Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) transition metals isonicotinate complexes: Thermal behavior in N-2 and air atmospheres and spectroscopic characterization

Autor(es)

Goncalves Nunes, Wilhan Donizete ^[1] ; Teixeira, Jose Augusto ^[1] ; Ekawa, Bruno ^[1] ; Carneiro Soares do Nascimento, Andre Luiz ^[1] ; Ionashiro, Massao ^[1] ; Caires, Flavio Junior ^{[1, 2]}

Afiliação do(s) autor(es)

^[1] Univ Estadual Paulista UNESP, Inst Quim, Araraquara, SP - Brazil

^[2] Univ Estadual Paulista Unesp, Fac Ciencias, Bauru, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Thermochimica Acta; v. 666, p. 156-165, AUG 10 2018.
• Citações Web of Science: 3

Resumo

Solid-state M(IN)(2)center dot nH(2)O complexes, where M stands for bivalent transition metals (Mn, Fe, Co, Ni, Cu and Zn), IN is isonicotinate and n = 0.5 to 4.0 H2O, were synthesized. Characterization and thermal behavior of the compounds were performed employing elemental analysis (EA), complexometric titration with EDTA, powder X-ray diffraction (PXRD), infrared spectroscopy (FTIR), simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC) in dynamic dry air and nitrogen atmospheres, differential scanning calorimetry (DSC) and TG DSC coupled to FT1R. The thermal behavior of isonicotinic acid and its sodium salt was also investigated in both atmospheres. The dehydration of these compounds occurs in a single step in both atmospheres. In air atmosphere, the thermal decomposition of the anhydrous compounds also occurs in a single step, except for the copper compound where two steps are observed. In N, the thermal decomposition of the anhydrous compounds occurs in two consecutive steps, except for iron compound, where three steps are observed. The main gaseous products of thermal decomposition/pyrolysis of the compounds were identified as CO, CO2 and Pyridine. Mn, Co, Cu and Zn compounds show a physical transformation process in DSC curves. The ligand coordinates through the pyridine nitrogen atom to the metal and for the Zn compound, the carboxylate group also participates in the coordination. The IR absorption profile of hydrated and dehydrated compounds suggest that there is a probable change in the coordination mode of the ligand upon dehydration. This change needs to be further investigated, once it is not possible to ensure only with infrared spectroscopy data. (AU)

• Processo FAPESP: 17/14936-9 - Preparação, caracterização e estudos termoanalíticos de catalisadores heterogêneos de selenatos duplos de Mg/Co e Mg/Cu na produção de biodiesel a partir de diferentes óleos
• Beneficiário: Massao Ionashiro
• Modalidade de apoio: Auxílio à Pesquisa - Regular