Circularly polarized luminescence of Eu(III) complexes with chiral 1,1′‐bi‐2‐naphtol‐derived bisphosphate ligands

Abstract

The interest for lanthanide circularly polarized luminescence (CPL) has been quickly growing for 10 years. However, very few of these studies have involved correlation between the dissymmetry factor (g lum ) and the chemical modifications in a series of chiral ligands. Four polymeric compounds of Eu(III) were prepared by using a series of binaphtyl derivatives for which the size of the π system as well as the number of stereogenic elements (i.e., the binaphtyl moiety) are modulated. The resulting {[Eu(hfac) 3 ((S)/(R)-L x )]} n (x = 1 and 3) and {[Eu(hfac) 3 ((S,S,S)/(R,R,R)-L x )]} n (x = 2 and 4) have been characterized by powder X-ray diffraction by comparison with the X-ray structures on single crystal of the Dy(III) analogs. In solution, the structure of the complexes is deeply modified and becomes monomeric. The nature of the ligand induces change in the shape of the CPL spectra in CH 2 Cl 2 solution. Furthermore, a large jg lum j = 0.12 of the magnetic-dipole transition for the [Eu(hfac) 3 ((S,S,S)/ (R,R,R)-L 2 )] complex involving the ligand with three stereogenic elements and an extended π system has been measured. This report also shows CPL measurements in solid state for the series of {[Eu(hfac) 3 ((S)/(R)-L x )]} n (x = 1 and 3) and {[Eu(hfac) 3 ((S,S,S)/(R,R,R)-L x )]} n (x = 2 and 4) polymers.

Luminescent and Sublimable Binaphthyl-Based Field-Induced Lanthanide Single-Molecule Magnets

“…The ratio R of the intensities of the 5 D 0  7 F 1 and 5 D 0  7 F 2 transitions (R = I( 5 D 0  7 F 2 )/I( 5 D 0  7 F 1 )) is found equal to 24.6 units. This value is close to those found for Eu III compounds involving chiral 1,1'-bi-2-naphthol-derived bisphosphate ligands [36]; moreover a value of R > 10 is often observed for Eu III -diketonate complexes [37]. The emission lifetime curves can be fit with a mono-exponential decay function affording lifetime constants around 700 s at both room temperature and 77 K (Figure S10).…”

“…Recording the spectrum at 77 K allows for a slightly better resolution compared to the room temperature measurement. The 5 D 0  7 F 0 transition can be observed and the 5 D 0  7 F 1 and 5 D 0  7 F 2 transitions are split in three and at least four signals, respectively, which are higher numbers than observed for perfect D 4d symmetries [36]. The ratio R of the intensities of the 5 D 0  7 F 1 and 5 D 0  7 F 2 transitions (R = I( 5 D 0  7 F 2 )/I( 5 D 0  7 F 1 )) is found equal to 24.6 units.…”

Circularly polarized luminescence from Tb(iii) interacting with chiral polyether macrocycles

“…The study of chiral lanthanide complexes is a strong and developing field of research. 1–26 These complexes often display interesting circularly polarized luminescence (CPL) properties and, 27 for this reason, applications can be found in key research areas such as in bioanalytical assays and imaging 28–39 or circularly polarized OLEDs. 40–44 To promote efficient chiroptical properties, polydentate monoligands, such as triazacyclononane or tetraazacyclododecane, are usually employed.…”

Theoretical and experimental analysis of circularly polarized luminescence spectrophotometers for artifact-free measurements using a single CCD camera.

“…These theoretical finding are experimentally illustrated in the second part of the paper, on broad (∼ 50 nm) and narrow line (∼ 1 nm) spectra from camphorquinone and Eu 3+ complexes , respectively. Moreover, in order to assess the limits of our method and to verify its performance, we compare the spectra obtained with the camera to those obtained with our "home-made" single channel PEM based setup described elsewhere [7,22,23].…”