A convenient and efficient one-step method for the synthesis of dicompartmental ligands with hexa- and tetradentate coordination sites

A convenient and more efficient method for the preparation of 1,6-bis(2-pyridyl)-2,5-bis(2-hydroxy-3-formyl-5-methyl benzyl)-2,5-diazahexane, L1H2 and 1,7-bis(2-pyridyl)-2,6-bis(2-hydroxy-3-formyl-5-methyl benzyl)-2,6-diazaheptane, L2H2 are described. The ligands were prepared by reaction of two moles of 3-(chloromethyl)-2-hydroxy-5-methyl benzaldehyde with a mole of N,N'-bis(2-pyridyl)dopamine in THF at ambient conditions in high yield (75-80%).KEY WORDS: Dicompartmental ligand, Synthesis, Phenol-based ligand, Acyclic ligandBull. Chem. Soc. Ethiop. 2010, 24(1), 151-155

Synthesis and characterization of mono- and bimetallic complexes of Zn(II) and Cu(II); new multifunctional unsymmetrical acyclic and macrocyclic phenol-based ligand

The dicompartmental macrocyclic ligand (L2)2- was prepared by [1:1] cyclic condensation of N,N′-dimethyacetate-N,N′-ethylene-di(5-methyl-3-formyl-2-hydroxybenzylamine with 1,3-diaminopropane. The ligand includes dissimilar N(amine)2O2 and N(imine)2O2 coordination sites sharing two phenolic oxygen atoms and containing two methyl acetate pedant arms on the amine nitrogen donor atoms. A series of mono- and bimetallic complexes were synthesized and characterized on the basis of elemental analysis, molar conductance measurement, IR and UV-Vis spectroscopy techniques. It was found that during the cyclization process the copper (II) displaced from the N(amine)2O2 to the N(imine)2O2 coordination site and one of the methyl acetate pedant arms is dissociated. The heterodinuclear complex of [ZnL2Cu(-OAc)]+ was prepared by a transmetallation reaction on the [ZnL2Zn(-OAc)]+ by Cu(II). The characterization results showed that the two metal ions are bridged by two phenolic oxygen atoms and an acetate group, providing distorted five-coordination geometries for the both metal ions

Synthesis and characterization of cobalt doped zinc oxide nanoparticles by microwave method and its application as catalyst for biodiesel production from soybean oil

Today, biodiesel is being produced and consumed around the world as one of the main sources for replacing fossil fuels. In current research, cobalt doped zinc oxide was used as nanocatalyst to produce biodiesel from soybean oil by transesterification reaction. The nanocatalysts used were first prepared by microwave method and identified by X-ray diffraction (XRD), scanning electron microscopy (SEM) and x-ray energy dispersive spectroscopy (EDS). In the next step, the prepared catalysts were used in the reaction of biodiesel production from soybean oil. The produced biodiesel was characterized using nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectroscopy (GC-MS). Optimal reaction conditions of biodiesel production with cobalt doped zinc oxide nanocatalyst obtained, at 3 h, temperature 60 ˚C, catalyst concentration 3% by weight, and molar ratio of oil to methanol 1 to 41 resulted in 98% efficiency. In another part of this research, microwave radiation with a power of 250 W was used as a source of energy in the biodiesel production reaction which in the presence of 4% by weight of catalyst and molar ratio of oil to methanol 1 to 20 resulted in 91% efficiency in 180 s

Solvatochromism Study on the Copper(II) Complexes Containing 3–Substituted Derivatives of Acetylacetonate Ligands

Meeting minutes from the Faculty Senate of the University of Northern Iowa

Effective Oxidation of Sulfides to Sulfoxides with Hydrogen Peroxide under Transition-Metal-Free Conditions

A “green” highly selective oxidation of organic sulfides to the corresponding sulfoxides was developed using hydrogen peroxide and glacial acetic acid under transition metal-free and mild conditions. The oxidation procedure is very simple and the products are easily isolated in excellent yields (90-99%)

Synthesis and reactivity of heterobimetallic complexes with phenolic oxygens bridged ligands

