Synthesis and characterization of lanthanide (Ln) coordination compounds with amino and nitro substituents of the benzene dicarboxylic acids (Ln = La, Eu, Gd, Tb)
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Date
2009
Authors
Tham, Weng Thim
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Abstract
In this work, 16 complexes of lanthanide dicarboxylate (where, Ln = La, Eu and Gd) with
aminodicarboxylate and nitrodicarboxylate acids (aia, ata, nia, nta) have been synthesized and
characterized. All complexes were produced with hydrothermal method at 130 oC. The yields of
the products are around 42-52 %. Two single crystals of the complexes, La-nta, La-aia and a
new polymorph of nia ligand were successfully been synthesized and their structure had been
determined by using the single crystal X-ray crystallography at -173 °C. La2(H2O)6(NBDC)3, Lanta
adopted triclinic crystal system with P-1 space group, while La2(C8H5NO4)3.2H2O, La-aia
and nitroterephthalic acid, nia ligand adopted orthorhombic crystal system with Pbcn and Pbca
space group, respectively. Both crystals have a very compact structure and La adopted a nine
coordination environment. Hydrogen bondings can be found in both La-nta and La-aia
complexes. All the crystals of the complexes have a polymeric structure and this has proved the
ability of the carboxylate groups to form polymeric bonding through -(La-O-La)-.
The FTIR characterization shows that all the complexes have their C=O group being
replaced by distinguish symmetrical and asymmetrical vibrations of COO- peaks upon
complexation. The photoluminescence, PL emission spectra reveal that Eu and Tb complexes
have very good PL emission compared to the La and Gd complexes with Tb-aia having the
highest PL emission among all. TGA analysis showed that all the complexes have high thermal
stability compared to its pure acids and started to decompose in the temperature range of 250-
510 °C. Among all the complexes synthesized, Ln-aia which decomposed only at 400-510 °C,
has the highest thermal stability. The nitro and amino groups in the complexes are not involved
in any coordination after complexation, enabling them to be a potential sensor.
Description
Master
Keywords
Biological Science , Lanthanide Carboxylate , Benzene dicarboxylic acids