Kinetics and thermal decomposition of Fe(III) and UO2(II) complexes with embelin (2,5-dihydroxy-3-undecyl-P-benzoquinone)

Dhar, Manoj K.; Singh, Onkar

doi:10.1007/bf02055928

Cited by 30 publications

(11 citation statements)

References 5 publications

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“…The change in enthalpy (ΔH) for any phase transformation [37] taking place at any peak temperature, Tm, can be given by the following equation: ΔS = ΔH/T m . Based on least square calculations, the Ln ΔT versus 1000 / T plots for all complexes, for each DTA curve, gave straight lines from which the activation energies were calculated according to the reported methods [38].…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of thermally stable aromatic polyamides and poly(1,3,4-oxadiazole-amide)s nanoparticles containing pendant substituted bezamides

Hassan

Elhusseiny

Elkony

et al. 2013

Chemistry Central Journal

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BackgroundThe introduction of pendent bulky groups along the polymer backbone results in a less ordered polymer matrix and increases the solubility characteristics without affecting thermal properties. The inclusion of chromogenic chemical moieties in the chains can give rise to the luminescent converter material which permits the preparation of materials with potential applications. Aromatic polymers containing heterocyclic rings in the main chain are known for their high thermal resistance, good hydrolytic stability, low dielectric and tough mechanical properties. There is currently much research directed towards the discovery of new blue light-emitting polymers, with characteristics of high efficiency and high reliability. Herein, we describe the preparation of aromatic polyamides and poly (1,3,4-oxadiazole-amide)s nanoparticles with pendant structures comprised of m- and p-acetoxybenzamide groups, where the acetoxybenzamide groups act as signaling units due to their fluorescent and chromogenic characteristics.ResultsAromatic polyamides and poly(1,3,4-oxadiazole-amide)s nanoparticles with pendant structures comprised of m- and p-acetoxybenzamide groups were successfully prepared and characterized using different analytical methods. Most polyamides were obtained as well-separated spherical nanoparticles while aramide containing pyridine produced aggregated particles attributed to the molecular self assembly via H-bond directed organization of molecular precursors. The thermal behavior of all polymers exhibited two major thermal decompositions due to the subsequent breakage of the acetoxy group in the lateral chain and cleavage of the main amide bonds. Photoluminescence studies revealed that the blue emissions for the polyamide derived from benzidine were blue-shifted (shifted to a lower wavelength) compared to that of polyamides containing flexible linkages.ConclusionsWe report the synthesis of aromatic polyamides and poly(1,3,4-oxadiazole-amide)s nanoparticles with pendant structures comprised of m- and p-acetoxybenzamide groups. The thermal behavior of all polymers exhibited two major decompositions due to breakage of the acetoxy group in the lateral chain and cleavage of the main amide bonds. Structure- photoluminescence correlation demonstrated an interesting connection between structural modification and optical properties. The blue emissions for the polyamide derived from benzidine, attributed to the highly conjugation system, was blue shifted with the introduction of flexible linkages. The prepared polymers dissolved in warm polar aprotic solvents. Further investigations to obtain films with reasonably good mechanical properties for different applications are in progress.

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Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of thermally stable aromatic polyamides and poly(1,3,4-oxadiazole-amide)s nanoparticles containing pendant substituted bezamides

Hassan

Elhusseiny

Elkony

et al. 2013

Chemistry Central Journal

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“…Based on least squares calculations, the ln(Δt) ν. 1000/T plots for the complex, gave straight lines from which the activation energies were calculated according to the method of Piloyan et al [37]. The slope is of the Arrhenius type and equals -E a θ / R.…”

Section: Infrared Spectroscopymentioning

confidence: 99%

The Ni(II) Complex of 2-Hydroxy-Pyridine-N-Oxide 2-Isothionate: Synthesis, Characterization, Biological Studies, and X-ray Crystal Structures using (1) Cu Kα Data and (2) Synchrotron Data

