2D Windmill-like Ln-Containing Organophosphonate-Based Polyoxomolybdates: Synthesis, Characterization, Fluorescence, and Magnetism

By integration of {Ln(H2O)6}3+ into organophosphonate-based polyoxometalates, three Ln-containing organophosphonate-functionalized polyoxomolybdates Na1.5H1.5[{Ln(H2O)6}2{(Mo3O8)(O3PC(C3H6NH3)OPO3)}4]·(CH3CO2)·43H2O (Ln = Eu (1), Tb (2), and Dy (3)) are successfully prepared and systematically characterized. The X-ray crystallography analyses display complexes 1–3 crystallize in the C2/c space group of the monoclinic system and compose several distinctive tetramer windmill-like compounds that further assemble into two-dimensional (2D) frameworks associated with the {Ln(H2O)6}3+ core. The fluorescence spectra of 1–3 show red, green, and chartreuse emissions, respectively, originating in the typical f–f transitions of Ln3+ ions. More interestingly, complex 3 shows the field-induced single-molecule magnet (SMM) properties, resulting from the fact that [(Mo3O8)4{O3PC(C3H6NH3)OPO3}4]8– offers excellent magnetic isolation for Dy3+ ions by the nearest Dy1···Dy2 distance of 11.207 Å. The study demonstrates that the incorporation of {Ln(H2O)6}3+ into organophosphonate-based polyoxomolybdates is an effective synthetic strategy in implementing late-model opto-magnetic materials.