Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln³⁺−β-Diketonate Complexes

Abstract

In this paper we report the synthesis of two new complexes, [Eu(fod)(3)(phen)] and [Tb(fod)(3)(phen)] (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octadionate and phen = 1,10-phenanthroline), and their complete characterization, including single-crystal X-ray diffraction, UV-vis spectroscopy, IR spectroscopy, and TGA. The complexes were studied in detail via both theoretical and experimental approaches to the photophysical properties. The [Eu(fod)(3)(phen)] complex crystallizes in the monoclinic space group P2(1)/c. The crystal structure of [Eu(fod)(3)(phen)] exhibits an offset pi-pi stacking interaction between the phenanthroline ligands of adjacent lanthanide complexes. The Eu(3+) cation is coordinated to three fod anionic ligands and to one phen. The symmetry around Eu(3+) is best described as a highly distorted square antiprism. The molar absorption coefficients of [Eu(fod)(3)(phen)] and [Tb(fod)(3)(phen)] revealed an improved ability to absorb light in comparison with the stand-alone phen and fod molecules. [Tb(fod)(3)(phen)] emits weak UV excitation, with this feature being explained by the triplet-(5)D(4) resonance, which contributes significantly to the nonradiative deactivation of Tb(3+), causing a short lifetime and low quantum yield. The intensity parameters (Omega(2), Omega(4), and Omega(6)) of [Eu(fod)(3)(phen)] were calculated for the X-ray and Sparkle/AM1 structures and compared with values obtained for [Eu(fod)(3)(H(2)O)(2)] and [Eu(fod)(3)(phen-N-O)] (phen-N-O = 1,10-phenanthroline N-oxide) samples. Intensity parameters were used to predict the radiative decay rate. The theoretical quantum efficiencies from the X-ray and Sparkle/AM1 structures are in good agreement with the experimental values, clearly attesting to the efficacy of the theoretical models.

Synthesis, structure and optical properties of two novel luminescent polar dysprosium metal–organic frameworks: [(CH3)2NH2][Dy(HCOO)4] and [N2H5][Dy(HCOO)4]

“…And few intensity parameters are available for rare earth complexes in hybrid organic-inorganic composite materials. [63][64][65][66] Judd-Ofelt phenomenological intensity parameters Ω λ determined by a least-squares fitting approach for HYD-Dy crystal are as follows: Ω 2 = 25.20 (10 -20 cm -1 ), Ω 4 = 3.93 (10 -20 cm 2 ) and Ω 6 = 4.20 (10 -20 cm -1 ). We cannot compare the Ω λ values obtained by us for HYD-Dy with data of other metal-organic compounds since, to our best knowledge, such data were not reported for Dy(III)-based MOFs.…”

“…The extraordinary high value of Ω 2 was previously reported also for other organic-inorganic complexes such as [Eu(fod) 3 (phen)] (19.00 x 10 -20 cm 2 ) and [Eu(fod) 3 (phen-N-O] (24.50 x 10 -20 cm 2 ). 64 This behavior was explained by the anisotropic features of the metal-ligand bonds and prominent dynamic coupling associated with the ligand ion polarizability. 64 Using the derived Ω λ parameters, the radiative transition rates A rad from the 4 F 9/2 level to the 6 F J and 6 H J manifolds were calculated according to relation:…”

“…64 This behavior was explained by the anisotropic features of the metal-ligand bonds and prominent dynamic coupling associated with the ligand ion polarizability. 64 Using the derived Ω λ parameters, the radiative transition rates A rad from the 4 F 9/2 level to the 6 F J and 6 H J manifolds were calculated according to relation:…”

Europium complexes: choice of efficient synthetic routes from RM1 thermodynamic quantities as figures of merit

“…15 Syntheses of lanthanide complexes are frequently carried out by means of ligand displacement reactions. In particular, ternary b-diketonate europium complexes [Eu(b) 3 (L) 2 ], where L stands for a non-ionic ligand, can be prepared by the usual synthetic route: 12,13,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]…”

Kinetic study of thermal decomposition of new Eu(III), Tb(III) and Gd(III) complexes with beta-diketone ligands and 4,4-diphenyl-2,2-dipyridyl, chloride of 1,10-phenantrolinium

“…All reagents were used as received. The complexes Eu(fod) 3 ·L and Tb(fod) 3 ·L were synthesized in ethanolic medium for 24 h. Details about the synthesis procedure have already been published elsewhere [28][29][30]. The complexes of Gd 3+ ion coordinated to phenCl and/or diphenylbipy as ligands were obtained by the slow addition of fod (0.3622 mmol/L and/or 0.4527 mmol/L) into an ethanolic suspension of gadolinium chloride.…”