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Luminescence properties of the Ln–EDTA complexes covalently linked to the chitosan biopolymers containing β‐diketonate as antenna ligands
Author(s) -
Costa Israel F.,
Pires Gilvan P.,
Espínola José Geraldo P.,
Brito Hermi F.,
Felinto Maria Claudia F.C.,
Faustino Wagner M.,
Teotonio Ercules E.S.
Publication year - 2020
Publication title -
luminescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 45
eISSN - 1522-7243
pISSN - 1522-7235
DOI - 10.1002/bio.3735
Subject(s) - epichlorohydrin , chitosan , antenna effect , photoluminescence , luminescence , biopolymer , ligand (biochemistry) , covalent bond , hybrid material , materials science , ion , chemistry , polymer , photochemistry , polymer chemistry , nanotechnology , organic chemistry , optoelectronics , biochemistry , receptor
This paper reports on the preparation, characterization, and photoluminescence properties of novel hybrid materials, in which the EDTA–Ln–L complexes (where L: H 2 O, acac, bzac, dbm, and tta ligands, and Ln: Eu, Gd, and Tb) were covalently linked to the precursor medium molecular weight chitosan surface (CS) matrices or on the chitosan surfaces previously crosslinked with epichlorohydrin (CSech). The emission spectra of these materials were characterized by intraconfigurational‐4fN transitions centred on the Eu 3+ and Tb 3+ ions. Some broad bands from the polymeric matrix were also observed in the emission spectra, however the relative intensities of the intraconfigurational bands increased significantly for systems containing diketonate ligands when the antenna effect became more efficient. The values of the radiative rates (A rad ) were higher for crosslinked hybrid systems with epichlorohydrin, while nonradiative rates (A nrad ) presented the opposite behaviour. These data contributed to an increase in the values of emission quantum efficiency (η) for crosslinked materials. The effect of the modification process and antenna ligand on the values of intensities, intensity parameters Ω 2 e Ω 4 of the Eu 3+ complexes were also investigated. The results showed that the crosslinked biopolymer surfaces have great potential for applications in molecular devices light converters.