Thermal behavior in oxidative and pyrolysis conditions and characterization of some metal p-aminobenzoate compounds using TG–DTA, EGA and DSC-photovisual system

Abstract

Synthesis, thermal and spectroscopic study of solid bivalent transition metal compounds of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with p-aminobenzoate as ligand were performed. The thermal study was performed in oxidative and pyrolysis conditions, using the thermoanalytical techniques: Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), DSC-photovisual system and evolved gas analysis (EGA) by TG/DSC-FTIR. Infrared absorption spectroscopy (FTIR) and powder X-ray diffractometry (PXRD) were employing in the spectroscopic study. The general formula M(L) 2. nH 2 O has been established by TG-DTA, elemental analysis and complexometry with EDTA, where M represents Mn, Co, Ni, Cu and Zn, L is paminobenzoate and n = 0 (Mn, Co), 1 (Ni), 1.5 (Zn), 2 (Cu). In oxidative condition (dry air atmosphere), the thermal decomposition occurred in one, two or three steps, with formation of the respective oxides (Mn 3 O 4, CoO, NiO, CuO and ZnO). Under pyrolysis condition (N 2 atmosphere), the thermal decomposition occurred in three or four steps, with mass loss still being observed up to 1000°C. DSC-photovisual system curves provided information about of the dehydration and phase transformation processes, as well as their enthalpies. The EGA data allowed the identification of gaseous products evolved during pyrolysis and oxidative decomposition. The results of the FTIR and PXRD also provided information on the ligand's denticity and crystallinity of the compounds. 2. Experimental 2.1. Synthesis The p-aminobenzoic acid (H-pABA, C7H7NO2) with 99% purity was

Thermal, spectroscopic and antimicrobial activity characterization of some norfloxacin complexes

“…In nitrogen atmosphere, the TG/DTG curves of the anhydrous compound show at least five steps of mass loss, the first three attributed to the thermal decomposition of the compound, associated with small endothermic events in the DTA curve, and the last two, corresponding to a small exothermic event in the DTA curve, attributed to the pyrolysis of the carbonized material. The residue is a mixture of carbon and CoO, as already observed for similar compounds in another study [19].…”

“…As final residues, all compounds presented its respective bivalent oxide in air atmosphere. In nitrogen atmospheres, the final residues were obtained as a mixture of carbonaceous residue and the bivalent metal oxide, a behavior already described for similar compounds under the same conditions of thermal analysis [19].…”

A Family of [Zn6] Complexes from the Carboxylate-Bridge-Supported Assembly of [Zn2] Building Units: Synthetic, Structural, Spectroscopic, and Systematic Biological Studies

“…For all three complexes, the remaining mass indicates the formation of Na 2 O and ZnO as the possible final residues. 44,57 In the literature, analogous thermal properties have been reported showing the removal of coordinated/uncoordinated H 2 O/ MeOH and CO 2 gases exhibiting endothermic reactions from carboxylate-based compounds. 44,57−59 Analysis of Glucose Level from Blood Serum.…”

“…Consequently, the DTA peaks at T max = 287 °C (strongly exothermic), T min = 325 °C (strongly endothermic), 510 °C (weakly endothermic), 703 °C (strongly endothermic), and 835 °C (weakly endothermic), associated with the multistep thermal decomposition processes, are observed. For all three complexes, the remaining mass indicates the formation of Na 2 O and ZnO as the possible final residues. , In the literature, analogous thermal properties have been reported showing the removal of coordinated/uncoordinated H 2 O/MeOH and CO 2 gases exhibiting endothermic reactions from carboxylate-based compounds. ,− …”

Thermal analysis in oxidative and pyrolysis conditions of alkaline earth metals picolinates using the techniques: TG-DSC, DSC, MWTA, HSM and EGA (TG-DSC-FTIR and HSM-MS)

“…The identification of evolved gases (EGA) in dynamic dry nitrogen atmosphere were carried out using a TG-DSC 1 Mettler Toledo coupled to a Nicolet FTIR spectrophotometer with gas cell and DTGS KBr detector using the method described in reference [29]. The furnace and heated gas cell (250 °C) were coupled through a heated (225 °C ) 120 cm stainless steel transfer line with diameter of 3.0 mm, both purged with dry air and nitrogen (50 mL min −1 ).…”