Two series of pH-dependent lanthanide complexes showing solvent-induced single crystal to single crystal transformation, sorption and luminescence properties

Abstract

Two series of new lanthanide coordination polymers have been obtained by solvothermal reaction of Ln(NO₃)₃ and pamoic acid under different pH values. Both series of compounds show three-dimensional porous frameworks composed of dinuclear Ln(III) subunits. Series B demonstrates fascinating solvent-induced dynamic behaviors in an SCSC (single crystal to single crystal) manner. The capability of activated series B to absorb liquid acetone was investigated by means of ¹H NMR spectroscopy, demonstrating the potential of Ln-MOFs as highly efficient and reusable liquid acetone sorbents. In addition, photoluminescence properties of Nd (3), Eu (5) and Yb (10) were measured and discussed. Lanthanide contraction effect also played a crucial role in the formation of each series of complexes. Analysis of the relations between the ionic radius (Ln³⁺) and the number of f electrons in these complexes indicates that lanthanide contraction effect in both series can be well described by the Raymond model.