3-Pyridylacetic-Based Lanthanide Complexes Exhibiting Magnetic Entropy Changes, Single-Molecule Magnet, and Fluorescence

[Image: see text] Four complexes from lanthanides, 3-pyridylacetate, and 1,10-phenanthroline, formulated as [Ln(2)(3-PAA)(2)(μ-Cl)(2)(phen)(4)](ClO(4))(2) [Ln = Gd(1), Dy(2), Eu(3), Tb(4), 3-PAA = 3-pyridylacetic acid, phen = 1,10-phenanthroline], were obtained. The four compounds were characterized by IR spectra, thermogravimetric analyses, powder X-ray diffraction, and single-crystal X-ray diffraction. Compounds 1–4 are isomorphous, and they have a dinuclear structure. Magnetic studies reveal that 1 shows the magnetocaloric effect with −ΔS(m)(max) = 19.03 J kg(–1) K(–1) at 2 K for ΔH = 5 T, and 2 displays a field-induced single-molecule magnet with U(eff) = 19.02 K. The photoluminescent spectra of 3 and 4 exhibit strong characteristic emission, which demonstrate that the ligand-to-Eu(III)/Tb(III) energy transfer is efficient.