Chiral and kryptoracemic Dy(iii) complexes with field-induced single molecule magnet behavior

Abstract

Two mononuclear Dy(III) compounds formulated as [Dy(PNO)₆(H₂O)₂]Br₃ (1) and [Dy(PNO)₆(NO₃)](ClO₄)₂ (2) have been synthesized and characterized. Single crystal X-ray diffraction studies show that chiral and kryptoracemic structures are formed when different anions are introduced into the system. 1 crystallizes in the non-polar orthorhombic space group P2₁2₁2₁, whereas 2 assembles as a kryptoracemate in the polar monoclinic space group P2₁. The optical activity of the single crystals of these two compounds was confirmed by circular dichroism (CD) studies. Thermal gravimetric analyses (TGA) revealed that they are stable up to 376 K (1) and 428 K (2). Differential scanning calorimetry (DSC) measurements demonstrate the absence of structural phase transitions over the investigated temperature range. Magnetic studies show that both compounds are field-induced single molecule magnets (SMMs) with energy barriers of 36 (±0.8) K for 1 and 32 (±1.4) K for 2. Furthermore, the dielectric and ferroelectric properties of compound 2 were also investigated.