Integrated X-ray crystallography, optical and computational methods in studies of structure and luminescence of new synthesized complexes of lanthanides with ligands derived from 2,6-diformylpyridine

Oliveira, Gelson Manzoni de; Machado, Aline; Gomes, Geraldo Wachholz; Monteiro, Jorge H. S. K.; Davolos, Marian Rosaly; Abram, Ulrich; Jagst, Alexander

doi:10.1016/j.poly.2010.12.021

Cited by 15 publications

(4 citation statements)

References 33 publications

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“…For this purpose, we have chosen [Er(OH) n ] m ∓ models where the Er–O distances are kept at 2.3 Å, the O–H bond distances are fixed at 1 Å, and the Er–O–H bond angle(s) are fixed at 180° to preserve the symmetry for all of the models. We would like to note here that the models considered here are fictitious and are employed here only to probe the role of symmetry and coordination number; however, the linear coordination tested here might be achievable with ligands such as cyanides . Models studied here are shown in Figure , along with the computed g zz anisotropy axis and the energies of low-lying eight KDs for model complexes from C.N.1 to C.N.12 are provided in the Supporting Information (see Table S16).…”

Section: Resultsmentioning

confidence: 99%

Magnetic Anisotropy and Mechanism of Magnetic Relaxation in Er(III) Single-Ion Magnets

2014

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Magnetic anisotropy is a key component in the design of single-molecule magnets (SMMs) possessing a large barrier height for magnetization reversal. Lanthanide-based SMMs are the most promising candidates in this arena as they offer a large magnetic anisotropy due to the presence of strong spin-orbit coupling. Among lanthanides, Er(III) complexes are gaining attention in the area of SMMs, because of their intriguing magnetic properties and attractive blocking temperatures. Here, we have undertaken detailed ab initio calculations on four structurally diverse Er(III) SMMs to shed light on how the magnetic anisotropy is influenced by the role of symmetry and structural distortions. The employed CASSCF+RASSI calculations have offered rationale for the observed differences in the estimated Ueff values for the studied complexes and also offered hints to the mechanism of magnetic relaxation. The differences in the mechanism of magnetic relaxations are further analyzed based on the Er-ligand interactions, which is obtained by analyzing the charges, densities, luminescent behavior and the frontier molecular orbitals. Our calculations, for the first time, have highlighted the importance of high symmetry environment and ligand donor strength in obtaining large Ueff values for the Er(III) complexes. We have examined these possibilities by modeling several structures with variable coordination numbers and point group symmetry. These results signify the need of a detailed understanding on the shape of the anisotropy and the point group symmetry in order to achieve large Ueff values in Er(III) single-ion magnets.

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Section: Resultsmentioning

confidence: 99%

Magnetic Anisotropy and Mechanism of Magnetic Relaxation in Er(III) Single-Ion Magnets

2014

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“…The rest of the emission bands were small compared with the latter. It has been previously reported that these characteristics are indicative of low-symmetry Eu 3+ coordination compounds [44]. Additionally, the emission peak centered at 615 nm is the strongest one, which results in a red emission with the colorimetric coordinates (0.627, 0.342).…”

Section: Resultsmentioning

confidence: 72%

Two-Dimensional and Three-Dimensional Coordination Polymers Based on Ln(III) and 2,5-Diiodoterephthalates: Structures and Luminescent Behavior

et al. 2022

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Five new coordination polymers based on Ln3+ and 2,5-diiodoterephthalates (2,5-I-bdc)— {[La2(2,5-I-bdc)3(DMF)4]}·2DMF (1) and {[Ln2(2,5-I-bdc)3(DMF)4]} (Ln = La (2), Nd (3), Sm (4) and Eu (5))—were prepared and characterized by single crystal and powder X-ray diffractometry. Luminescent behavior was examined (the highest quantum yield is 4.5%); thermal stability was examined using thermogravimetric analysis.

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“…The 4f-4f intensity theory is widely used for lanthanide complexes. [39][40][41][42] The calculation of the intensity parameters was performed for LaOF:Eu 3+ in rhombohedral and tetragonal phases in order to compare the effects of point symmetry on Judd-Ofelt intensity parameters and the correlation with polarizability. The coordination polyhedron and spherical polar coordinates were obtained from crystallographic information 24,25 and the polar spherical coordinates for LaOF:Eu 3+ in rhombohedral and tetragonal phase are shown in Tables S1 and S2, respectively, in the ESI †.…”

Section: Resultsmentioning

confidence: 99%

Non-stabilized europium-doped lanthanum oxyfluoride and fluoride nanoparticles well dispersed in thin silica films

et al. 2012

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Well dispersed non-stabilized lanthanum oxyfluoride and fluoride nanoparticles were prepared in situ in thin silica films from rapid thermal decomposition of lanthanum tris-trifluoroacetate under nitrogen atmosphere. The thin silica films were obtained from sol-gel method and spin-coating. The spectroscopic properties of the non-stabilized nanoparticles as well the nanoparticles dispersed into thin silica films were studied in order to apply the system in future photonic applications such as erbium(III)-doped waveguide amplifiers. The non-stabilized nanoparticles were characterized by XRD, FT-IR, Transmission Electron Microscopy, Confocal Raman Spectroscopy and steady-state and timeresolved Luminescence Spectroscopy and these characterizations were used as a starting point to characterize the nanoparticles dispersed into the films. According to the temperature of the thermal treatments, the non-stabilized nanoparticles may present Eu(III)-doped LaOF in tetragonal and rhombohedral phases as well as a mixed phase of Eu(III)-doped LaF 3 and LaOF. The tetragonal LaOF phase has C 4v La(III) point symmetry and is more symmetric than the rhombohedral LaOF phase, where the La(III) ion has C 3v symmetry, consequently tetragonal LaOF presented lower U 2 values than rhombohedral LaOF. Theoretical calculations of Judd-Ofelt intensity parameters were also performed and were in good agreement with the experimental values. The samples containing the mixed phase of LaF 3 and LaOF presented lower values of intensity parameters than pure LaOF phases. The samples containing the mixed phase presented higher values of emission lifetimes and quantum efficiencies. Confocal Raman spectroscopy of these samples complements the luminescence studies and indicates which LaOF phase is present in the mixed phase of LaF 3 and LaOF. The rapid thermal decomposition of the precursor tris-trifluoroacetate on thin silica films results in well-dispersed 10 nm nanoparticles. The mixed phase of LaF 3 and LaOF phases is also present in thin films. The luminescence of the Eu(III) and Er(III)/Yb(III)-doped LaF 3 /LaOF nanoparticles containing thin silica films presented broad emission bands suggesting that in the future the systems may be applied as erbium(III)-doped waveguide amplifiers.

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Integrated X-ray crystallography, optical and computational methods in studies of structure and luminescence of new synthesized complexes of lanthanides with ligands derived from 2,6-diformylpyridine

Cited by 15 publications

References 33 publications

Magnetic Anisotropy and Mechanism of Magnetic Relaxation in Er(III) Single-Ion Magnets

Magnetic Anisotropy and Mechanism of Magnetic Relaxation in Er(III) Single-Ion Magnets

Two-Dimensional and Three-Dimensional Coordination Polymers Based on Ln(III) and 2,5-Diiodoterephthalates: Structures and Luminescent Behavior

Non-stabilized europium-doped lanthanum oxyfluoride and fluoride nanoparticles well dispersed in thin silica films

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