Polyphenylcyclopentadienyl Ligands as an Effective Light-Harvesting π-Bonded Antenna for Lanthanide +3 Ions

Abstract

A new approach to design "antenna-ligands" to enhance the photoluminescence of lanthanide coordination compounds has been developed based on a π-type ligand-the polyphenyl-substituted cyclopentadienyl. The complexes of di-, tri-, and tetraphenyl cyclopentadienyl ligands with Tb and Gd have been synthesized and all the possible structural types from mononuclear to di- and tetranuclear complexes, as well as a coordination polymer were obtained. All types of the complexes have been studied by single-crystal X-ray diffraction and optical spectroscopy. All terbium complexes are luminescent at ambient temperature and two of them have relatively high quantum yields (50 and 60%). Analysis of energy transfer process has been performed and supported by quantum chemical calculations. The role of a low-lying intraligand charge transfer state formed by extra coordination with K in the Tb ion luminescence sensitization is discussed. New aspects for design of lanthanide complexes containing π-type ligands with desired luminescence properties have been proposed.

Diarylphosphate as a New Route for Design of Highly Luminescent Ln Complexes

“…In this case, the estimated E 2 value is near to limit and influence of BET process cannot be excluded. Previously BET influence on energy transfer process was demonstrated even at E 2 ~2489 cm −1 [ 29 ].…”

The structural diversity of heterocycle-fused potassium cyclopentadienides

“…Potassium salts were obtained from corresponding heterocyclefused cyclopentadienes 1-4 by metallation with benzyl potassium in THF medium. This efficient method of metallation of substituted cyclopentadienes, which we recently proposed, [33][34][35] signicantly increased the availability of potassium derivatives that are synthetic precursors of cyclopentadienyl complexes. Crystalline salts 5-8 were obtained by slow ($1 week) diffusion of n-hexane into solutions of metallation products in THF (5) or in THF/diglyme mixture (for 6-8, see Scheme 4).…”

Bis[μ-bis(2,6-diisopropylphenyl) phosphato-κ2 O:O′]bis[(2,2′-bipyridine-κ2 N,N′)lithium] toluene disolvate and its catalytic activity in ring-opening polymerization of ∊-caprolactone and L-dilactide

“…The presence of the MeOH molecules and therefore undesirable Ln-O-H bonds usually noticeably decreases the quantum yield because of quenching luminescence (Bü nzli & Piguet, 2005;Bü nzli, 2017;Yan et al, 1995;Sy et al, 2016). At the same time, the phosphate ligand in the complexes has not displayed properties of an 'antenna' ligand for luminescence sensitization (Bü nzli & Piguet, 2005;Bü nzli et al, 2007;Sy et al, 2016;Guillou et al, 2016;Hewitt & Butler, 2018;Roitershtein et al, 2018). A 2,2 0 -bipyridine (bipy) molecule can serve as such an 'antenna', which usually increases the quantum yield dramatically.…”