Novel three-dimensional Ln–Ag 4d–4f heteropentametallic helix-based microporous metal–organic framework with unprecedented (3,4,5,6)-connected topology constructed from isonicotinate ligand

An unprecedented 4d–4f heterometallic helix-based MMOF with a new (3,4,5,6)-connected topology, {[Ln2Ag3(ina)6(ox)0.5(μ2-OH2)(H2O)2.5]·1.5H2O·2NO3}n, is presented, which consists of coaxial bi-strand helices interconnected by the carboxyl groups of the ligands. Selective anion-exchange functions of the title compound containing NO3− counter anions were identified.