Near-infrared luminescence and SMM behaviors of a family of dinuclear lanthanide 8-quinolinolate complexes

Abstract

A new family of lanthanide complexes, [Ln₂(dbm)₄(OQ)₂(CH₃OH)₂] (Ln = Nd (1), Tb (2), Dy (3), Ho (4); dbm = dibenzoylmethanate, OQ = 8-quinolinolate), and [Er₂(dbm)₄(OQ)₂(CH₃OH)]·CH₃COCH₃ (5) were synthesized and characterized using single-crystal X-ray diffraction, elemental analysis (EA), thermal gravimetric analysis (TGA), powder X-ray diffraction (PXRD) and UV-vis spectra. X-ray crystallographic analyses reveal that 1–5 are μ-phenol bridged dinuclear complexes. For complexes 1–4, each Ln^III ion is eight-coordinated with two bidentate dbm and two μ-phenol bridging OQ ligands and one methanol molecule. Complex 1 in the solid-state displays the typical emissions of the Nd^III ions in the NIR region. Magnetic measurements were carried out on complexes 1–5. Dynamic magnetic studies reveal single-molecule magnet (SMM) behavior for complex 3. Fitting the dynamic magnetic data to the Arrhenius law gives the energy barrier ΔE/k_B = 109.5 K and pre-exponential factor τ₀ = 4.23 × 10⁻⁹ s under 3000 Oe dc field.