A series of Ln 4 III clusters: Dy 4 single molecule magnet and Tb 4 multi-responsive luminescent sensor for Fe 3+ , CrO 4 2- /Cr 2 O 7 2- and 4-nitroaniline.

Five tetranuclear lanthanide clusters of compositions [Ln 4 L 4 (NO 3 ) 2 (Piv) 2 ]·2CH 3 OH (Ln = Gd (1), Tb (2), Dy (3), Ho (4), Er (5); H 2 L = 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 [Ln 4 O 6 ] cores being formed by the fusion of oxygen atom-bridged two [Ln 2 O 2 ] 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 Fe 3+ , CrO 4 2- , Cr 2 O 7 2- and 4-nitroaniline (4-NA), demonstrating that complex 2 should be a potential candidate for multi-responsive luminescent sensor.