Synthesis,characterization and thermal behaviour of solid 2-methoxybenzoates of trivalent metals

Solid-state Ln(L)₃ compounds, where Ln stands for trivalent Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y and L is 2-methoxybenzoate have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results provided information on the composition, dehydration, coordination mode, structure, thermal behaviour and thermal decomposition.     

Synthesis,characterization and thermal behaviour of solid-state compounds of europium(III) and gadolinium(III) 3-methoxybenzoate

Solid-state Ln–C₈H₇O₃ compounds, where Ln stands for Eu(III) and Gd(III) and C₈H₇O₃ is 3-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration, thermal stability and decomposition of the isolated compounds.     

Solid-state 2-methoxybenzoates of light trivalent lanthanides

Solid-state LnL₃ compounds, where L is 2-methoxybenzoate and Ln is light trivalent lanthanides, have been synthesized. Thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy and elementary analysis were used to characterize and to study the thermal behaviour of these compounds. The results led to information on the composition, dehydration, thermal stability and thermal decomposition of the isolated compounds. On heating these complexes decompose in three (Ce, Pr) or five (La, Nd, Sm) steps with the formation of the respective oxide: CeO₂, Pr₆O₁₁ and Ln₂O₃ (Ln=La, Nd, Sm) as final residues. The theoretical and experimental spectroscopic study suggests predominantly the ionic bond between the ligand and metallic center.     

Thermal and spectroscopic data to investigate the oxamic acid,sodium oxamate and its compounds with some bivalent transition metal ions

Synthesis, characterization, and thermal behavior of transition metal oxamates, M(NH₂C₂O₃)₂·nH₂O (M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II)), as well as the thermal behavior of oxamic acid and its sodium salt (NaNH₂C₂O₃) were investigated employing simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), experimental and theoretical infrared spectroscopy, TG-DSC coupled to FTIR, elemental analysis and complexometry. The results led to information about the composition, dehydration, thermal stability, thermal decomposition, as well as of the gaseous products evolved during the thermal decomposition of these compounds in dynamic air and N₂ atmospheres.     

Solid-state compounds of 2-methoxybenzylidenepyruvate and 2-methoxycinnamyllidenepyruvate with thorium (IV)

Solid-state compounds of general formula ThL₄·nH₂O, where L represents 2-methoxybenzylidenepyruvate and 2-methoxycynamylidenepyruvate, were synthesized. Complexometric titrations with EDTA, thermogravimetry (TG), differential thermal analysis (DTA), X-ray powder diffractometry, elemental analysis (EA), and infrared spectroscopy have been employed to characterize and to study the thermal behavior of these compounds in dynamic air atmosphere. The results led to informations about the composition, dehydration, crystallinity, and thermal decomposition of the isolated compounds. The performed molecular calculations in this study were done using the Gaussian 03 routine. Theoretical calculations help in interpretations of FT-IR spectra supplying structural and physicochemical parameters.     

Use of thermal analysis techniques for evaluation of the stability and chemical properties of papaya biodiesel (<Emphasis Type="Italic">Carica Papaya</Emphasis> L.) at low temperatures

Solid state Ln₂–L₃ compounds, where Ln stands for light trivalent lanthanides (lanthanum to gadolinium), except promethium, and L is folate (C₁₉H₁₇N₇O₆), have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy (FTIR), TG coupled to FTIR, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results provided information concerning the stoichiometry, crystallinity, ligand’s denticity, thermal stability, thermal behaviour and identification of the gaseous products evolved during the thermal decomposition of these compounds.     

Synthesis,characterization and thermal behaviour of solid-state 3-methoxybenzoates of heavy trivalent lanthanides and yttrium(III)

Solid-state Ln(L)₃ compounds, where Ln stands for trivalent Tb, Dy, Ho, Er, Tm, Yb, Lu and Y, and L is 3-methoxybenzoate, have been synthesized. X-ray powder diffractometry, infrared spectroscopy, complexometry and elemental analysis were used to characterize the compounds. In order to study the thermal behaviour of these compounds simultaneous thermogravimetry and differential thermal analysis (TG-DTA) and differential scanning calorimetry (DSC) were used. The results provided information on the composition, dehydration, polymorphic transformation, thermal stability and thermal decomposition of the synthesized compounds.     

