loss of 58% at 500°C, but its iron(III), cobalt(II) and nickel(II) ions complexes have shown a weight loss of 30%, 52% and 45% at same temperature. The catalytic activity of metal complexes was tested by studying the oxidation of phenol and epoxidation of cyclohexene in presence of hydrogen peroxide as an oxidant. The supported HPHZ Schiff base complexes of iron(III) ions showed 64.0% conversion for phenol and 81.3% conversion for cyclohexene at a molar ratio of 1∶1∶1 of substrate to catalyst and hydrogen peroxide, but unsupported complexes of iron(III) ions showed 55.5% conversion for phenol and 66.4% conversion for cyclohexene at 1∶1∶1 molar ratio of substrate to catalyst and hydrogen peroxide. The product selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was 90.5% and 96.5% with supported HPHZ Schiff base complexes of iron(III) ions, but was found to be low with cobalt(II) and nickel(II) ions complexes of Schiff base. The selectivity for catechol (CTL) and epoxy cyclohexane (ECH) was different with studied metal ions and varied with molar ratio of metal ions in the reaction mixture. The selectivity was constant on varying the molar ratio of hydrogen peroxide and substrate. The energy of activation for epoxidation of cyclohexene and phenol conversion in presence of polymer supported HPHZ Schiff base complexes of iron(III) ions was 8.9 kJ mol^?1 and 22.8 kJ mol^?1, respectively, but was high with Schiff base complexes of cobalt(II) and nickel(II) ions and with unsupported Schiff base complexes.     

Preparation and catalysis of chloromethylated polystyrene‐supported macrocyclic Schiff base metal complexes for the oxidation of cumene

Chloromethylated polystyrene‐supported macrocyclic Schiff base metal complexes (PS‐L‐M, M = Cu²⁺, Co²⁺, Ni²⁺, and Mn²⁺) were synthesized and characterized by the methods of IR, ICP, and small area X‐ray photoelectron spectroscopy (XPS). The oxidation of cumene by molecular oxygen in the absence of solvent with the synthesized complexes employed as catalyst was carried out. In comparison with their catalytic activities, PS‐L‐Cu is a more effective catalyst for the oxidation of cumene. The main products are 2‐phenyl‐2‐propanol (PP) and cumene hydroperoxide, which were measured by GC/MS. The influences of reaction temperature, the amount of catalyst, as well as the reaction time on the oxidation of cumene were investigated. Copyright © 2008 John Wiley & Sons, Ltd.     

Dinuclear metal complexes of Schiff base ligands as catalysts for oxidation and epoxidation reactions

Dinuclear copper(II) complexes (Cu₂ L_nCl₃), nickel(II) complexes (Ni₂ L_nCl₃) and cobalt(II) complexes (Co₂L ₂ ⁿ Cl₂) from Schiff base ligands are synthesised, characterised and used as catalysts for oxidation of 3,5-DTBC to 3,5-DTBQ. (Cu₂L_nCl₃) are found to be more efficient than the other complexes. Dinuclear iron(III) complexes of composition (Fe₂L₂Cl₂) and ruthenium (III) complexes of composition Ru₂L ₂ ⁿ Cl₆(PPh₃)₂ and Ru₂L ₂ ⁿ Cl₂(PPh₃)₂ catalyse epoxidation of styrene and cyclohexene. Catalytic activities of ruthenium(III) complexes are much greater than those of analogous iron(III) complexes.     

Catalytic wet peroxide oxidation of phenol over AlFe-pillared montmorillonite

Catalytic wet peroxide oxidation of phenol over AlFe-pillared montmorillonite was carried out at room temperature, in a glass batch reactor, under constant airflow at day and UV light, alternatively. At higher concentration of phenol in water solution the efficiency of heterogeneous pillared clay catalyst was significantly lower than the efficiency of homogeneous iron catalyst. This revised version was published online in June 2006 with corrections to the Cover Date.     

Half‐sandwich Ir (III) and Rh (III) complexes as catalysts for water oxidation with double‐site

A series of neutral binuclear iridium and rhodium complexes were synthesized based on bis‐imine ligands under mild conditions. These half‐sandwich late transition metal complexes were isolated in good yields and characterized by elemental analysis, ¹H NMR, ¹³C NMR, HR‐MS, and FT‐IR spectroscopies, and the solid state structure of complexes 1 and 2 were further confirmed by single‐crystal X‐ray diffraction. Cyclic voltammetry (CV) characterization indicated that the complex 1 has the best catalyst for water oxidation process with TOF of 0.8 s^?1 at low overpotential of 0.325 V in methanol‐phosphate buffer. The proposed double‐site water oxidation mechanism had been also speculated .     

