Chiroptical Spectra of a Series of Tetrakis((+)-3-heptafluorobutylyrylcamphorato)lanthanide(III) with an Encapsulated Alkali Metal Ion: Circularly Polarized Luminescence and Absolute Chiral Structures for the Eu(III) and Sm(III) Complexes

Abstract

The luminescence and circularly polarized luminescence (CPL) spectra of MI[Eu((+)–hfbc)4] show a similar behavior to the exciton CD in the intraligand π–π* transitions when the alkali metal ions and solvents are manipulated. There is a difference in susceptibility in solvation toward the alkali metal ions but not toward the Eu(III) ion, as in the case of axially symmetric DOTA–type compounds. The remarkable CPL in the 4f–4f transitions provide much more information on stereospecific formation of chiral Eu(III) complexes, since CPL spectroscopy is limited to luminescent species and reflects selectively toward helicity of the local structural environment around the lanthanide(III). While in comparison, exciton CD reveals the chiral structural information from the helical arrangement of the four bladed chelates. Of special importance, the observation of the highest CPL activities measured to date for lanthanide(III)–containing compounds (i.e. Eu and Sm) in solution supports that the chirality of Lanthanide(III) in the excited state corresponds to that in the ground state, which was derived from the exciton CD.

Chiroptical Properties of Nonanuclear Tb(III) Clusters with Chiral Champhor Derivative Ligands

“…1) [26]. These ligands are champhor derivatives for enhancement of g CPL according to the previous report [27]. We have demonstrated the intense CPL and electronic structures of Tb(III) clusters with bornyl salicylates, Tb-(±)-bor.…”

Lanthanide complexes as chiral probes exploiting circularly polarized luminescence

“…93 The emission dissymmetry factor at 595 nm 73 Notwithstanding the fact that this lanthanide system is inherently unsuitable for application in biological systems due to a lack of aqueous solubility, this example helps to illustrate the importance of gaining as much understanding as possible of the origin of observed CPL modulation in systems that are to be developed for use as optical probes.…”

Highly Circularly Polarized Electroluminescence from a Chiral Europium Complex

“…For this prototype device, the Ln(III) complex CsEu(hfbc) 4 (hfbc = 3-heptafl uoro-butylyrylcamphorate; Figure 2 a), with the highest available CPPL ( g PL = 1.38 at 595 nm, meaning a I L / I R ratio of 85:15) for a lanthanide system, [ 21 ] was selected as the chiral emitter. Even though it has a low PL quantum yield (3% as powder), for our purposes, it provides a very good tradeoff between polarization and total luminescence.…”

“…[ 21 ] This excludes all artifacts due to linear polarization and birefringence of any component in both OLEDs and detection apparatus. It further ensures that the observed CPEL is Eu(III)-centered, ruling out any contribution of the polymeric matrix to the measured EL and CPEL.…”