A series of Ln4III clusters: Dy4 single molecule magnet and Tb4 multi-responsive luminescent sensor for Fe3+, CrO42−/Cr2O72− and 4-nitroaniline

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+, CrO42−, Cr2O72− and 4-nitroaniline (4-NA), demonstrating that complex 2 should be a potential candidate for multi-responsive luminescent sensor.