Circularly Polarised Luminescence in Enantiopure Samarium and Europium Cryptates

Abstract

Circularly polarised luminescence (CPL) is a chiroptical phenomenon gaining more and more attention, as the availability of the necessary spectrometers is getting better and first applications in bioimaging or for the preparation of OLEDs (organic light emitting diodes) are coming within range. Until now most examples of distinctly CPL-active compounds were europium and terbium complexes though theoretically the electronic structure of samarium should be as suitable as the one of terbium. This discrepancy can be accounted for by the high susceptibility of samarium to non-radiative deactivation processes. The aim of this study was to strategically circumvent this difficulty by the use of a ligand scaffold which has already proven to efficiently suppress these processes, namely the cryptates. The prepared partly deuterated samarium and europium complexes exhibit distinct circularly polarised luminescence with dissymmetry factors up to g =+0.13 (Sm ) or g =-0.19 (Eu ).

Circularly polarized luminescence of Sm (III) and Eu (III) complexes with chiral ligand (R/S)‐BINAPO

“…These promising CPL results for Sm((R/S)-BINAPO) 2 (OTf) 3 are unlikely to be unique to the BINAPO ligand. The data in this study combined with those of some other recent studies 30,31,35,36 should encourage more exploration of chiral Sm 3+ complexes for CPL applications.…”

“…The dynamic coupling mechanism involves coupling a metal-centered 4f-4f electric multipole (eg, quadropole) transition with ligand-centered electric dipole moment transitions (eg, π → π* transitions). [30][31][32][33][34][35][36] This is somewhat surprising given the fact that there are two magnetic-dipole allowed emissive transitions, 4 G 5/2 → 6 H 5/2 and 4 G 5/2 → 6 H 7/2 , within the 4f 5 configuration of Sm 3+ . The 5 D 0 → 7 F 1 transition within the 4f 6 configuration of Eu 3+ is an example of a magnetic dipole allowed transition that typically leads to large emission dissymmetry factors, g em .…”

“…4,21,22,24,25,28,29 While Eu 3+ has been widely exploited for CPL applications, there are very few studies involving the CPL of Sm 3+ complexes. [30][31][32][33][34][35][36] This is somewhat surprising given the fact that there are two magnetic-dipole allowed emissive transitions, 4 G 5/2 → 6 H 5/2 and 4 G 5/2 → 6 H 7/2 , within the 4f 5 configuration of Sm 3+ .…”

Luminescence, chiroptical, magnetic andab initiocrystal-field characterizations of an enantiopure helicoidal Yb(iii) complex

“…28 Th e other one that uses a standard photoelastic modulator and a single channel detector , is less resolved but can be used down to 1500 nm . 29 It is worth noting that NIR-chiroptical measurements are relatively rare 30 compared to visible ones that are widely e xemplified for europium(III), terbium(III) and samarium(III) chiral complexes.Erreur ! Argument de commutateur inconnu.…”

Luminescence, Chiroptical, Magnetic and Ab-Initio Crystal-Field Characterizations of an Enantiopure Helicoidal Yb(III) Complex: The Van Vleck Rennaissance

“…28 The other one that uses a standard photoelastic modulator and a single channel detector, is less resolved but can be used down to 1500 nm. 29 It is worth noting that NIR-chiroptical measurements are relatively rare 30 compared to visible ones that are widely exemplified for europium(III), terbium(III) and samarium(III) chiral complexes.Erreur ! Argument de commutateur inconnu.…”