Synthesis, crystal structures, and luminescent properties of two types of lanthanide phosphonates

Abstract

Hydrothermal reactions of different lanthanide(III) salts with an amino-diphosphonate ligand (H 4L=C 6H 5CH 2N(CH 2PO 3H 2) 2) led to two series of lanthanide phosphonates, namely, Ln(H 2L)(H 3L) ( Ln=La, 1; Pr, 2; Nd, 3; Sm, 4; Eu, 5; Gd, 6; Tb, 7). Compounds 1–5 feature a one-dimensional (1D) chain structure in which dimers of two edge-sharing LnO 8 polyhedra are interconnected by bridging phosphonate groups, such 1D arrays are further interlinked via strong hydrogen bonds between non-coordinated phosphonate oxygen atoms into a two-dimensional (2D) layer with the phenyl groups of the ligands orientated toward the interlayer space. Compounds 6 and 7 also show a different 1D array in which the LnO 6 octahedra are bridged by phosphonate groups via corner-sharing, such chains are also further interlinked by hydrogen bonds into a 2D supramolecular layer. Compounds 5 and 7 emit red and green light with a lifetime of 2.1 and 3.7 ms, respectively.