Thermoanalytical study of heavier trivalent lanthanides fumarates

Solid-state heavier lanthanides fumarates compounds have been synthesized, and the compounds were characterized by employing simultaneous thermogravimetry and differential thermal analysis (TG–DTA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), TG coupled to FTIR, elemental analysis, and complexometry. On heating, the dehydration occurs in a single and two consecutive steps and the thermal decomposition of the anhydrous compounds occurs in consecutive and/or overlapping steps, with formation of the respective oxides: Tb₄O₇ and Ln₂O₃ (Ln=Dy to Lu). The results also led to information about composition, thermal behavior, and the type of coordination of the isolated compounds.     

Synthesis, characterization and thermal studies on solid compounds of 2-chlorobenzylidenepyruvate of heavier trivalent lanthanides and yttrium(III)

Solid-state compounds of general formula LnL_3⋅nH₂O, where Ln represents heavier lanthanides and yttrium and L is 2-chlorobenzylidenepyruvate, have been synthesized. Chemical analysis, simultaneous thermogravimetry-differential analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and infrared spectroscopy have been employed to characterize and to study the thermal behaviour of these compounds in dynamic air atmosphere. On heating these compounds decompose in four (Gd, Tb, Ho to Lu, Y) or five (Eu, Dy) steps. They lose the hydration water in the first step and the thermal decomposition of the anhydrous compounds up to 1200°C occurs with the formation of the respective oxide, Tb₄O₇ and Ln₂O₃ (Ln=Eu, Gd, Dy to Lu and Y) as final residue. The dehydration enthalpies found for these compounds (Eu, to Lu and Y) were: 65.77, 55.63, 86.89, 121.65, 99.80, 109.59, 131.02, 119.78, 205.46 and 83.11 kJ mol^-1, respectively.     

Thermal behaviour of ZINC(II) carboxylate complexes with methyl-3-pyridyl carbamate

Four new complex compounds were prepared by reaction of zinc carboxylate and methyl-3-pyridyl carbamate. The synthesized complex compounds of the general formula (RCOO)₂ZnL₂ (RCOO^-= HCOO^- (form), CH₃COO^- (ac), CH₃CH₂CH₂COO^- (but), (CH₃)₂CHCOO^- (isobut), L= methyl-3-pyridyl carbamate (mpc)) were characterized by chemical analysis, IR spectroscopy and studied by methods of thermal analysis (TG/DTG, DTA). CH₂O, CO₂, (CH₃)₂CO, (C₃H₇)₂CO were found as volatile products of thermal decomposition. ZnO was found as final product of thermal decomposition of the prepared complexes heated up to 700°C. Mass spectroscopy, X-ray powder diffraction method, IR spectra and chemical analysis were used for the determination of the thermal decomposition products. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermoanalytical investigations of niobium(V) complexes of 4-isopropylphenol

Thermal behaviour of newly synthesized niobium(V) aryloxides of composition [NbCl_5−n (OC₆H₄CH(CH₃)₂-4) _n ] (where n = 1 → 5) synthesized by the reactions of niobium pentachloride with 4-isopropylphenol in predetermined molar ratios in carbon tetrachloride has been studied by thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The results showed that thermal decomposition of complex of composition [NbCl₄(OC₆H₄CH(CH₃)₂-4)] resulted in the formation of NbOCl₃ as the ultimate decompositional product while all other complexes yielded Nb₂O₅ as the final product of thermal decomposition. From the mathematical analysis of TG data, the kinetic and thermodynamic parameters viz. energy of activation, frequency factor, entropy of activation, etc. have been evaluated using Coats–Redfern equation.     

