Schiff base‐substituted polyphenol: synthesis, characterisation and non‐isothermal degradation kinetics

Kaya, İsmet; Doğan, Fati̇h; Bi̇li̇ci̇, Ali̇

doi:10.1002/pi.2570

Cited by 24 publications

(11 citation statements)

References 33 publications

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“…At present, there have been no computational investigations on the catalytic mechanism of saccharopine reductase. However, Schiff base formation has been extensively studied both experimentally and computationally due in part to their common occurrence as reaction intermediates in biochemistry and chemistry [ 4 , 7 , 8 , 9 ]. From these studies it has been shown that Schiff base formation depends on several factors including the solvent, pH, and the chemical nature of the reactants [ 7 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

Section: Introductionmentioning

confidence: 99%

A QM/MM–Based Computational Investigation on the Catalytic Mechanism of Saccharopine Reductase

2011

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Saccharopine reductase from Magnaporthe grisea, an NADPH-containing enzyme in the α-aminoadipate pathway, catalyses the formation of saccharopine, a precursor to L-lysine, from the substrates glutamate and α-aminoadipate-δ-semialdehyde. Its catalytic mechanism has been investigated using quantum mechanics/molecular mechanics (QM/MM) ONIOM-based approaches. In particular, the overall catalytic pathway has been elucidated and the effects of electron correlation and the anisotropic polar protein environment have been examined via the use of the ONIOM(HF/6-31G(d):AMBER94) and ONIOM(MP2/6-31G(d)//HF/6-31G(d):AMBER94) methods within the mechanical embedding formulism and ONIOM(MP2/6-31G(d)//HF/6-31G(d):AMBER94) and ONIOM(MP2/6-311G(d,p)//HF/6-31G(d):AMBER94) within the electronic embedding formulism. The results of the present study suggest that saccharopine reductase utilises a substrate-assisted catalytic pathway in which acid/base groups within the cosubstrates themselves facilitate the mechanistically required proton transfers. Thus, the enzyme appears to act most likely by binding the three required reactant molecules glutamate, α-aminoadipate-δ-semialdehyde and NADPH in a manner and polar environment conducive to reaction.

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Section: Introductionmentioning

confidence: 99%

A QM/MM–Based Computational Investigation on the Catalytic Mechanism of Saccharopine Reductase

2011

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“…The integral method proposed by Coats and Redfern was used to calculate the activation energy of thermal decomposition using Eq . :

\ln (\frac{g (α)}{T^{2}}) = \ln (\frac{A R}{E_{normalt} β}) - \frac{E_{normalt}}{R T}

where

α

is the decomposition fraction,

T

is the absolute temperature, A is the frequency factor, R is gas constant,

E_{normalt}

is the activation energy of thermal decomposition,

β

is the heating rate, and the expressions of

g (α)

for the different solid‐state mechanisms are used as the reported articles . From the plots of

\ln [g (α) / T^{2}]

vs. 1000/ T , which are shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Morphology, thermal, and mechanical properties of poly(butylene succinate) reinforced with halloysite nanotube

Cao

Luo

et al. 2013

Polymer Composites

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Poly(butylene succinate) (PBS)/halloysite nanotube (HNT) nanocomposites were fabricated by melt compounding. The morphology of the nanocomposites was studied by scanning electron microscopy and the results showed that the HNT dispersed uniformly in the PBS matrix. The thermogravimetric analysis results showed that the addition of HNT decreased the decomposition temperature and activation energy, and thus accelerated the thermal degradation of PBS. The differential scanning calorimetry analysis indicated that HNT could serve as nucleating agent for the PBS, and thus increased its crystallization temperature and crystallinity. However, it was demonstrated by the X-ray diffractometry spectra that the incorporation of HNT did not affect the crystal form of PBS. Mechanical tests in flexure, tension, and notched Izod impact demonstrated that the strength and modulus of nanocomposites were increased by the addition of HNT without significant loss of ductility. POLYM. COMPOS., 35:847-855,

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“…Several studies have shown that nonisothermal thermogravimetry (TG) is a powerful tool for characterizing the thermal behavior of polymers. 8,9 Dog an et al…”

Section: Introductionmentioning

confidence: 95%

A new Schiff base epoxy oligomer resin: Synthesis, characterization, and thermal decomposition kinetics

Kaya

Doğan

Gül

2011

J of Applied Polymer Sci

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Oligo{2,2 0 -{1,4-phenylenebis[nitrilomethylylidene]}bis(6-methoxyphenol)} (OPNMMP) was synthesized from o-vanillin and p-phenylene diamine by oxidative polycondensation with NaOCl in an aqueous alkaline. Then, a new Schiff Base epoxy oligomer resin, OPNMMP-epichlorohydrine (EPC), was produced with EPC. The structures of the resulting compounds were confirmed by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, 1 H-NMR, and 13 C-NMR. Further characterization processes were preformed by thermogravimetry (TG)-differential thermal analysis, gel permeation chromatography, and solubility testing. Also, the kinetics of the thermal decomposition of OPNMMP-EPC were investigated by thermogravimetric analysis. The TG curves showed that the thermal decomposition of OPNMMP-EPC occurred in one stage. The kinetic parameters related to the decomposition kinetics of OPNMMP-EPC were obtained from TG curves with the following methods: Friedman, Flynn-Wall-Ozawa, Kissinger, invariant kinetic parameter, and Coats-Redfern (CR), under an N 2 dynamic atmosphere and different heating rates (5, 10, 15, and 20 C/min). The mechanism function and pre-exponential factor were also determined by a master plots method. The apparent activation energies of the thermal decomposition were calculated from these methods for OPNMMP-EPC. The analysis of the results obtained by the CR and master plots methods showed that the decomposition mechanism of OPNMMP-EPC in N 2 was a deceleration-type mechanism.

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Schiff base‐substituted polyphenol: synthesis, characterisation and non‐isothermal degradation kinetics

Cited by 24 publications

References 33 publications

A QM/MM–Based Computational Investigation on the Catalytic Mechanism of Saccharopine Reductase

A QM/MM–Based Computational Investigation on the Catalytic Mechanism of Saccharopine Reductase

Morphology, thermal, and mechanical properties of poly(butylene succinate) reinforced with halloysite nanotube

A new Schiff base epoxy oligomer resin: Synthesis, characterization, and thermal decomposition kinetics

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