Ruthenium carbonyl complexes in catalytic epoxidation of olefins co‐catalyzed by isobutyl‐aldehyde

The present work shows the catalytic activity of a series of carbonyl ruthenium complexes in the epoxidation of olefins co‐catalyzed by isobutyl‐aldehyde. The complexes display catalytic activity in the epoxidation of the cyclohexene with high selectivity. Copyright © 2006 John Wiley & Sons, Ltd.     

Polymer supported catalysts for oxidation of phenol and cyclohexene using hydrogen peroxide as oxidant

Polymer supported transition metal complexes of N,N′-bis (o-hydroxy acetophenone) hydrazine (HPHZ) Schiff base were prepared by anchoring its amino derivative Schiff base (AHPHZ) on cross-linked (6 wt%) polymer beads and then loading iron(III), copper(II) and zinc(II) ions in methanol. The loading of HPHZ Schiff base on polymer beads was 3.436 mmol g⁻¹ and efficiency of complexation of polymer anchored HPHZ Schiff base for iron(III), copper(II) and zinc(II) ions was 83.21, 83.40 and 83.17%, respectively. The efficiency of complexation of unsupported HPHZ Schiff base for these metal ions was lower than polymer supported HPHZ Schiff base. The structural information obtained by spectral, magnetic and elemental analysis has suggested octahedral and square planar geometry for iron(III) and copper(II) ions complexes, respectively, with paramagnetic behavior, but zinc(II) ions complexes were tetrahedral in shape with diamagnetic behavior. The complexation with metal ions has increased thermal stability of polymer anchored HPHZ Schiff base. The catalytic activity of unsupported and polymer supported HPHZ Schiff base complexes of metal ions was evaluated by studying the oxidation of phenol (Ph) and epoxidation of cyclohexene (CH). The polymer supported metal complexes showed better catalytic activity than unsupported metal complexes. The catalytic activity of metal complexes was optimum at a molar ratio of 1:1:1 of substrate to oxidant and catalyst. The selectivity for catechol (CTL) and epoxy cyclohexane (ECH) in oxidation of phenol and epoxidation of cyclohexene was better with polymer supported metal complexes in comparison to unsupported metal complexes. The energy of activation for oxidation of phenol (22.8 kJ mol⁻¹) and epoxidation of cyclohexene (8.9 kJ mol⁻¹) was lowest with polymer supported complexes of iron(III) ions than polymer supported Schiff base complexes of copper(II) and zinc(II) ions.     

Nano‐sized metal complexes of azo L‐histidine: Synthesis,characterization and their application for catalytic oxidation of 2‐amino phenol

A novel azo dye ligand formed by the coupling of L‐histidine with 2‐hydroxy‐1‐naphthaldyhide(H₂L) and its Ru³⁺, Pd²⁺ and Ni²⁺ nano‐sized complexes were obtained and described by elemental analysis, TGA, magnetic moment measurements, molar conductance, UV‐Vis, ESR, X‐ray powder diffraction, IR, SEM, TEM, ¹H‐nmr, ¹³C‐nmr, and EI‐mass spectral studies. The analytical results and spectral studies detected that the H₂L ligand acts as dibasic tetradentate via aldehyde oxygen, azo nitrogen and deprotonated OH and COOH groups. The data showed the paramagnetic Ru³⁺ complex has octahedral geometry while Pd²⁺ and Ni²⁺ have square planar structures. The molar conductance measurements display all complexes are nonelectrolyte. The crystallinity, morphology and average particle size data revealed the prepared complexes were formed in the Nano scale. The average particle size as calculated from TEM images are found to be 13.72, 64.52 and 115.00 nm for Ru³⁺, Pd²⁺ and Ni²⁺ chelates, respectively. The catalytic activities of these compounds were checked for oxidation of 2‐amino phenol to 2‐amino‐3H phenoxazine‐3‐one as heterogeneous catalysts. A 96, 31 and 21% catalytic conversion are found when using Ru(III), Pd(II) and Ni(II) complexes respectively.     

New anti‐bacterial polychelates: synthesis,characterization, and anti‐bacterial activities of thiosemicarbazide–formaldehyde resin and its polymer–metal complexes

New polymeric ligand (resin) was prepared by the condensation of thiosemicarbazides with formaldehyde in the presence of acidic medium. Thisemicarbazide–formaldehyde polymer–metal complexes were prepared with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) in 1:2 metal:ligand molar ratio. The polymeric ligand and its polymer–metal complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), FTIR, ¹³C NMR and ¹H NMR. The geometry of central metal ions was conformed by electronic (UV–vis) and EPR spectra. The antibacterial activities of all the synthesized polymers were investigated against Bacillus subtilis and Staphylococcus aureus (Gram‐positive) and Escherichia coli and Salmonella typhi (Gram‐negative). These compounds showed excellent activities against these bacteria using the shaking flask method. Copyright © 2008 John Wiley & Sons, Ltd.     

