Eu<sup>3+</sup>- and Tb<sup>3+</sup>-Dipicolinate
Complexes Covalently Grafted into Kaolinite as Luminescence-Functionalized
Clay Hybrid Materials
Denis Talarico de Araujo
Katia J. Ciuffi
Eduardo J. Nassar
Miguel A. Vicente
Raquel Trujillano
Paulo S. Calefi
Vicente Rives
Emerson H. de Faria
10.1021/acs.jpcc.6b12308.s001
https://acs.figshare.com/articles/journal_contribution/Eu_sup_3_sup_-_and_Tb_sup_3_sup_-Dipicolinate_Complexes_Covalently_Grafted_into_Kaolinite_as_Luminescence-Functionalized_Clay_Hybrid_Materials/4702780
The luminescence
properties of Eu<sup>3+</sup>- and Tb<sup>3+</sup>-dipicolinate (pyridine-dicarboxylate)
complexes covalently grafted
into a kaolinite matrix were studied. The stability of the grafted
lanthanide complexes as a function of the thermal treatment was also
investigated. Kaolinite intercalated with dimethyl sulfoxide was heated
in the presence of melted dipicolinic acid to form dipicolinate-intercalated
kaolinite. The luminescent hybrid solids were obtained by complexation
of Eu<sup>3+</sup> or Tb<sup>3+</sup> cations with this intercalated
solid at cation/ligand molar ratios of 1:1, 1:2, or 1:3. The resulting
materials were characterized by thermal analysis, CHN element analysis,
powder X-ray diffraction, infrared absorption spectroscopy, and photoluminescence.
The lanthanide complexes covalently grafted into kaolinite were thermally
more stable than the isolated lanthanide complexes. The hybrid materials
exhibited more intense Eu<sup>3+</sup> and Tb<sup>3+</sup> emissions
than the isolated complexes. The excitation spectra of the hybrid
materials showed a broad band at 277 nm, assigned to a ligand-to-metal
charge transfer, whereas the emission spectra showed bands related
to the typical electronic transitions of Eu<sup>3+</sup> and Tb<sup>3+</sup> ions from the excited states <sup>5</sup>D<sub>0</sub> and <sup>5</sup>D<sub>4</sub> to the <sup>7</sup>F<sub><i>J</i></sub> fundamental states. The (4 → 5 and 4 → 4) and (0 →
2) transitions were the most intense ones and corresponded to green
and red emissions, respectively.
2017-02-16 00:00:00
powder X-ray diffraction
Luminescence-Functionalized Clay Hybrid Materials
form dipicolinate-intercalated kaolinite
material
5 D 4
7 F J
Dipicolinate Complexes Covalently Grafted
Kaolinite
ligand-to-metal charge transfer
CHN element analysis
transition
Eu
lanthanide complexes
emission
lanthanide complexes covalently
cation
Tb
states 5 D 0
spectra