Περίληψη:
LnIII coordination compounds were synthesized with two benzimidazolic ligands, 2 pb = 2-(2-pyridyl)benzimidazole and 4tb = 2-(4-thiazolyl)benzimidazole, with Eu, Gd, Tb and Dy, namely: [Ln (NO3)3 (Ln)2]⋅S, where Ln = 2 pb, 4tb and S = solvent. They were characterized by IR, 1D and 2D 1H and 13C NMR, solid state UV–Vis–NIR absorption and emission and EPR spectroscopies, X-ray powder diffraction, elemental analyses, electrical conductivity and magnetic susceptibility. The compounds of EuIII with 2 pb and 4tb, TbIII and DyIII with 4tb showed luminescence at RT in the solid state; their emission life time ranged from 0.026 to 1.82 ms. 2 pb and 4tb sensitized lanthanides luminescence. Results of DFT theoretical calculations for the ligand (H2L) are used to assign the ligand singlet and triplet excited state energy levels. Additionally, a full analysis of the X-band EPR spectra in the solid state gave the following results, at 297 K for [Gd(NO3)3 (2 pb)2]·CH3COCH3, g = 1.990, |D| = 0.0687 cm−1, E = 0.0165 cm−1 and λ = |E/D| = 0.240; for [Gd(NO3)3 (4tb)2]⋅CH3COCH3, g = 2.000; |D| = 0.0670 cm−1, E = 0.000 cm−1 and λ = |E/D| = 0.000. At lower temperature, 128 K, compounds showed an increase of the rhombicity as the temperature decreased. © 2018 Elsevier B.V.
Συγγραφείς:
Olea-Román, D.
Solano-Peralta, A.
Pistolis, G.
Petrou, A.L.
Kaloudi-Chantzea, A.
Esturau-Escofet, N.
Durán-Hernández, J.
Sosa-Torres, M.E.
Castillo-Blum, S.E.
Λέξεις-κλειδιά:
Dysprosium compounds; Electron spin resonance spectroscopy; Energy transfer; Europium; Excited states; Luminescence; Magnetic susceptibility; Nuclear magnetic resonance; Rare earth elements; X ray powder diffraction, Coordination compounds; Electrical conductivity; EPR spectra; Excited-state energy; Lanthanide complex; Lifetime; Lower temperatures; Theoretical calculations, Ligands