金属担载量对CuO/AC干法催化氧化苯酚的影响

采用程序升温氧化（TPO）技术和吸附 催化氧化循环实验,研究了金属担载量对CuO/AC催化-吸附剂干法催化氧化苯酚的影响。结果表明,随着金属担载量的增加,CuO/AC催化-吸附剂的苯酚催化氧化活性升高,并且苯酚与催化-吸附剂之间的相互作用增强,使吸附的苯酚不易脱附/降解脱附。同时,CuO/AC催化 吸附剂自身的烧蚀活性也随金属担载量的增加而升高。对于吸附-干法催化氧化法而言,CuO/AC存在一个较佳的金属担载量范围,该范围以Cu的质量分数计为3%～5%。     

Homogeneous mono-and bimetallic catalysts for the oxidation of cyclohexene

In the absence of solvent, the first-row transition-metal acetylacetonate complexes and RuCl₂(PPh₃)₃ give fairly high turnovers for the allylic oxidation of cyclohexene under atmospheric pressure of oxygen. Synergetic effect is observed for the oxidation of cyclohexene by using M(acac)_n−RuCl₂(PPh₃)₃ bimetallic catalysts.     

Decontamination of heavy metal complexes by advanced oxidation processes: A review

Heavy metal complexes with high mobility are widely distributed in wastewater from modern industries, which are more stable and refractory than free heavy metal ions. Their removals from wastewater draw increasing attentions and various technologies have been developed, among which advanced oxidation processes (AOPs) are more effectively and promising. Progresses on five representative types of AOPs, including Fenton (like) oxidation, electrochemical oxidation, photocatalytic oxidation, ozonation and discharge plasma oxidation for heavy metal complexes degradation are summarized in this review. Their rationales, advantages, applications, challenges and prospects are introduced independently. Combinations among these AOPs, such as electrochemical Fenton oxidation and photoelectrocatalytic oxidation, are also comprehensively highlighted. Future efforts should be made to reduce acid requirement and scale up for practical applications of AOPs for heavy metal complex degradation efficiently and cost-effectively.     

异羟肟酸过渡金属配合物对对氯甲苯催化氧化性能的研究

考察了N-羟基-N-苯基苯甲酰胺的钴、锰和铜配合物在对氯甲苯液相氧化生成对氯苯甲酸反应中的催化性能.考察了反应温度、催化剂浓度、中心金属离子、以及助催化剂对催化氧化反应的影响,发现以钴配合物为催化剂,反应温度为140℃,催化剂浓度为1.0 × 10-3 mol·L-1为最佳反应条件.添加NaBr和四甘醇能促进对氯甲苯的...     

Polymer‐supported metal complexes as antibacterial agents: synthesis,characterization and thermal degradation kinetics

Polymeric metal complexes were prepared using a synthesized novel terpolymer ligand involving anthranilic acid–o‐toluidine–formaldehyde by a polycondensation technique. The synthesized ligand and its metal complexes were characterized using elemental analysis and molar conductivity measurements, and FT‐IR, electronic, electron spin resonance and NMR (¹H and ¹³C) spectral methods. The surface morphology and the nature of the synthesized compounds were examined using scanning electron microscopy and X‐ray diffraction. The thermal stabilities of the ligand and its metal complexes were determined using thermogravimetric analysis (TGA). From the TGA results, various kinetic parameters, i.e. activation energy and order of reaction, and thermodynamic parameters, i.e. entropy change, apparent entropy, frequency factor and free energy change, were determined using the Freeman–Carroll and Sharp–Wentworth methods. In addition, a thermal degradation model was also proposed using the Phadnis–Deshpande method. The thermal stability of the ligand and its metal complexes was found to be appreciably high; in particular, the ligand showed very high stability compared to its metal complexes due to intramolecular hydrogen bonding. Furthermore, the synthesized compounds were subjected to in vitro antibacterial studies with various microorganisms. The results of the studies confirmed that the compounds showed better antibacterial results than a standard antibacterial drug. Copyright © 2014 John Wiley & Sons, Ltd.     

The metal complexes of new Schiff bases containing phosphonate groups and catalytic properties for alkane oxidation

In this study, two new salicylidene phosphonate ligands (HL¹ and HL²) and their metal complexes (Cu²⁺, VO²⁺ and La³⁺) were synthesized and characterized by spectroscopic and analytical methods. The molecular structure of the ligand HL¹ was determined by single‐crystal X‐ray diffraction study. In the structure of the ligand, there is an intramolecular phenol‐imine hydrogen bond. The synthesized compounds exhibit only one emission maximum upon excitation at 270–295  nm range. Complexation of the Schiff base ligands with metal ions did not cause a considerable quenching effect. Finally, the complexes prepared were used as catalysts in cyclohexane oxidation under microwave irradiation. The complexes showed high conversion rates (> 90%) for cyclohexane oxidation; however, poor selectivity was observed for all complexes. The La³⁺ complexes showed better selectivity for cyclohexane → cyclohexanol transformation with about 45% selectivity.     

