Selective Oxidation of Cyclohexene, Toluene and Ethyl Benzene Catalyzed by Bis-(L-tyrosinato)copper(II), Immersed in a Magnetite-Infused Silica Matrix

Bis-(L-tyrosinato)copper(II) was reacted with 3-(chloropropyl)-trimethoxysilane functionalized silica that has infused magnetite to yield a magnetically separable catalyst in which the copper carboxylate is covalently linked to the silica matrix through the silane linkage. The immobilized catalyst has been characterized by spectroscopic studies (such as FT-IR, EPR, Magnetic Measurement, SEM) and chemical analyses. The immobilized catalytic system functions as an efficient heterogeneous catalyst for oxidation of cyclohexene, toluene and ethyl benzene in the presence of hydrogen peroxide (as an oxidant) and sodium bicarbonate (a co-catalyst). The reaction conditions have been optimized for solvent, temperature and amount of oxidant and catalyst. Comparison of the encapsulated catalyst with the corresponding homogeneous catalyst showed that the heterogeneous catalyst had higher activity and selectivity than the homogeneous catalyst. The immobilized catalyst could be readily recovered from the reaction mixture by using a simple magnet, and  reused up to five times without any loss of activity

Concentration dependent tautomerism in green [Cu(HL1)(L2)] and brown [Cu(L1)(HL2)] with H2L1 = (E)-N’-(2-hydroxy-3-methoxybenzylidene)- benzoylhydrazone and HL2 = pyridine-4-carboxylic (isonicotinic) acid

The in situ formed hydrazone Schiff base ligand (E)-N’-(2-hydroxy-3-methoxybenzylidene)-benzoylhydrazone (H2L1) reacts with copper(II) acetate in ethanol in the presence of pyridine-4-carboxylic acid (isonicotinic acid, HL2) to green-[Cu(HL1)(L2)]・H2O・C2H5OH (1) and brown-[Cu(L1)(HL2)] (2) complexes which crystallize as concomitant tautomers where either the mono-anion (HL1)- or di-anion (L1)2- of the Schiff base and simultaneously the pyridine-carboxylate (L2)- or the acid (HL2) (both through the pyridine nitrogen atom) function as ligands. The square-planar molecular copper(II) complexes differ in only a localized proton position either on the amide nitrogen of the hydrazone Schiff base in 1 or on the carboxyl group of the isonicotin ligand in 2. The proportion of the tautomeric forms in the crystalline solid-state can be controlled over a wide range from 1:2 = 95 : 5 to ~2 : 98 by increasing the solution concentration. UV/Vis spectral studies show both tautomers to be kinetically stable (inert), that is, with no apparent tautomerization, in acetonitrile solution. The UB3LYP/6-31+G* level optimized structures of the two complexes are in close agreement with experimental findings. The solid-state structures feature 1D hydrogen-bonded chain from charge-assisted O(-) … H–N and O–H … (-)N hydrogen bonding in 1 and 2, respectively. In 1 pyridine-4-carboxylate also assumes a metal-bridging action by coordinating a weakly bound carboxylate group as a fifth ligand to a Cu axial site. Neighboring chains in 1 and 2 are connected by strong π-stacking interactions involving also the five- and six-membered, presumably metalloaromatic Cu-chelate rings

N′-[(E)-2-Hydroxy-5-iodobenzylidene]-4-methylbenzenesulfonohydrazide

In the title molecule, C14H13IN2O3S, the dihedral angle between the planes of the benzene and toluene rings is 84.3 (3)°. The molecule displays a trans conformation with respect to the C=N bond. There is an intramolecular O—H...N hydrogen bond with the azomethine N atom as acceptor. In the crystal, N—H...O hydrogen bonds connect the molecules into chains running along the b axis

trans-Diaquabis(l-phenylalaninato-κ2N,O)nickel(II)

In the title compound, [Ni(C9H10NO2)2(H2O)2], the coordination geometry around the NiII ion can be described as distorted octahedral, with two N atoms and two O atoms from phenylalaninate ligands in the basal plane and two aqua O atoms at the axial sites. The crystal packing is stabilized by intermolecular O—H...O and N—H...O hydrogen bonds

