A series of Ln₄^III clusters: Dy₄ single molecule magnet and Tb₄ multi-responsive luminescent sensor for Fe³⁺, CrO₄²⁻/Cr₂O₇²⁻ and 4-nitroaniline

Abstract

Five tetranuclear lanthanide clusters of compositions [Ln₄L₄(NO₃)₂(Piv)₂]·2CH₃OH (Ln = Gd (1), Tb (2), Dy (3), Ho (4), Er (5); H₂L = 2-(((2-hydroxy-3-methoxybenzyl)imino)methyl)-6-methoxyphenol; Piv = pivalic acid) were synthesized under solvothermal conditions. The structures of 1-5 were characterized by single-crystal X-ray crystallography. Complexes 1-5 possess a zig-zag topology with [Ln₄O₆] cores being formed by the fusion of oxygen atom-bridged two [Ln₂O₂] moieties. Direct-current magnetic susceptibility studied in the 2-300 K range revealed weak antiferromagnetic interactions in 1, 2, 4, 5 and ferromagnetic interactions in 3. Complex 3 exhibits single molecule magnet (SMM) behavior. The luminescence studies indicated that complex 2 can serve as highly sensitive and selective luminescent materials for Fe³⁺, CrO₄ ^2-, Cr₂O₇ ^2- and 4-nitroaniline (4-NA), demonstrating that complex 2 should be a potential candidate for multi-responsive luminescent sensor.