abstract
This work reports the structural characterization and photophysical properties of Dy-III, Tb-III, and Eu-III coordination polymers with two phenoxo-triazole-based ligands [2,6-di(1H-1,2,4-triazole-1-yl-methyl)-4-R-phenoxo, L (R) Tr (R = CH3; Cl)]. These ligands permitted us to obtain isostructural polymers, described as a 1D double chain, with Ln(III) being nona-coordinated. The energies of the ligand triplet (T-1) states were estimated using low-temperature time-resolved emission spectra of Y-III analogues. Compounds with (LTr)-Tr-Cl present higher emission intensity than those with (LTr)-Tr-Me. The emission of Tb-III compounds was not affected by the different excitation wavelengths used and was emitted in the pure green region. In contrast, (DyLTr)-Tr-Me emits in the blue-to-white region, while the luminescence of (DyLTr)-Tr-Cl remains in the white region for all excitation wavelengths. On the other hand, Eu-III compounds emit in the blue (ligand) or red region (Eu-III) depending on the substituent of the phenoxo moiety and excitation wavelength. Theoretical calculations were employed to determine the excited states of the ligands by using time-dependent density functional theory. These calculations aided in modeling the intramolecular energy transfer and rationalizing the optical properties and demonstrated that the sensitization of the Ln(III) ions is driven via S-1 -> Ln(III), a process that is less common as compared to T-1 -> Ln(III).
keywords
INTRAMOLECULAR ENERGY-TRANSFER; METAL-ORGANIC FRAMEWORKS; AB-INITIO PSEUDOPOTENTIALS; WHITE-LIGHT EMISSION; LANTHANIDE AQUO IONS; CHARGE-TRANSFER; PHOTOPHYSICAL PROPERTIES; EFFICIENT SENSITIZATION; ABSORPTION INTENSITIES; EUROPIUM COMPLEX
subject category
Chemistry
authors
Manzur, J; Fuentealba, P; Gil, Y; Pérez-Obando, J; Alfaro, JM; Carvallo, AIV; Aravena, D; de Santana, RC; Neto, ANC; Spodine, E
our authors
Albano Neto Carneiro Neto
Junior ResearcherProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
Other
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Mediaacknowledgements
E.S., J.M., P.F., J.M.A., and A.V. acknowledge financial support from FONDECYT 1200033 grant. This study was financed in part by the Brazilian agencies, Conselho Nacional de Desenvolvimento Cientiifico e Tecnologico (CNPq, 427164/2018-4), and Fundacao de Amparo a Pesquisa do Estado de Goias (FAPEG). RCS thanks the CNPq research fellowship 310,307/2021-0. Powered@NLHPC: this research was partially supported by the supercomputing infrastructure of the NLHPC (ECM-02). This work was developed within the scope of the projects CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020, and LA/P/0006/2020, The Shape of Water (PTDC/NAN-PRO/3881/2020), and LogicALL (PTDC/CTM-CTM/0340/2021), financed by national funds through the FCT/MCTES (PIDDAC).