Theoretical and Experimental Spectroscopic Approach of Fluorinated Ln(3+)-beta-Diketonate Complexes

authors	dos Santos, ER; Freire, RO; da Costa, NB; Paz, FAA; de Simone, CA; Junior, SA; Araujo, AAS; Nunes, LAO; de Mesquita, ME; Rodrigues, MO
nationality	International
journal	JOURNAL OF PHYSICAL CHEMISTRY A
keywords	RARE-EARTH IONS; LUMINESCENCE QUANTUM YIELD; NUCLEAR MAGNETIC-RESONANCE; 2D COORDINATION POLYMERS; BETA-DIKETONE COMPLEXES; ENERGY-TRANSFER PROCESS; SPARKLE MODEL; INTENSITY PARAMETERS; EUROPIUM COMPLEX; METAL-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 Eu3+ cation is coordinated to three fod anionic ligands and to one phen. The symmetry around Eu3+ 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-D-5(4) resonance, which contributes significantly to the nonradiative deactivation of Tb3+, 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)(H2O)(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.
publisher	AMER CHEMICAL SOC
issn	1089-5639
year published	2010
volume	114
issue	30
beginning page	7928
ending page	7936
digital object identifier (doi)	10.1021/jp104038r
web of science category	Chemistry, Physical; Physics, Atomic, Molecular & Chemical
subject category	Chemistry; Physics
unique article identifier	WOS:000280360800013