Diaquabis( L

L-Phenylalanine reacts with nickel-exchanged zeolite Y to form diaquabis(L-phenylalaninato)nickel(II), which is encapsulated in the pores of the zeolite. In this zeolite-encapsulated form, the nickel derivative functions as an efficient catalyst when cyclohexene, toluene and ethyl benzene are oxidized by hydrogen peroxide in the presence of sodium bicarbonate (as co-catalyst). The catalyst was readily recovered from the reaction mixture, and it could be re-used for other three runs without noticeable loss of activity. The heterogeneous catalyst exhibited significantly higher activity and selectivity compared with diaquabis(L-phenylalaninato)nickel(II) itself

Selective Liquid-Liquid Extraction of Lead Ions Using Newly Synthesized Extractant 2-(Dibutylcarbamoyl)benzoic Acid

A new carboxylic acid extractant, named 2-(dibutylcarbamoyl)benzoic acid, is prepared and its potential for selective solvent extraction and recovery of lead ions from industrial samples was investigated. The slope analysis indicated that the lead ions are extracted by formation of 1:2 metal to ligand complexes. The effect of the parameters influencing the extraction efficiency including kind of the organic diluent, extractant concentration, type of the salt used for ionic strength adjustment, contact time and temperature was evaluated and discussed. Under optimized conditions (aqueous phase: 5 ml, initial lead concentration 1 × 10-4 M, pH 4, sodium chloride 0.1 M; organic phase: 5 ml dichloromethane, ligand concentration 0.05 M), a quantitative (75.2 ± 0.8%) and highly selective extraction of lead ions in the presence of zinc, nickel, cobalt and cadmium ions (each 1 × 10-4 M) was achieved, after 20 min. magnetically stirring of the phases, at      25 °C. The extracted lead ions were stripped from the organic phase by diluted nitric acid (0.1 M) solution. The proposed method was successfully applied for separation of lead from industrial samples. The study of the effect of temperature allowed evaluating the thermodynamic parameters of the extraction process of lead ions by the studied extractant into dichloromethane

Manganese(II) complexes of hydrazone based NNO-donor ligands and their catalytic activity in the oxidation of olefins

The reaction between tridentate NNO donor hydrazone ligands, (E)-2-cyano-N-(phenyl(pyridin-2-yl)methylene)acetohydrazide (HL1) and (E)-2-cyano-N-(1-(pyridin-2-yl)ethylidene)acetohydrazide (HL2), with MnCl(2)4H(2)O in methanol resulted in [Mn(HL1)Cl-2(CH3OH)] (1) and [Mn(HL2)Cl-2(CH3OH)] (2). Molecular structures of the complexes were determined by single-crystal X-ray diffraction. All of the investigated compounds were further characterized by elemental analysis, FT-IR, TGA, and UV-Vis spectroscopy. These complexes were used as catalysts for olefin oxidation in the presence of tert-butylhydroperoxide (TBHP) as an oxidant. Under similar experimental conditions with equal manganese loading, the presence of [Mn(HL2)Cl-2(CH3OH)] (2) resulted in higher conversion than [Mn(HL1)Cl-2(CH3OH)] (1). [GRAPHICS

Selective oxidation of sulfides and hydrocarbons with H2O2 over manganese catalyst supported on nanoparticles

University of ZanjanA new magnetically separable catalyst consisting of binuclear Mn(II) complex [Mn-2 (HL)(2) (H2O)(4)], HL = 2-[(2-hydroxy-benzylidene)-amino]-3-(4-hydroxyphenyl)-propionic acid, supported on (3-chloropropyl)-trimethoxysilane (CPTMS) functionalized silica-coated magnetic nanoparticles (MNPs) was prepared. The synthesized catalyst was characterized by several physico-chemical and spectroscopic methods. This immobilized complex was found to be an efficient heterogeneous catalyst for the oxidation of different sulfides and hydrocarbons using hydrogen peroxide (H2O2) as an oxidant. The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no considerable loss of catalytic activity

Azobenzene based 2D-MOF for high selective quinone fluorescence sensing performance

The present work describes development of a simple and cost-effective fluorescence sensor for determination of quinone specially 1,8-dihydroxyanthraquinone (danthron). A 2D-metal-organic framework (TMU-54) containing the azobenzene group has been synthesized and applied as an efficient fluorescent sensor for danthron detection. The key feature that has a great impact on the properties of the material is the presence and distribution of functional groups within the structure. We discuss the relationship between the nature and structure of the specifically designed organic linker as well as the properties of this framework in fluorescence recognition of quinones. TMU-54 ([Cd3(adc)6(DMF)2]) is capable of distinguishing complementary and mismatched target sequences with high sensitivity and a significant Ksv (1049) value