Makhyoun¹,

Palmer²,

Soayed³

et al. 2014

Journal of Materials Science and Nanotechnology

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C 12 H 20 N 6 NiO 6 S 2 or NiL 2 (SCN) 2 ](NH 4 ) 2 .2H 2 O, where L is 2-hydroxy-pyridine-N-oxide, has been prepared and characterized using elemental analyses, IR, UV and visible spectrometry, magnetic moment measurements, thermal analyses and single crystal X-ray analyis. The results indicate that the complex reacts as a bidentate ligand and is bound to the metal ion via the two oxygen atoms of the ligand (HL). The activation energies, ∆E*, entropies ∆S*, enthalpies ∆H* and order of reactions have been derived from differential thermogravimetric (DTA) curves. Based on inhibition zone diameter measurements, the complex exhibited significant antibacterial activity against both Staphylococcus aureus and Escherichia coli. It also exhibited significant antifungal activity against Candida albicans, but no activity was found against Aspergillus flavus. The crystal structure of the Ni(II) complex [C 12 H 20 N 6 Ni O 6 S 2 ], Mr = 467.17, was determined from Cu Kα X-ray diffraction data, λ = 1.54178 Å, at 100 K using direct methods. The crystals are monoclinic, space group P2 1 /n with Z = 4 and a = 8.9893(2) Å, b = 17.6680(5) Å, c = 12.5665(3) Å, β = 108.609(1)°. In parallel with this study corresponding results were derived for the crystal structure determined independently from synchrotron X-ray diffraction data, λ = 0.61990 Å, at 100 K. The unit cell parameters derived in this experiment are a = 9.000(2) Å, b = 17.700(4) Å, c = 12.590(3) Å, β = 108.61(3)°. Both studies show 4 O and 2 N atoms coordinating Ni in a distorted octahedral arrangement. Each of the Ni 2-hydroxy-pyridinium-N-oxide moieties is highly planar and the S=C=N-Ni ligands are approximately linear. The crystal structure is characterised by a number of strong hydrogen bonds.

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“…The values of collision factor, Z, can be obtained in case of Horowitz Metzger by making the use of the relation [24]: Table 1 Analytical data for the complexes of 5-(phenylazo)-6-aminouracil (H 2 L 1 ), 5-( p-anisylazo)-6-aminouracil (H 2 L 2 ) and 5-( p-tolylazo)-6-aminouracil (H 2 L 3 ) where DS # is the entropy of activation, R the molar gas constant, f the rate of heating (K s À1 ), k the Boltzmann constant and h is the Planck's constant [25]. The change in enthalpy (DH # ) for any phase transformation taking place at any peak temperature, T m , can be given by the following equation: DS # = DH # /T m .…”

Section: Thermal Studiesmentioning

confidence: 99%

Thermal properties of some biologically active 5-(p-substituted phenylazo)-6-aminouracil complexes

Masoud

El-Enein

Ramadan

et al. 2008

Journal of Analytical and Applied Pyrolysis

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Kinetics and thermal decomposition of Fe(III) and UO2(II) complexes with embelin (2,5-dihydroxy-3-undecyl-P-benzoquinone)

Cited by 30 publications

References 5 publications

Synthesis and characterization of thermally stable aromatic polyamides and poly(1,3,4-oxadiazole-amide)s nanoparticles containing pendant substituted bezamides

Synthesis and characterization of thermally stable aromatic polyamides and poly(1,3,4-oxadiazole-amide)s nanoparticles containing pendant substituted bezamides

The Ni(II) Complex of 2-Hydroxy-Pyridine-N-Oxide 2-Isothionate: Synthesis, Characterization, Biological Studies, and X-ray Crystal Structures using (1) Cu Kα Data and (2) Synchrotron Data

Thermal properties of some biologically active 5-(p-substituted phenylazo)-6-aminouracil complexes

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