The One‐dimensional Polyselenide Compound CsGaSe3

A new one‐dimensional phase, CsGaSe₃ has been synthesized and characterized by single crystal X‐ray diffraction, differential thermal analysis, and single crystal UV/Vis spectroscopy. The structure contains infinite chain anions, [GaSe(Se₂)]^— separated by Cs cations. The Ga³⁺ cation is in a distorted tetrahedral environment coordinated by each two Se^2— and Se₂^2— ions. The red crystals of CsGaSe₃ absorb visible light at energies above 2.25 eV. Differential thermal analysis revealed that the compound does not melt below 1000 °C. Crystal data: CsGaSe₃, monoclinic, space group P2₁/c (No 14), a=7.727(1), b=13.014(3), c=6.705(1), β=106.39(3)°, Z=4, R1=0.0469.     

2-Methoxybenzylidenepyruvatewith heavier trivalent lanthanides and yttrium(III)

Solid-state Ln(2-MeO-BP) compounds, where Ln stands for trivalent Eu to Lu and Y(III) and 2-MeO-BP (which is 2-methoxybenzylidenepyruvate) have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffraction, infrared spectroscopy and other methods of analysis were used to characterize and to study these compounds. On the base of the obtained results an Ln(2MeO-BP)₃·nH₂O general formula can be established.     

Thermal analysis of doped Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>

New environmentally inorganic pigments based on Bi₂O₃ doped by metal ions, such as Zr⁴⁺ and Dy³⁺ have been developed and characterized using the methods thermal analysis, X-ray powder diffraction, and spectral reflectance data. The compounds having formula Bi_2−x Dy _x/2Zr_3x/8O₃ (x = 0.2, 0.6, 1.0, and 1.2) were prepared by the solid state reaction. Methods of thermal analysis were used for determination of the temperature region of the pigment formation and thermal stability of compounds. The incorporation of doped ions in Bi₂O₃ changes the color from yellow to orange and also contributes to a growth of their thermal stability. This property gives a direction for coloring ceramic glazes.     

Synthesis, characterization and thermal behaviour of solid-state tartrates of heavy trivalent lanthanides and yttrium(III)

Solid state Ln₂-L₃ compounds, where Ln stands for heavy trivalent lanthanides (terbium to lutetium) and yttrium, and L is tartrate [(C₄H₄O₆)^?2] have been synthesized. Simultaneous thermogravimetry and differential thermal analysis, differential scanning calorimetry, X-ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results provided information concerning the stoichiometry, crystallinity, ligand??s denticity, thermal stability and thermal behaviour of these compounds.     

Synthesis,spectroscopic and thermal studies of 2,3-naphthalenedicarboxylates of rare earth elements

The complexes of rare earth elements with 2,3-naphthalenedicarboxylic acid of the formula: Ln₂(C₁₂H₆O₄)₃·nH₂O, where Ln = La(III)-Lu(III) and Y(III); n = 3 for La(III), Ce(III); n = 6 for Pr(III)-Yb(III) and Y(III) and n = 5 for Lu(III) have been synthesized and characterized by elemental analysis, IR spectroscopy, thermal analysis (TG, DTG, DTA and TG-FTIR) and X-ray analysis. They are sparingly soluble in water and stable at room temperature. During heating in air atmosphere, they lose all water molecules in several steps, generally in two or three steps, except for the La(III) and Ce(III) complexes which lose all water molecules in one step. The anhydrous compounds are stable up to about 773 K and then decompose to corresponding oxides. The thermal decomposition is connected with the release of water molecules (443 K), carbon dioxide (713 K) and hydrocarbons.     

Et3N‐Prompted Efficient Synthesis of Anthracenyl Pyrazolines and Their Cytotoxicity Evaluation against Cancer Cell Lines

