Dinuclear enantiopure Ln complexes with (-) and (-) 2-phenylbutyrate ligands. Luminescence, CPL and magnetic properties.

The reaction of Ln(NO)·6HO (Ln = Nd, Sm, Eu, Tb, Dy, Tm and Yb) with the respective enantiopure ()-(-)-2-phenylbutyric or ()-(+)-2-phenylbutyric acid (/-2-HPhBut) and 4,7-diphenyl-1,10-phenanthroline (Bphen) allows the isolation of chiral dinuclear compounds of the formula [Ln(μ-/-2-PhBut)(/-2PhBut)(Bphen)] where Ln = Nd (R/S-Nd-a), Sm (R/S-Sm-a), Eu (R/S-Eu-a), Tb (R/S-Tb-a and R/S-Tb-b), Dy (R/S-Dy-a and R/S-Dy-b), Tm (R/S-Tm-b) and Yb (R/S-Yb-b). Single crystal X-ray diffraction was performed for compounds S-Eu-a and S-Tm-b. Powder crystal X-ray diffraction was performed for all complexes. From the crystallographic data two different structural motifs were found which are referred to as structure type and structure type . In structure type , the Ln atoms are bridged through four or -2-PhBut ligands with two different kinds of coordination modes whereas in structure type the two Ln atoms are bridged through four or -2-PhBut ligands showing only one kind of coordination mode. For those lanthanide ions exhibiting both structure types, Tb and Dy, a difference in the luminescence and magnetism behavior is observed. All compounds (except R/S-Tm-b) exhibit sensitized luminescence, notably the Eu and Tb analogues. Circular Dichroism (CD) and Circular Polarized Luminescence (CPL) in the solid state and in 1 mM dichloromethane (DCM) solutions are reported, leading to improved chiroptical properties for the DCM solutions. The asymmetry factor () in 1 mM DCM is ±0.02 (+ for R-Eu-a) for the magnetically allowed transition D → F and ±0.03 (+ for R-Tb-a and R-Tb-b) for the D → F transition. Magnetic properties of all compounds were studied and the Dy compound with the structural motif (R-Dy-b) shows Single Molecular Magnet (SMM) behavior under a 0 T magnetic field. However, R-Dy-a is a field-induced SMM.