Cu-Ce/AC吸附-催化剂对所吸附苯酚的催化氧化行为的研究

对活性炭载氧化铜和氧化铈（Cu-Ce/AC）吸附 催化剂在连续吸附-催化氧化苯酚循环过程中的催化氧化活性和失活原因进行了研究。结果表明,Cu-Ce/AC的苯酚吸附性能和催化氧化活性随着吸附 催化氧化循环次数的增加而逐渐降低,经5次循环后,苯酚的初始氧化温度提高约25℃。通过对使用过的Cu Ce/ACs进行XPS、ICP分析, 发现Ce和Cu的流失较小,苯酚残留物覆盖表面Ce和Cu是苯酚催化氧化活性降低的主要原因,残留物主要含有C-O-C和C-OH等官能团。     

Synthesis,characterization and catalytic activity of peripherally tetra‐substituted Co(II) phthalocyanines for cyclohexene oxidation

New 3,3‐diphenylpropoxyphthalonitrile (5) was obtained from 3,3‐diphenylpropanol (3) and 4‐nitrophthalonitrile (4) with K₂CO₃ in DMF at 50 °C. The novel cobalt(II) phthalocyanine complexes, tetrakis‐[2‐(1,4‐dioxa‐8‐azaspiro[4.5]dec‐8‐yl)ethoxy] phthalocyaninato cobalt(II) (2) and tetrakis‐(3,3‐diphenylpropoxy)phthalocyaninato cobalt(II) (6) were prepared by the reaction of the phthalonitrile derivatives 1 and 5 with CoCl₂ by microwave irradiation in 2‐(dimethylamino)ethanol for at 175 °C, 350 W for 7 and 10 min, respectively. These new cobalt(II)phthalocyanine complexes were characterized by spectroscopic methods (IR, UV–visible and mass spectroscopy) as well as elemental analysis. Complexes 2 and 6 are employed as catalyst for the oxidation of cyclohexene using tert‐butyl hydroperoxide (TBHP), m‐chloroperoxybenzoic acid (m‐CPBA), aerobic oxygen and hydrogen peroxide (H₂O₂) as oxidant. It is observed that both complexes can selectively oxidize cyclohexene to give 2‐cyclohexene‐1‐ol as major product, and 2‐cyclohexen‐1‐one and cyclohexene oxide as minor products. TBHP was found to be the best oxidant since minimal destruction of the catalyst, higher selectivity and conversion were observed in the products. Copyright © 2012 John Wiley & Sons, Ltd.     

The catalytic role of transition metal salts on supercritical water oxidation of phenol and chlorophenols in a titanium reactor

The oxidation of phenol and some chlorophenols by molecular oxygen at a concentration of 1.5x10^-4 mol dm^-3 has been studied in a small static titanium tubular reactor at temperatures of 648, 657, 673 K and a pressures of 22 MPa. The effect of transition metal salts (CuSO₄, VSO₄, FeSO₄, MnSO₄, NiSO₄, CoSO₄), added in small environmentally acceptable amounts as homogeneous catalysts, was also studied, with copper showing a good catalytic effect. This revised version was published online in June 2006 with corrections to the Cover Date.     

In vitro antibacterial and antifungal assay of poly‐(ethylene oxamide‐N,N′‐diacetate) and its polymer–metal complexes

A new polyester, poly‐(ethylene oxamide‐N,N′‐diacetate) (PEODA), containing glycine moiety was synthesized by the reaction of oxamide‐N,N′‐diacetic acid and ethylene glycol and its polymer–metal complexes were synthesized with transition metal ions. The monomer oxamide‐N,N′‐diacetic acid was prepared by the reaction of glycine and diethyl oxalate. The polymer and its metal complexes were characterized by elemental analysis and other spectroscopic techniques. The in vitro antibacterial activities of all the synthesized polymers were investigated against some bacteria and fungi. The analytical data revealed that the coordination polymers of Mn(II), Co(II) and Ni(II) are coordinated with two water molecules, which are further supported by FTIR spectra and TGA data. The polymer–metal complexes showed excellent antibacterial activities against both types of microorganisms; the polymeric ligand was also found to be effective but less so than the polymer–metal complexes. On the basis of the antimicrobial behavior, these polymers may be used as antifungal and antifouling coating materials in fields like life‐saving medical devices and the bottoms of ships. Copyright © 2007 John Wiley & Sons, Ltd.