Dinuclear lanthanide–lithium complexes based on fluorinated β-diketonate with acetal group: magnetism and effect of crystal packing on mechanoluminescence

Abstract

The synthesis of novel dinuclear lanthanide complexes with formulas [(LnL₃)(LiL)(MeOH)] (1–3) and [(LnL₃)(LiL)(H₂O)] (4–6) (Ln = Eu(III), Tb(III), Dy(III)) based on functionalized lithium β-diketonate (LiL) is reported. The coordination environment of the Ln(III) ion is formed by oxygen atoms of both the 1,3-dicarbonyl moiety and the acetal group. Depending on the solvent used for the crystallization, methanol or water molecules participate in the coordination with Li(I) ions affecting the crystal structure of complexes. In contrast to [(LnL₃)(LiL)(H₂O)] 4–6, a series of complexes [(LnL₃)(LiL)(MeOH)] 1–3 showed mechanoluminescence properties, thereby demonstrating the relationship between the observed optical properties and crystal packing architecture. The magnetic measurements of [(LnL₃)(LiL)(MeOH)] 1–3 revealed SMM behavior of [(DyL₃)(LiL)(MeOH)] 3 at low temperatures (U_eff is 37.7 cm⁻¹).