Lanthanide oxalatophosphonates with two- and three-dimensional structures

Reactions of lanthanide nitrate, oxalate sodium and 2-pyridylmethylphosphonic acid (2-pmpH2) under hydrothermal conditions result in five new lanthanide oxalatophosphonates with two types of structures. Compounds [Ln4(ox)5(2-pmpH)2(H2O)7].5H2O [Ln3+=Gd (1), Tb (2), Dy (3); ox2-=C2O42-] exhibit a double layer structure, made up of net-like {Ln4(ox)5}n layers containing Ln10(ox)10 rings which are connected by 2-pmpH-. While compounds [Ln4(ox)5(2-pmpH)2(H2O)6].6H2O [Ln3+=Ho (4), Yb (5)] display a three-dimensional framework structure in which the {Ln4(ox)5}n layers are cross-linked by 2-pmpH. The solid state luminescent and magnetic properties are investigated. - Graphical abstract: Compounds [Ln4(ox)5(2-pmpH)2(H2O)7].5H2O (Ln=Gd, Tb, Dy; 2-pmp=2-pyridylmethylphosphonate) and [Ln4(ox)5(2-pmpH)2(H2O)6].6H2O (Ln=Ho, Yb) with 2D and 3D structures, respectively, are reported.