abstract
In this work, the coordination compounds presenting the formulas [Eu(acac)(NO3)(2) (phen)(2)]center dot H2O (Eu1) and [Eu(bzac)(NO3)(2)(phen)(2)]center dot H2O (Eu2), acac: acetylacetonate, bzac: benzoylacetonate and, phen: 1,10-phenantroline, were successfully synthesized and some spectroscopic properties were investigated by theoretical and experimental methods. These compounds were characterized via elemental analysis, FTIR spectroscopy and thermogravimetric analysis (TGA). The X-ray diffraction data revealed that the compound Eu1 crystallizes in the monoclinic space group P2/n. Spectroscopic data showed that ligand-to-metal charge transfer states (LMCT) in the [Eu(beta-dik)(NO3)(2)(phen)(2)]center dot H2O complexes (beta-dik: acac or bzac) are redshift as compared with [Eu(beta-dik)3(phen)] complexes. These data showed that LMCT states play the most important role on the luminescence quenching in the complexes Eu1 and Eu2, which only exhibit high luminescence intensities at low temperatures. Furthermore, the role of changes in the chemical environment on the intensity parameters Omega(lambda) (lambda = 2 and 4) have been investigated from the theoretical point of view for the complexes Eu1 to Eu2, and from these to tris beta-dik complexes. Interestingly, the theoretical intensity parameters ratio Omega(2)/Omega(4) calculated are in a good agreement with those experimental ones.
keywords
INTRAMOLECULAR ENERGY-TRANSFER; CHARGE-TRANSFER STATE; CRYSTAL-STRUCTURE; INTENSITY PARAMETERS; LANTHANIDE COMPLEXES; ELECTRONIC-STRUCTURE; DESIGN; TRANSITIONS; ABSORPTION; SPECTRA
subject category
Optics
authors
Santos, PRS; Pereira, DKS; Costa, IF; Silva, IF; Brito, HF; Faustino, WM; Neto, ANC; Moura, RT; Araujo, MH; Diniz, R; Malta, OL; Teotonio, EES
our authors
Albano Neto Carneiro Neto
Junior Researcheracknowledgements
The authors are grateful for the financial support from the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES), the Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) and the Financiadora de Inovacao e Pesquisa (FINEP). The Fundacao de Amparo a Pesquisa do Estado de Minas Gerais (FAPEMIG). This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology/MCTES and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. ANCN thanks SusPhotoSolutions project, CENTRO-01-0145-FEDER-000005, Portugal for his grant.