A new efficient method for the synthesis of dicompartmental ligands enalH 2 8 and of tnalH2, 10 is described. This method is essentially a concise one-step route via the Mannich condensation, from 4-methyl 2-formylphenol and paraformaldehyde with appropriate amines. A series of macrocyclic heterobimetallic complexes of type [Mc(tntnam)M o](PF6)n and [Mc'(tntnim)Ni](PF 6)n where Mc = Co(III) and Zn(II), Mc ' = Co(II), Co(III) and Zn(II) and Mo = Ni(II), Cu(II) and Zn(II) have been synthesized and characterized. The macrocyclic ligands tntnim 12 and tntnam 13 contain two geometrically distinct 6-coordinate (closed-site) and 4-coordinate (open-site) compartments which are bridged by phenolic oxygens. The heterobimetallic complexes with Zn(II) or Ni(II) in the open-site are primarily formed as 5-coordinate with a chloride ion as a fifth ligand; the latter can be removed by Ag+ ion. The 1H NMR and 13C NMR of diamagnetic complexes and [Co(tntnam)ZnCl](PF6)2, 27 and [Co(tntnam)Zn](PF6)3, 28 demonstrate that the expected trans pyridine structures are formed. Solution magnetic moments of heterobimetallic complexes indicate that all Co(III) ions are spin paired, but the Ni(II) ions are spin free. The electronic absorption and emission spectra and redox couples are reported. The crystal structures of [Zn(tntnim)NiCl]PF 6•C2H5OH, 16, [Zn(tntnam)Ni](PF 6)2, 22, [Zn(tntnam)Cu](PF6) 2, 23, and [Co(tnmam)Ni(H2O)](PF6) 3•4H2O, 25 were determined. The crystal structures demonstrate that the expected 'trans' pyridine structures are formed. Photoreactivity of heterobimetallic complexes towards molecular oxygen showed that, in spite of sensitivity of these complexes to molecular oxygens no singlet molecular oxygen, O2 (1[Delta]g ), or peroxide species were generated as a result of irradiation with visible light. A series of acyclic ligands analogous to the dialdehyde ligand enalH 2, but containing different ligating groups instead of the aldehyde moieties were prepared. These include dialcoholic ligands of enolH4 and tnolH4, diimine ligand of enmimH2, and diamine ligand of enmamH2. Exploration of the coordination chemistry of these ligands revealed that the presence of an "en" in the closed-site solely provides a C2 symmetrical isomer among the three possible topological isomers. Monometallic complexes of [Co(enolH2)] +, [Co(tnolH2)]+, [Cr(tnolH2)] +, (Zn(enmim)(H+)2]2+, [Zn(enmam)(H +)2]2+ and [Cr(enmam)(H+) 2]3+ and heterobimetallic complexes [Zn(enmam)Cu] 2+ and [Cr(enmam)Cu]3+ have been prepared and characterized. Syntheses of [Zn(enmam)(H+)2]2+ through two different routes reveals that introduction of a metal into free ligand enmamH2 selectively occupies the closed-site cavity and leaves the open-site cavity intact

Effective Oxidation of Sulfides to Sulfoxides with Hydrogen Peroxide under Transition-Metal-Free Conditions

A “green†highly selective oxidation of organic sulfides to the corresponding sulfoxides was developed using hydrogen peroxide and glacial acetic acid under transition metal-free and mild conditions. The oxidation procedure is very simple and the products are easily isolated in excellent yields (90-99%)

Preparation of heterodinuclear complexes with phenol-based compartmental ligands containing hexa- and tetradentate coordination sites

A series of mono- and heterodinuclear complexes of type MLnH2 and MLnM′ where M = CoIII, CrIII, ZnII and M′ = CuII, ZnII have been synthesized and characterized. The crystal structure of [CrIIIL2H2]ClO4 was determined and discussed

Syntheses, crystal structures and solvatochromic properties of dinuclear oxalato-bridged copper(II) complexes

<p>Three dinuclear copper(II) complexes, [Cu₂(L¹)₂(μ-ox)](ClO₄)₂⋅2(CH₃CN), [Cu₂(L²)₂(μ-ox)](ClO₄)₂⋅H₂O, and [Cu₂(L³)₂(μ-ox)](ClO₄)₂ where ox = oxalato; L = <i>N</i>,<i>N</i>-dimethyl,<i>N</i>′-benzylethane-1,2-diamine, <b>L</b>^<b>1</b>, <i>N</i>,<i>N</i>-diethyl,<i>N</i>′-benzylethane-1,2-diamine, <b>L</b>^<b>2</b>, <i>N</i>,<i>N</i>-diisoprophyl,<i>N</i>′-benzylethane-1,2-diamine, <b>L</b>^<b>3</b>, were prepared and characterized by elemental analyses, spectral (IR, UV–Vis) data and molar conductance measurements. The crystal structures of [Cu₂(L¹)₂(μ-ox)](ClO₄)₂⋅2(CH₃CN) and [Cu₂(L³)₂(μ-ox)](ClO₄)₂ have been determined by single-crystal X-ray analysis. Solvatochromic behaviors were investigated in various solvents, showing positive solvatochromism. The effect of steric hindrance around the copper ion imposed by <i>N</i>-alkyl groups of the diamine chelates on the solvatochromism property of the complexes is discussed. Solvatochromism was also studied with different solvent parameter models using stepwise multiple linear regression method.</p