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Introduction Azomethine metal complexes attract considerable interest and occupy an important role in the development of the chemistry of chelate systems because of the presence of hard nitrogen, oxygen, and soft sulfur donor

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Abstract  

Thermal and thermo-oxidative stability of some poly(siloxane-azomethine)s obtaining starting from bis(formyl-p-phenoxymethyl)tetramethyldisiloxane and different organic diamines have been investigated by TG+DTG+DSC simultaneous analyses performed in argon flow and air static atmosphere, respectively. TG, DTG and DSC curves of each polymer showed three or four successive degradation steps at different temperatures according to the composition of the sample and the gaseous atmosphere in which the thermal analysis was performed. For each process, the following parameters were evaluated: total mass loss, temperature corresponding to the maximum reaction rate, maximum reaction rate, temperature corresponding to certain mass loss. In order to determine the thermal and thermo-oxidative stabilities of investigated polymers, the following values were determined: T x% — temperature corresponding to x% mass loss, and %Δm T — mass loss at a given temperature T. The obtained orders of stability were correlated with the structure of investigated polymers.

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Introduction Azomethines called also imines are quite often investigated as liquid crystalline (LC) compounds [ 1 – 4 ]. Azomethine bond (HC=N) incorporated into the molecular structure cause increase the length and

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Journal of Radioanalytical and Nuclear Chemistry
Authors: E. Havránek, A. Bumbálová, M. Komová, M. Beláková, P. Butvin, and V. Kettmann

Abstract  

A series of bidentate and tetradentate ligands with azomethine and Ar–OH functional groups derived from salicylaldehyde and primary alkyl or aryl monoamines and diamines has been synthesized and labeled with99mTc at various pH's using stannous chloride as reducing agent. The labeling efficiency was monitored by thin layer and paper chromatography.

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Journal of Flow Chemistry
Authors: Patrizio Salice, Emiliano Rossi, Alessandro Pace, Prasenjit Maity, Tommaso Carofiglio, Enzo Menna, and Michele Maggini

The covalent chemistry of carbon nanostructures has put forth a wide variety of interesting derivatives that widen their potential as functional materials. However, the synthetic procedures that have been developed to functionalize the nanostructures may require long reaction times and harsh conditions. In this paper, we study the continuous flow processing of single-wall carbon nanotubes with azomethine ylides and diazonium salts and demonstrate that this approach is effective to reduce reaction times and tune the properties of the functionalized carbon materials.

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New cadmium complexes of the salicylidene-2-amino-thiophenol (I) and 3-methoxysalicylidene-2-amino-thiophenol (II) Schiff bases have been prepared and characterized by elemental analyses, IR, 1H-NMR spectra, conductimetric and thermogravimetric analyses. The results suggested that the Schiff bases are bivalent anions with tridentate ONS donors derived from the phenolic oxygen azomethine nitrogen and thiophenolic sulphur. The formulae are found to be [MLH2O] and [ML2]for the 1:1 and 1:2 non-electrolytic complexes, respectively. The thermal decomposition of the complexes follows first order kinetics and the thermodynamic parameters of the decomposition are reported.

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Abstract  

New complexes of 2-benzoyl-pyridil-isonicotinoylhydrazone (L) with Cu(II), Co(II), Ni(II) and Mn(II), having formula of type [ML2] SO4·xH2O (M = Cu2+, Co2+, Ni2+, x = 2 and M = Mn2+, x = 3), have been synthesised and characterised. All complexes were characterised on the basis of elemental analyses, IR spectroscopy, UV–VIS–NIR, EPR, as well as thermal analysis and determination of molar conductivity and magnetic moments. The thermal behaviour of complexes was studied using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The structure of L hydrazone was established by X-ray study on single crystal. The ligand works as tridentate NNO, being coordinated through the azomethine nitrogen, the pyridine nitrogen and carbonylic oxygen. Heats of decomposition, ΔH, associated with the exothermal effects were also determined.

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Journal of Thermal Analysis and Calorimetry
Authors: H. El-Boraey, F. El-Saied, and S. Aly

Abstract  

UO2(VI), Sn(IV), Th(IV) and Li(I) complexes of 4-azomalononitrile antipyrine (L) have been isolated and characterized based on IR spectra, 1H NMR, elemental analyses, molar conductance and thermal analysis (DTA/TG). The study revealed that the ligand behaves as a neutral bidentate one and coordination takes place via the carbonyl atom of pyrazolone ring >C=O and the azomethine nitrogen >C=N. The thermal stability of the metal complexes were investigated by thermogravimetry (TG), differential thermal analysis (DTA) techniques and infrared spectra, and correlated to their structure. The thermal study revealed that Th(IV) complexes show lower thermal stability than both UO2(VI) and Sn(IV) complexes.

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Abstract  

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method.

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Transition metal(II) ions with dinegative tetradentate schiff base

Synthetic, thermal, spectroscopic and coordination aspects

Journal of Thermal Analysis and Calorimetry
Authors: H. Parekh, P. Panchal, and M. Patel

Abstract  

Some new coordination polymers of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), obtained from the interaction of metal acetate with dipotassium salt of N,N’-di(carboxyethylidene)terephthalaldehydediimine (K2SB) are described. The products, which have been characterized by elemental analyses, magnetic measurements, thermogravimetric analyses, electronic and infrared spectral studies, have composition, [M(SB)(H2O)2]n. These colored coordination polymers are non-hygroscopic and quite stable at room temperature. On the basis of analytical data and IR studies, a 1:1 metal to ligand stoichiometry has been suggested to these coordination polymers. The IR studies have also revealed that ligands are coordinated to metal ion through carboxy oxygen and azomethine nitrogen. All the studies suggested tetradentate nature of the ligand with octahedral symmetry of the coordination polymers. All the coordination polymers are insoluble in acetone, ethanol, chloroform, methanol, benzene, DMF and DMSO. The thermal decomposition of the coordination polymers is studied and indicates that not only the coordinated water is lost but also that the decomposition of the ligand from the coordination polymers is necessary to interpret the successive mass loss.

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