Synthesis, characterization and thermal analysis of 1:1 and 2:3 lanthanide(III) citrates |
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Authors: | M F P da Silva J R Matos P C Isolani |
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Institution: | 1. Instituto de Química, Universidade de S?o Paulo, CP 26077, S?o Paulo, SP, 05513-970, Brazil
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Abstract: | The synthesis and characterization of lanthanide(III) citrates with stoichiometries 1:1 and 2:3; LnL·xH2O] and Ln2(LH)3·2H2O], Ln=La, Ce, Pr, Nd, Sm and Eu are reported. L stands for (C6O7H5)3? and LH for (C6O7H6)2?. Infrared absorption spectra of both series evidence coordination of carboxylate groups through symmetric bridges or chelation. X-ray powder patterns show the amorphous character of LnL·xH2O]. The compounds Ln2LH3·2H2O] are crystalline and isomorphous. Emission spectra of Eu compounds suggest C 2v symmetry for the coordination polyhedron of LnL·xH2O] and C 4v for Ln2(LH)3·2H2O]. Thermal analyses (TG-DTG-DTA) were carried out for both series. The thermal analysis patterns of the two series are quite different and both fit in a 4-step model of thermal decomposition, with lanthanide oxides as final products. |
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