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Abstract  

The energy of combustion of crystalline 3,4,5-trimethoxybenzoic acid in oxygen at T=298.15 K was determined to be -4795.91.3 kJ mol-1 using combustion calorimetry. The derived standard molar enthalpies of formation of 3,4,5-trimethoxybenzoic acid in crystalline and gaseous states at T=298.15 K, ΔfHm Θ (cr) and ΔfHm Θ (g), were -852.91.9 and -721.72.0 kJ mol-1, respectively. The reliability of the results obtained was commented upon and compared with literature values.

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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.

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Rare earth elements 1,3,5-benzenetricarboxylates were prepared as solids of the general formula Ln(C9H3O6nH2O, where n=6 for La-Dy and n=4 for Ho-Lu,Y. Their solubilities in water at 293 K are of the order 10-4-10-6 mol dm-3. The IR spectra of the complexes indicate that the carboxylate groups are bridging and bidentate chelates. Hydrated 1,3,5-benzenetricarboxylates lose water molecules during heating in one step (La-Tb), two steps (Y, Ho-Tm) or three steps (Dy, Yb, Lu). The anhydrous complexes are stable up to 573-742 K and decompose to oxides (Ce-Lu) at higher temperatures.

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The investigations concerning the thermal behaviour of a series of Ni(II) and Cu(II) complexes of type [MLCln]· mH2O ((1) M:Ni, L:L(1), n=1, m=2; (2) M:Cu, L:L(2), n=1, m=2; (3) M:Ni, L:L(3), n=2, m=0; (4) M:Cu, L:L(3), n=1, m=2) are presented in this paper. The ligands L(1)-L(3) have been synthesised by template condensation of 1,2-diaminoethane with formaldehyde and 2-amino-1,3,4-thiadiazole-5-thiole or 2-acetamino-1,3,4-thiadiazole-5-sulfonamide. The bonding and stereochemistry of the complexes have been characterised by IR, electronic and magnetic studies at room temperature. The thermal behaviour provided confirmation of the complex composition as well as the number and the nature of water molecules and the intervals of thermal stability. The different nature of the ligands and/or the metallic ions generates a different thermal behaviour for complexes. The complexes do not show biological activity against HIV virus.

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The complexes of 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II) have been synthesized as hydrated polycrystalline solids and characterized by elemental analysis, IR, FIR and electronic spectroscopy, magnetic studies and X-ray diffraction measurements. They possess colours typical of the M(II) ions: Cu-blue, Ni-green, Co-pink. The carboxylate groups bind as monodentate or a symmetrical, bidentate chelating or bridging ligands. The thermal stabilities were determined in air. When heated they dehydrate to form anhydrous salts which are decomposed to the oxides of respective metals. The magnetic susceptibilities of the complexes were measured over the range 77-300 K and the magnetic moments were calculated. The results reveal the complexes of Ni(II) and Co(II) to be high-spin complexes and that of Cu(II) to form dimer.

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Resolution and Discovery
Authors: Taťána Fenclová, Zdeněk Jonšta, Miroslav Hnatko, Josef Kraxner, and Pavol Šajgalík

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

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Acta Microbiologica et Immunologica Hungarica
Authors: Renáta Dóró, Szilvia Marton, Anett Horváth Bartókné, György Lengyel, Zsófia Agócs, Ferenc Jakab, and Krisztián Bányai

-P[x]-Ix-Rx-Cx-Mx-Ax-Nx-Tx-Ex-Hx designates the genotypes of the VP7-VP4-VP6-VP1-VP2-VP3-NSP1-NSP2-NSP3-NSP4-NSP5/6 protein-coding genes [3] . Rotavirus strain surveillance is being conducted worldwide to support ongoing vaccination programs by collecting information about changes

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. A Critical Edition of Xiao Dilu and Yelü Xiangwen. Folkestone: Global Oriental . WU Yingzhe 吴英喆 and András RÓNA-TAS 2019 . ‘ Khitan Studies I. The Glyphs of the Khitan Small Script. 3 . The Consonants, 3.1 Labial Stops.’ AOH 72/1 : 47

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properties of the tellurites Yb 2 (TeO 3 ) 3 , Dy 2 (TeO 3 ) 3 and Er 2 (TeO 3 ) 3 . Experimental, results and discussion The tellurites of rare earth elements Yb 2 (TeO 3 ) 3 , Dy 2 (TeO 3 ) 3 and Er 2 (TeO 3 ) 3 , are

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Introduction Over the last several decades, a formula of ABO 3 has attracted broad interest due to their piezoelectricity, ferroelectricity, colossal magnetoresistivity, and photoluminescence [ 1 – 4 ]. Perovskite and ilmenite

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