A dual-responsive luminescent sensor based on a water-stable Cd(ii)-MOF for the highly selective and sensitive detection of acetylacetone and Cr2O72− in aqueous solutions

Abstract

Two new water-stable cadmium(II)-metal organic frameworks (MOFs), namely [Cd₂(L1)(1,4-NDC)₂]_n (1) and [Cd(L2)(1,4-NDC)]_n (2) (L1 = 1,4-bis(benzimidazol-1-yl)-2-butylene, L2 = 1,4-bis(2-methylbenzimidazol-1-yl)-2-butylene and 1,4-H₂NDC = 1,4-naphthalenedicarboxylic acid), were synthesized and characterized. 1 exhibits an unusual 3D framework with the Schläfli symbol of {4²·5·6²·7}{4²·5²·7²}{4²·5³·6²·7³}₂, and 2 is a classical sqc6 network. 1 and 2 display excellent pH and water stability, and the integrity of the frameworks was well maintained at different pH values (pH = 3–13) and after long-term water treatment. 1 is the first dual-function luminescent sensor for sensing acetylacetone and Cr₂O₇²⁻ in aqueous solutions with high sensitivity, selectivity and excellent recyclability. This material is an excellent dual-responsive recyclable luminescent sensor.