Electrogenerated Chemiluminescence and Electronic States of Several Organometallic Eu(III) and Tb(III) Complexes: Effects of the Ligands

• Published in: ChemistrySelect (Weinheim) 2019-03, Vol.4 (9), p.2815-2831
• Main Authors: Ishimatsu, Ryoichi, Kunisawa, Eri, Nakano, Koji, Adachi, Chihaya, Imato, Toshihiko
• Format: Article
• Language: English
• Subjects: 4 f electron; Electrochemiluminescence; Enolate; Photophysical properties; β-diketone
• ISSN: 2365-6549; 2365-6549
• DOI: 10.1002/slct.201900595

We report the electrochemical properties, and electrogenerated chemiluminescence (ECL) of eight different organometallic complexes of Eu(III) and Tb(III), Eu(dbm)3phen, Eu(dbm)3bath, Eu(fod)3phen, Eu(tta)3phen, Tb(acac)3phen, Tb(acac)3bath, Tb(fod)3phen, and Tb(tmhd)3bpy in acetonitrile, where phen, bath, and bpy are 1, 10‐phenanthroline, bathophenanthroline, 2,2′‐bipyridyl, respectively, and the anionic ligands, acac−, dbm−, fod−, and tta− are the enolate forms of acetylacetone, dibenzoylmethanate, 6,6,7,7,8,8,8‐heptafluoro‐2,2‐dimethyl‐3,5‐octanedione, and thenoyltrifluoroacetone, respectively. The electronic states of the neutral and some charged states of the complexes were clarified with density functional theory calculations. The ECL spectra were recorded by using S2O82− as a coreactant, and for all complexes, sharp ECL spectra, which are attributable to the f‐f transitions, were observed. On the potential‐dependent ECL spectra, broad ECLs, which were originated from the ligands, were also detected. Based on the ECL behavior and the electronic states, the mechanisms of the intraconfigurational ECL were discussed. ECLs based on the intraconfigurational f‐f transitions of several Eu(III) and Tb(III) complexes are described. The ECLs of the complexes were generated by using S2O82− as a coreactant. By considering the electronic states of the complexes estimated with the density functional theory calculations, and the potential dependent ECL spectra, possible ECL mechanisms based on the intraconfigurational f‐f transitions are proposed.