Síntese, caracterização e estudo termoanalítico dos isoftalatos de lantânio (III), cério (III), praseodímio (III), neodímio (III), samário (III), európio (III) e gadolínio (III)
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2015-01-19
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Universidade Federal de Goiás
Resumo
In the last years the interest in the chemistry of coordination compounds of
polycarboxylic acids and lanthanides or transition metals has substantially increased,
due to their interesting characteristics, such as gas storage (Metal-organic
frameworks compounds), luminescence and magnetic properties. A literature survey
reveals few studies investigating the properties of lighter lanthanide coordination
compounds obtained by soft chemistry routes, and mainly the study of their thermal
properties in air atmosphere. In this work the reaction between sodium isophthalate
and lighter lanthanides solutions (La – Gd) except Pm, led to the formation of two
new coordination compounds, and five already reported in the literature, whose
thermal behavior and infrared spectra was investigated. The compounds was
characterized by simultaneous Thermogravimetric and differential scanning
calorimetry analysis (TG-DSC), differential scanning calorimetry (DSC), Fourier
Transform Infrared Spectroscopy (FTIR), thermogravimetric analyses coupled to
Fourier Transform Infrared spectroscopy (TG-FTIR) and EDTA complexometry.
With the TG-DSC and TG-FTIR data was possible to determinate the general
formula of compounds (Ln2(L)3.nH2O, where Ln = La – Gd, except Pm, L =
isophthalate, n varies from 2 to 13,5), thermal stability and molar dehydration
enthalpy per water molecule, as well as the main evolved gases during thermal
decomposition (H2O, CO2 and CO). The FTIR spectra suggest that metal-ligand
coordination occurs in the bridging bidentate mode.
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NUNES, W. D. G. Síntese, caracterização e estudo termoanalítico dos isoftalatos de lantânio (III), cério (III), praseodímio (III), neodímio (III), samário (III), európio (III) e gadolínio (III). 2015. 59 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Goiânia, 2015.