Synthesis and Structure of an Aqueous Stable Europium-Based Metal-Organic Framework with Ratiometric Fluorescence Sensing for Phosphate and Luminescence Quenching for Salicylaldehyde.

An aqueous stable europium-based metal-organic framework with properties of ratiometric fluorescence sensing, namely, {[(CH)NH][Eu(TCPB)(HO)]·DMF} (; HTCPB = 1,2,4,5-tetrakis(4-carboxyphenyl)-benzene), was synthesized under solvothermal conditions and structurally characterized. Crystal structure analysis shows that is a three-dimensional porous crystal, in which the Eu ion is an eight-coordinate square inverse prism with eight oxygen atoms. Fluorescence measurements show that exhibits characteristic emission of the Eu ion and ligand. displays good selectivity and sensitivity as a ratiometric fluorescence sensor for phosphate anions with a low detection limit in Tris-HCl buffer solution. Furthermore, also has a good ability to identify salicylaldehyde through fluorescence quenching with a detection limit of 0.095 ppm. Therefore, it is an excellent fluorescent sensing material for phosphate and organic salicylaldehyde.