An Ultrastable Europium(III)–Organic Framework with the Capacity of Discriminating Fe²⁺/Fe³⁺ Ions in Various Solutions

An ultrastable luminescent europium–organic framework, {[Eu­(L)­(H2O)2]·NMP·H2O}n (CTGU-2; NMP = N-methyl-2-pyrrolidone), can first detect Fe2+/Fe3+ cations in different medium systems with high selectivity and sensitivity, and it also exhibits high sensitivity for Cr2O72– anion and acetone with a wide linear range and a low detection limit.