Fabrication of a Luminescence-Silent System Based on a Post-Synthetic Modification Cd-MOFs: A Highly Selective and Sensitive Turn-on Luminescent Probe for Ascorbic Acid Detection

A unique three-dimensional luminescent metal–organic framework (Cd-MOFs), [Cd(tpbpc)2]·2H2O·DMF (Htpbpc = 4′-[4,2′;6′,4″]-terpyridin-4′-yl-biphenyl-4-carboxylic acid; DMF = dimethylformamide), was synthesized and structurally characterized; it exhibits excellent luminescent property and structural stability in aqueous solutions. Interestingly, an unparalleled luminescence-silent system CrO42–@Cd-MOFs was successfully fabricated by postsynthetic modification of metal–organic frameworks. This luminescence-silent system represents a highly selective and sensitive turn-on luminescent responding to ascorbic acid. First, this advanced fluorescent sensor displays excellent performance for CrO42– ions with a quenching of fluorescence intensity originating from fluorescence resonance energy transfer (FRET) mechanism. What’s more, the fluorescent intensity of CrO42–@Cd-MOFs system can be recovered (turn-on) for sensing ascorbic acid because of the elimination of FRET process. Such a novel fabrication strategy should offer the guidance to develop various MOFs-implicated luminescence-silent systems as “turn-on” sensors for detection of specific chemicals.