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Luminescent Eu III Complexes Immobilized on a Vermiculite Clay Surface
Author(s) -
Silva Haryane R. M.,
Fonseca Maria G.,
Espínola José Geraldo P.,
Brito Hermi F.,
Faustino Wagner M.,
Teotonio Ercules E. S.
Publication year - 2014
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201301494
Subject(s) - vermiculite , chemistry , quantum yield , dibenzoylmethane , leaching (pedology) , nitric acid , photoluminescence , luminescence , inorganic chemistry , yield (engineering) , hybrid material , analytical chemistry (journal) , nuclear chemistry , fluorescence , materials science , organic chemistry , physics , environmental science , optoelectronics , quantum mechanics , soil science , metallurgy , composite material , soil water
Vermiculite clays were leached with nitric acid and functionalized with (3‐chloropropyl)trimethoxysilane. The resulting materials were modified with the methylimidazolium (MID) group to yield cationic surfaces. These materials were characterized by infrared spectroscopy, elemental analyses, and specific surface area. Tetrakis(β‐diketonate)europate(III) complexes, [EuL 4 ] – [L = dibenzoylmethane (DBM) and thenoyltrifluoroacetone (TTA)], were immobilized on the vermiculite surface containing the imidazolium cation to yield hybrid surfaces named V x ‐MID‐EuL 4 ( x = 0, 1, and 2), in which x represents the acid nitric concentration in mol L –1 that is used in the leaching process. The highest luminescence intensities of the intraconfigurational‐4f 5 D 0 → 7 F J transitions (for which J = 0, 1, 2, 3, and 4) arising from [EuL 4 ] – complexes were presented by the hybrid materials containing the amount of imidazolium cation, which depend on the leaching process. The excitation and emission spectra suggested an efficient intramolecular energy‐transfer process from ligand‐to‐Eu 3+ ion in the supported materials. The photoluminescent properties of the hybrid materials were investigated based on the emission quantum efficiency ( η ), experimental intensity parameters Ω 2 and Ω 4 , and Einstein's emission coefficient ( A 0 J ). The values of these parameters for the V 2 ‐MID‐EuL 4 surface are close to those assigned to the [EuL 4 ] – isolated complexes, which indicates that hybrid vermiculite materials are promising red phosphors.