A pair of mononuclear Dy(iii) enantiomers showing single-ion magnetic and ferroelectric properties

Abstract

Using enantiopure ligands (–)/(+)-4,5-pinene-2,2′-bipyridine (L_R/L_S) to react with Dy(btfa)₃·2H₂O, respectively, a pair of Dy(III) enantiomers with the formulae Dy(btfa)₃L_R (R-1) and Dy(btfa)₃L_S (S-1, btfa⁻ = 3-benzoly-1,1,1-trifluoroacetonate) were obtained and structurally characterized. Each Dy(III) ion in R-1 and S-1 is octa-coordinate and adopts approximately a square-antiprismatic (SAP) geometry with D_4d symmetry. Studies on the magnetic and ferroelectric properties of R-1 were carried out and the investigation results of the magnetic properties revealed that it displays a slow magnetic relaxation behavior under a zero direct-current (dc) field, confirming its single-ion magnetic (SIM) characteristic with an effective energy barrier of 95.4(1.5) K. Moreover, R-1 crystallizes in the ferroelectric point group C₁, and exhibits ferroelectricity with a notable remnant polarization (P_r) value of 3.75 μC cm⁻² at room temperature. All these research results also suggested that R-1 and S-1 are potential multifunctional molecule-based materials combining chiroptical activities, and ferroelectric and SIM properties within one molecule.