Polar Lanthanide Anthracene Complexes Exhibiting Magnetic, Luminescent and Dielectric Properties

Multifunctional molecular materials combining magnetic, luminescent and dielectric properties are attractive for potential applications in spintronics and molecular devices. Herein we report three isostructural mononuclear lanthanide phosphonates, namely, Ln(NO3)(3)(2-deap)(3) [Ln=Dy (1Dy), Er (2Er), Yb (3Yb), 2-deap=diethyl anthrancen-2-ylphosphonate] which crystallize in polar space group Pna2(1). Magnetic studies revealed field-induced slow magnetization relaxation for 1Dy and 3Yb, but not for 2Er down to 1.8 K. Theoretical calculations were conducted to rationalize the magneto-structural relationship. The photoluminescent properties are also dependent on the lanthanide ion. For 1Dy, luminescence was observed only in the visible region mainly originating from the ligand. For 2Er, luminescence was observed only in the near-infrared (NIR) region due to a complete energy transfer from the ligand to the Er-III ion. Regarding to 3Yb, luminescence was observed in both visible and NIR regions suggesting a partial energy transfer from the ligand to Yb-III ion. Dielectric and piezoelectric measurements were performed on single crystals of 3Yb, which confirmed the presence of high dielectric anisotropy and weak piezoelectric response.