Striking solvent dependence of total emission and circularly polarised luminescence in coordinatively saturated chiral europium complexes: solvation significantly perturbs the ligand field

Abstract

Examination of total emission and circularly polarised luminescence (CPL) spectra of three 9-coordinate Eu(III) complexes with well-defined speciation shows that the ligand fields of these C3 symmetric complexes are extremely...

Near Infrared Circularly Polarized Luminescence From Water Stable Organic Nanoparticles Containing a Chiral Yb(III) Complex

“…It is therefore not surprising that [Eu L (tta) 2 (H 2 O)]CF 3 SO 3 complex can completely loose the CPL activity once its surroundings move from the DCM solvent to the PLGA polymer. Similar effect of solvation on the CPL activity of coordinatively saturated chiral Eu(III) complexes has been recently reported by D. Parker et al [15] …”

“…It is therefore not surprising that [EuL(tta) 2 (H 2 O)]CF 3 SO 3 complex can completely loose the CPL activity once its surroundings move from the DCM solvent to the PLGA polymer. Similar effect of solvation on the CPL activity of coordinatively saturated chiral Eu(III) complexes has been recently reported by D. Parker et al [15] As for the strategy to make the [YbL(tta) 2 ]•CH 3 COO molecule stable in aqueous solution, we prepared a nanoformulation in which this complex is embedded in PLGA by means of a modified nanoprecipitation method at 20 °C. [16] The obtained NPs show a monodispersed distribution of the size.…”

“…Although the reasons behind this increase are not clear, we can hypothesize that the difference in medium polarity in the two cases affects the ligand field parameters and mainly the angle θ between the electric ( μ ) and magnetic ( m ) transition dipole moments ($${{{\rm g}}_{{\rm l}{\rm u}{\rm m}}\approx 4{{\left|{\bf m}\right|}\over{\left|{\bf \mu }\right|}}{\rm cos}{\rm \theta }}$$ ), resulting in a significant change in the g‐factor [15] . To further complicate the picture, we should note that the single emergent CPL band is actually a convolution of at least 4 transitions (in a C 1 symmetry).…”

Circularly polarized activity from two photon excitable europium and samarium chiral bioprobes

“…In general, even though for each transition the CPL sign of the different crystal field components does not change with the solvent employed, the pattern recorded in methanol looks more complex. This behaviour can find a possible explanation taking into account the effect of the inner sphere solvent coordination or the overall solvation as recently discussed by D. Parker et al 91 Similarly, in addition to the solvent, other achiral entities can affect the CPL activity of the Ln(III), such as the counterion 87 and the matrix hosting the complex. 92…”

Circularly polarised luminescence laser scanning confocal microscopy to study live cell chiral molecular interactions

“…NMP was selected because NMP is structurally almost identical to the monomer unit of PVP polymers (N-Vinylpyrrolidone). This is crucial because it has recently been reported that CPL signal intensity and even CPL sign may vary as a function of solvent or medium polarity 32 . We found that the CPL signal intensity (| g em | and CPB) and sign were unaltered and the 2PE cross-section of Eu:L1 was even slightly enhanced in NMP ( σ 2 = 73 ± 3 GM for Λ- and Δ-enantiomer) compared to MeOH ( σ 2 = 51 ± 3 GM for Λ- and Δ-enantiomer), validating our choice of host polymer for spin-coated test targets.…”