A novel fluorescence phenomenon caused by amine induced ion-exchange between Cd 2+ and Fe 3+ ions.

A 3D metal-organic framework {[Cd(5-Brp)(dpa)]·0.5DMF·H 2 O} n (1) was successfully synthesized and characterized, which markedly recognized iron ions under the induction of an amino group. With the concentration of Fe 3+ increasing, the emission of 1 first declined, then enhanced with a red shift and was finally quenched, which was different from the reference compound [Cd(5-Brp)(bpp)(H 2 O)] n (2). This result drew our attention to amine induced ion-exchange. This peculiar phenomenon inspired us to construct an effective ion detector.