A series of anthracenyl pyrazoline derivatives ( 3a – o ) were synthesized with an aim to evaluate their in vitro anticancer activities. Anthracenyl pyrazoline compounds were prepared by the reaction between various anthracenyl chalcones ( 1a – o ) and hydrazine hydrate ( 2 ). The reactions were carried out under reflux in the presence of triethylamine and ethanol for 24 h, and the obtained yields were from good to excellent (90–97%). The structure of each compound is well characterized by IR, ¹H‐NMR, ¹³C‐NMR, elemental analyses, and mass spectroscopic technics, and the molecular structures of compounds 3d and 3e were solved by single‐crystal X‐ray crystallographic methods. The newly synthesized compounds ( 3a – o ) were evaluated for their in vitro cytotoxic studies against four human cancer cell lines MCF‐7 (breast cancer cell lines), SK‐N‐SH (neuroblastoma cancer cell lines), HeLa (cervical cancer cell lines), and HepG2 (liver cancer cell lines), and the screening results show strong cytotoxic effects for most of the synthesized compounds against the three cell lines except SK‐N‐SH cells. Notably, compounds 3a , 3j , 3l , 3m , 3n , and 3o showed a highly potential activity against HeLa cells (IC₅₀: 0.22, 0.3, 0.3, 0.10, 0.25, and 0.25 μM), while compounds 3i , 3k , 3l , and 3m showed a significant cytotoxic activity in HepG2 cells (IC₅₀: 0.22, 0.44, 0.40, and 0.22 μM), whereas compounds 3a , 3b , 3d , and 3e exhibit a promising cytotoxicity against MCF‐7 cells (IC₅₀: 0.73, 0.495, 0.493, and 0.66 μM).     

Hydrothermal syntheses, structures, and magnetic properties of (NH4)2NaVF6 and Na3VF6

The single crystals of perovskite fluorides (NH₄)₂NaVF₆ and Na₃VF₆ were synthesized under mild hydrothermal conditions. The structures of the compounds were determined by means of single-crystal and powder X-ray diffraction analyses, respectively. (NH₄)₂NaVF₆ has a cubic elpasolite-type structure and crystallizes in the space group with lattice constant a=8.495(0) Å. Rietveld refinement indicates that Na₃VF₆ has a monoclinic structure and is in space group P2₁/n. The compounds were characterized by scanning electron microscopy, thermogravimetric and differential thermal analysis, and variable temperature magnetic susceptibility. With the temperature decreasing, the magnetic studies of the compounds showed the magnetic ordering was related to the crystallographic features and isolated magnetic units.     

Thermal behaviour and spectroscopic studies of complexes of some divalent transitional metals with 2-benzoil-pyridil-izonicotinoylhydrazone

New complexes of 2-benzoyl-pyridil-isonicotinoylhydrazone (L) with Cu(II), Co(II), Ni(II) and Mn(II), having formula of type [ML₂] SO₄·xH₂O (M = Cu²⁺, Co²⁺, Ni²⁺, x = 2 and M = Mn²⁺, x = 3), have been synthesised and characterised. All complexes were characterised on the basis of elemental analyses, IR spectroscopy, UV–VIS–NIR, EPR, as well as thermal analysis and determination of molar conductivity and magnetic moments. The thermal behaviour of complexes was studied using thermogravimetry (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The structure of L hydrazone was established by X-ray study on single crystal. The ligand works as tridentate NNO, being coordinated through the azomethine nitrogen, the pyridine nitrogen and carbonylic oxygen. Heats of decomposition, ΔH, associated with the exothermal effects were also determined.     

Bio-based benzoxazine from renewable L-tyrosine: Synthesis,polymerization, and properties

Developing thermosets derived from renewable sources is of great importance. In this work, a fully bio-based benzoxazine monomer, 3,6-bis((3-(furan-2-ylmethyl)-3,4-dihydro-2H-benzo[e][1,3]oxazin-6-yl)methyl)piperazine-2,5-dione (TCDPF), is conveniently synthesized from L-tyrosine cyclic dipeptide (TCDP), furfurylamine and paraformaldehyde. The chemical structure of TCDPF is confirmed by nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy (FT-IR) techniques. The curing behavior of TCDPF is investigated by differential scanning calorimetry and in situ FT-IR techniques. After temperature-programmed curing, the thermomechanical property and thermal stability of the resulting TCDPF polymer (PTCDPF) are evaluated by dynamic mechanical analysis and thermogravimetric analysis techniques, respectively. It is found that PTCDPF have excellent comprehensive performance such as high glass transition temperature (T_g = 322 °C), high thermal degradation temperature (T_5% = 342 °C, T_10% = 395 °C in N₂ atmosphere), and high char yield (CY = 51.3% at 800 °C in N₂ atmosphere). The results demonstrate that L-tyrosine is a promising bio-based raw material for preparing high performance polybenzoxazines.