Correlation between structural data and spectroscopic studies of a new β-diketonate complex with trivalent europium and gadolinium

Abstract

This paper reports the study of structural and luminescence parameters of a seven-coordination compound containing b-diketone butyl methoxy-dibenzoyl-methane (bmdm) and triphenylphosphine oxide (tppo), both acting as antennae. The complex was obtained by substitution of water molecules in the [RE(bmdm) 3 (H 2 O) 2 ] precursor, where RE = Eu 3+ or Gd 3+ . The structural data determined by X-ray monocrystal diffraction reveal that the compound crystallizes in a triclinic space group P 1 and the coordination polyhedron is near a capped trigonal prism, with a symmetry site near a C 2v point group. The ground state geometry was determined using Sparkle/AM1 implemented in mopac2009 software, and compared with that obtained by monocrystal. The triplet (T) and singlet (S) levels were determined using INDO/S-CIS implemented in the Zindo software, the results obtained are very close to the experimental measurements. The intensity parameters O 2 and O 4 were calculated from emission spectrum. The high value of the O 2 parameter (37.2 Â 10 À20 cm 2 ) shows a highly polarizable environment around the europium ion and a high degree of covalence between the ligand and metal, showing that tppo molecules contribute to an increase in the covalence between the metal and ligand. The transfer rates show a predominance in the transfer process when compared with back transfer ones, with the main channel of transfer processes: T

Estimating the Individual Spectroscopic Properties of Three Unique EuIII Sites in a Coordination Polymer

“…To estimate energy-transfer rates between donor and acceptor with the approach proposed by Malta in 2008, we did not consider the pathway through the singlet state of the ligand because of its small contribution. , Instead, only the energy-transfer rates for the pathways T → 5 D 1 and T → 5 D 0 were calculated (Table ). We observed that the rates of energy-transfer rates are at least 7 orders of magnitude faster than the energy back-transfer rates, which is consistent with the energy gap in excess of 3000 cm –1 between triplet and 5 D 1,0 levels, which effectively prevents energy back-transfer .…”

“…Nonetheless, syntheses are often cumbersome, and thus routine screening of large numbers of sensitizers is time consuming. On the other hand, theoretical methods can aid in designing and evaluating the best system for a given application. − The development of user friendly software packages such as LUMPAC has increased the popularity of theoretical methods among traditionally experimental research groups to explain experimental observations − and predict structural and optical properties . The ideal theoretical method should precisely estimate bond lengths and symmetry around the Ln III , as the latter correlates with the photophysical properties. , The Judd–Ofelt (JO) intensity parameters, , which describe the symmetry around the Ln III , ,,,, can be determined experimentally and also calculated and are therefore a good benchmark for the quality of the modeling.…”

“…However, when the system has two or more unique Eu III coordination sites, this procedure leads to inconsistent results because the experimental JO intensity parameters cannot be determined for each unique metal ion and its coordination polyhedron and this fact precludes the individual theoretical adjustment. Thus, the known theoretical studies involve monometallic complexes. , While Wen et al successfully used complete-active-space self-consistent field energies and wave functions to extract the crystal-field parameters of Ce III in solids and molecules, the analysis of larger systems requires long computation times and therefore examples of systems containing more than one unique Ln III , such as some dimers or coordination polymers, remain scarce. , …”

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

“…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 †.…”

Recent advances in lanthanide spectroscopy in Brazil

“…Other investigations reporting the use and/or development of theoretical models or methodologies have been discussed in the literature [8,12,13,15,17,28,43,55,56,86,[199][200][201][202][203][204][205][206][207].…”