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Abstract

A new supramolecular compound [Ni3(Hdatrz)6(sca)2(H2O)4]sca·11H2O (Hdatrz = 3,5-diamino-1,2,4-triazole, H2sca = succinic acid) was synthesized and characterized by elemental analysis, single crystal X-ray diffraction and thermogravimetric analysis. X-ray structural analysis reveals that the crystal is triclinic, space group P − 1 with lattice parameters a = 10.192(2) Å, b = 11.671(2) Å, c = 13.600(3) Å, β = 68.086(3)°, Z = 1, D c = 1.689 g/cm−3, F(000) = 728. The enthalpy change of the reaction of formation in water was determined by an RD496–CK2000 microcalorimeter at 25 °C with the value of −23.71 ± 0.023 kJ mol−1. In addition, the thermodynamics of the reaction of formation in water for the compound was investigated by changing the temperature of the reaction and the fundamental parameters k, E, n, , and were obtained.

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Abstract  

Sensitive and selective nuclear reaction methods have been sought for the nuclear microprobe measurement of the spatial distributions of13C and13C/12C ratios. The13C(α, n)16O reaction, with neutron detection, is the most selective for13C, and has a sensitivity of ca. 100 ppm. The reactions13C(d, p)14C and12C(d, p)13C, with proton detection, are the most sensitive for the simultaneous measurement of13C and12C, with detection limits of 30 and 2 ppm respectively. Less sensitive alternative reaction pairs are;13C(3He, p)15N and12C(3He, p)14N;13C(d, nγ)14N and12C(d, pγ)13C;13C(3He, pγ)15N and12C(3He, pγ)14N. The conditions governing their use, particularly light element interferences, are detailed.

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Abstract  

The physicochemical characterization of the solid-state enantiomers and racemate of efaroxan hydrochloride (C13H17N2O+Cl-, M=252.5 g mol-1) was performed by thermoanalytical methods (differential scanning calorimetry, thermogravimetry and thermomicroscopy) and spectral methods (infrared spectrometry and X-ray diffractometry). The efaroxan enantiomers and racemate were shown to be unstable near the melting point. At the beginning of the decomposition, a loss of hydrogen chloride was observed. However when sealed pans were used, the compounds decomposed at higher temperature, allowing a precise evaluation of the melting enthalpies by means of differential scanning calorimetry. The nature of the racemate and its thermal stability were assessed by evaluating its free formation enthalpy. An enantiotropic solid-solid transformation (II→I) was noted for the racemate; the reverse process (I→II) follows zero-order kinetics.

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Abstract  

C60 fullerene was radiolyzed in toluene solution both in presence of air and in vacuum at four different radiation doses 12, 24, 36, 48 and 96 kGy. Clear evidences of the addition of benzyl radicals to the fullerene cage derive from FT-IR and C13-NMR spectra of the reaction product. In presence of air the interference of oxygen is evident in the FT-IR spectra and from the elemental analysis. A detailed analysis of the kinetics of the multiple addition of benzyl radicals to the fullerene cage was made spectrophotometrically with the determination of the addition rate constants at the each addition step and the average number of benzyl groups added to the fullerene cage as function of the radiation dose.

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Abstract  

Four sulphato and nitrato complexes of cerium(IV),viz. (NH4)4Ce(SO4)4·2H2O (1), (NH4)2Ce(SO4)3 (2), (NH4)2Ce(NO3)6 (3) and Cs2Ce(NO3)6 (4) were studied by simultaneous TG/DTA under various experimental conditions in order to establish their decomposition mechanism and to compare the results with the literature data which have been reviewed. In the case of the ammonium compounds (1, 2 and3) the decompositions are accompanied by changes in the oxidation state of cerium; the presence of Ce(III) and Ce(IV) were studied byex situ magnetic susceptibility and XPS measurements. The crystal structure of (1) was determined as well. It forms monoclinic crystals with space groupP21/c; the parameters of the unit cell are:a=12.638(18) Å,b=11.362(10) Å,c=13.607(11) Å, β=110.17(9)°,V=1834.05 Å3.

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This study was conducted to develop a low cost method to preserve papaya (Carica papaya L.) pulp at ambient temperature with a combination of treatments including acid, heat, and cinnamon oil. Papaya pulp processed without and with 200 ppm cinnamon essential oil at pH 5.1, 81 °C, 7 min (ST2 and ST3); pH 3.9, 69 °C, 13 min (ST4 and ST5); and pH 4.5, 75 °C, 15 min (ST6 and ST7) was stored for 8 weeks at ambient temperature (28±2 °C). The cinnamaldehyde content of the papaya pulp treated with cinnamon oil decreased significantly during storage. ST5 and ST7 retained significantly higher β-carotene contents and lightness values compared to ST4 and ST6 during storage. The results indicated that acidification of papaya pulp to pH 4.5 and pasteurization at 75 °C for 15 min with 200 ppm cinnamon oil can be applied to obtain safe and high quality product, which is stable for 8 weeks at ambient temperature.

