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Summary
The new mixed-ligand complexes of d-electron metals (M(II)=Mn, Ni, Cu) with 2,2'-bipyridine (2-bpy) and mono- or dichloroacetates were prepared as crystalline solids. The general formulae of the synthetized complexes are: Cu(2-bpy)2(CClH2COO)22H2O, Mn(2-bpy)2(CCl2HCOO)2, M(2-bpy)2(CCl2HCOO)22H2O (M(II)=Ni, Cu). The compounds were characterized by chemical analysis, IR and VIS spectroscopy. Their magnetic, molar conductivity and thermal properties also were studied. During heating in air complexes decompose via different intermediate products to metal oxides. A coupled TG-MS system was used to analyse the principal volatile thermal decomposition (or fragmentation) products of 2,2'-bipyridine-chloroacetato complexes.
Abstract
Melting enthalpy and mixing enthalpy of binary system 2,4-dinitrotoluene and nitrocellulose were determined by DSC method. The maximum value of mixing enthalpy was H max M=1.38 kJ mol−1 for molar fraction x w24DNT = 0.501. The Flory-Huggins parameter (c) was estimated. The solubility curves and glass transition temperatures were predicted and compared with the experimental results. The measurements were performed for the samples with different times of storage at room temperature. The analysis of melting peaks for the mixture leads to the conclusion that for the long periods of storage the melting of 2,4-dinitrotoluene takes place in the confined spaces (pores) and unconfined space (bulk). The crystallization and melting is observed during the short time of storage in mixtures with low nitrocellulose content and in the case of mixtures with a large amount of NC the glass transition is additionally observed.
Abstract
The physico-chemical properties and thermal stability in air of the light lanthanide 2,3- and 3,5-dimethoxybenzoates were studied and compared in order to observe if there is influence of the position of -OCH3 substituents in benzene ring on their properties, mainly on their thermal stability. The complexes of both of two series are crystalline, hydrated or anhydrous salts with colours typical of Ln3+ ions. The carboxylate group shows the different coordination modes. It may coordinate as a bidentate, chelating or tridentate chelating-bridging ligand. The thermal stabilities of 2,3- and 3,5-dimethoxybenzoates of light lanthanides were studied in the temperature range 293-1173 K. The solubilities of 2,3- and 3,5-dimethoxybenzoates of these elements in water at room temperature are in the orders of 10-3-10-2 mol dm-3 and 10-4 mol dm-3, respectively. The various positions of -OCH3 groups in benzene ring influences some physico-chemical properties of these compounds.
A 2-year field study was conducted during the rainy seasons of 1999 and 2000 at Houfa in northern Jordan, to study the performance of two wheat cultivars ACSAD 65 and F8 and their response to hand weeding (practised monthly during the growing seasons) and 2,4-D application at different growth stages. In both growing seasons, no significant differences (P≤0.05) in grain yield were recorded between the cultivars studied. Differences in weed number and fresh weight were significant between the various treatments in both seasons. Hand weeding proved the best method of weed control. In both growing seasons, yield reductions occurred when 2,4-D was applied to wheat, irrespective of the stage of application. Hand weeding treatment was more effective than 2,4-D application in suppressing weed growth.
. [2]. A. Cavazzini F. Gritti K. Kaczmarski N. Marchetti
Research over the last few years has shown that inoculation with nitrogen-fixing bacteria of the genus Azorhizobium presents an alternative for (or supplement to) chemical fertilization, mainly due to the capability of the bacteria to produce plant growth- promoting hormones. The Azorhizobium caulinodans strain ORS 571 in combination with 2,4-D was able to colonize the root interior of an Indian maize cultivar. After transplanting to pots, it was noticed that nodulated and Azorhizobium -treated plants showed higher chlorophyll content in the leaf and enhanced nitrate reductase activity, leading to higher yield as compared to the control plants (non-nodulated). A plant growth-promoting effect was clearly visible in all inoculated plants examined. nodulated plants treated with Azorhizobium had higher physiological activities as compared to plants treated only with Azorhizobium . Azorhizobium therefore creates potentially better symbiosis in the form of para -nodules and promotes a higher level of nitrogen fixation, leading to better growth and plant development, with reduced requirements for chemical fertilizers.
Abstract
The physico-chemical properties and thermal stability in air of light lanthanide 2,3-, 2,4- and 3,4-dimethoxybenzoates were compared and the influence of -OCH3 substituent on their thermal stability was investigated. The complexes of these series are crystalline, hydrated or anhydrous salts with colours typical of Ln3+ ions. The carboxylate group is a bidentate, chelating (2,4- and 3,4-dimethoxybenzoates) or tridentate chelating and bridging ligand (2,3- dimethoxybenzoates). The thermal stability of 2,4- , 3,4- and 2,3- dimethoxybenzoates of light lanthanides was studied in the temperature range 273-1173 K. The positions of methoxy groups in benzene ring influence the thermal properties of the complexes and their decomposition mechanism.
acceptance, and application possibility as powder form. The most commonly used ceramic materials in orthopedics are oxide ceramics (Al 2 O 3 and ZrO 2 ), due to their excellent biocompatibility. However, among the biocompatible materials was Si 3 N 4
Abstract
Four new mixed ligand complexes were prepared by the reaction of title metal dichloroacetates and 2,4'-bipyridine. The general formulae of synthesized compounds are M(2,4'-bpy)2(CCl2HCOO)2 nH2O (where M(II)=Mn, Co, Ni, Cu; 2,4'-bpy=2,4'-bipyridine, n=2 or 4). The complexes have been isolated from aqueous media and characterized by chemical analysis, molar conductance (in MeOH, DMSO and DMF), magnetic, IR and VIS spectral studies. The nature of metal(II)-ligand coordination is discussed. The thermal behaviour of obtained complexes was studied by thermal analysis and TG-MS techniques in air. IR, X-ray powder diffraction and thermoanalytical data were used for the determination of solid intermediate products of the thermal decomposition. The principal volatile products of thermal decomposition of complexes were proved by mass spectroscopy: H2O+, CO+ 2, HCl+ 2, Cl+ 2, NO+ and other.
