Synthesis and structural characterisation of lanthanide coordination polymers featuring 4,4′,6,6′-tetra-carboxy-2,2′-bipyridine and rare network topology†
Abstract
Reported herein is a synthetic and structural study of the coordination chemistry of 4,4′,6,6′-tetracarboxylic acid-2,2′-bipyridine (H4tcbp) with some lanthanide ions. The reaction of H4tcbp under acidic hydrothermal conditions with Ln(III) (Ln = La, Eu and Gd) in 1 : 1 stoichiometric ratio led to the formation of crystalline {[La(Htcbp)(H2O)3]·H2O}, 1, {[La(Htcbp)(H2O)]}, 2, {[Eu(Htcbp)(H2O)]·2 H2O}, 3 and {[Gd(Htcbp)(H2O)]·2 H2O}, 4; which were structurally characterised. Using a 1 : 1 H2O/DMF-solution in combination with Eu(III) and H4tcbp gave {[Eu(tcbp)(H2O)]·(Me2NH2)}, 5, which was also structurally characterised. The acidic conditions in 1–4 yielded 1 : 1 neutral {Ln : Htcbp} complexes whereas in 5 the H4tcbp