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Recently, super rice has gained much importance due to its high yield potential while exogenous application of plant growth regulators (PGRs) is an important aspect in plant development and defense responses under stress conditions. In this study we conducted two pot experiments. Firstly, four super rice cultivars, viz. Peizataifeng, Huayou 213, Yuxiangyouzhan and Huahang 31 were subjected to a series of five chilling temperatures, i.e. 11 °C, 12 °C, 13 °C, 14 °C and 15 °C (day/night) for about 25–27 days. Secondly, seeds of Peizataifeng (super rice) and Yuejingsimiao 2 (non-super rice) were then treated with different combinations of salicylic acid (SA), brassinolide (BR), calcium chloride (CaCl2) and fulvic acid (FA) and then exposed to chilling stress at 13 °C for four days. Resultantly, Peizataifen (super rice) was found with the lowest seedling survival rate at all chilling temperatures among all four super rice cultivars, however, it was still found more resistant when compared with Yuejingsimiao 2 (non-super rice) in the second experiment. Furthermore synergistic effect of all PGRs alleviated low temperature stress in both rice cultivars by improving seedling survival rates, leaf area, seedling dry weight, seedling height, root morphology and by modulating antioxidant enzymes, improving proline content and lowering lipid peroxidation.

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Abstract  

A new co-crystal of theophylline and phthalic acid with 1:1 molar ratio has been prepared. It crystallises in the monoclinic crystal system, space group P21/c, a=11.5258(9), b=10.1405(6), c=13.9066(12) Å, β=106.827(4)°. The structure of the co-crystal has been revealed by single crystal X-ray diffraction. An infinite helical polymeric chain is formed by intermolecular hydrogen bonds of the two neutral constituents. The hydroxyl group and carbonyl oxygen atom in one of the carboxyl groups of phthalic acid form hydrogen bonds to O6 and to N(7)H atoms of theophylline, respectively, while the other carboxyl OH group of phthalic acid is in hydrogen bond to N9 atom of theophylline by very strong intermolecular interactions proven by 1883 cm−1 centred peak in FTIR spectrum. Thermal degradation of this new supramolecular compound is a two-step process in air. At first phthalic acid (47.4%) released up to 230°C, meanwhile it loses water and transforms into phthalic anhydride. In EGA-MS spectra, the characteristic fragments of water (m/z=17, 18) appear from about 180°C, while absorption bands of phthalic anhydride are shown in EGA-FTIR spectrum at about 210°C. In the second step theophylline begins to sublime, melts at 276°C, and then evaporates up to 315°C with minute residues.

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Nickel(II) complexes prepared from NNN type ligands and pseudohalogens

Synthesis, structure and thermal decomposition

Journal of Thermal Analysis and Calorimetry
Authors: F. Nazli Dınçer Kaya, Ingrid Svoboda, Orhan Atakol, Ümıt Ergun, Adnan Kenar, Musa Sari and Kaan Emregül

Abstract  

Six nickel(II) complexes, using azide and thiocyanate ions, have been synthesized from bis-2,6(pyrazol-1-yl)pyridine (pp) and some methyl derivatives, 2-(3,5-dimethyl(pyrazol-1-yl)-6-(pyrazol-1-yl)pyridine (app) and bis-2,6(3,5-dimethyl(pyrazol-1-yl) pyridine (dmpp) in non-aqueous media. The complex structures were analyzed using elemental analysis, IR spectroscopy and thermogravimetry. Appropriate crystals of complex, containing azide [Nipp(N3)2]·MeOH (I) and thiocyanate [Nidmpp(SCN)2·MeOH] (VI) were prepared and the molecular structures determined using X-ray diffraction. Complex I was seen to be dinuclear as stated in literature, space group P21/n, monoclinic, a=10.503, b=10.681, c=13.291 Å, β=106.56° and Z=2 whereas complex VI was found to be mononuclear, space group P21/n, monoclinic, a=8.646, b=12.614, c=20.697 Å, β=97.18° and Z=2. The Ni(II) coordination in both complexes were octahedral. Thermogravimetric studies showed azide containing structures to resemble the characteristics of explosive materials. Coordinative MeOH were seen to leave the structure in thiocyanate containing complexes, followed by irregular degradation above 300°C.

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Abstract  

The13C kinetic isotope fractionation in the decarbonylation of lactic acid of natural isotopic composition by sulfuric acid has been studied in the temperature range of 20–80°C. The13C(1) isotope separation in the decarbonylation of lactic acid by concentrated sulfuric acid depends strongly on the temperature above 40°C. Below this temperature the13C isotope effect in the decarbonylation of lactic acid by concentrated sulfuric acid is normal similarly as has been found inthe decarbonylation of lactic [1-14C] acid. The experimental values of k(12C)/k(13C) ratios of isotopic rate constants for12C and13C are close to, but slightly higher than theoretical13C-kinetic isotope effects calculated (neglecting tunneling) under the asumption that the C(1)-OH bond is broken in the rate-controlling step of the dehydration reaction. Dilution of concentrated sulfuric acid with water up to 1.4 molar (H2O)/(H2SO4) ratio caused the increase of the13C isotope fractionation from 1.0273 found in concentrated sulfuric acid at 80.5°C to 1.0536±0.0008 (at 80.6°C). A discussion of the abnormally high temperature dependence of14C and13C isotope fractionation in this reaction and the discussion of the problem of relative14C/13C kinetic isotope effects is given.

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