Fast, Sensitive, and Selective Ion-Triggered Disassembly and Release Based on Tris(bipyridine)ruthenium(II)-Functionalized Metal-Organic Frameworks

Metalorganic frameworks (MOFs) are microporous materials assembled from metal ions and organic linkers. Recently, many studies have been focused on the syntheses of MOFs with permanent porosity for various applications. However, no attention has been paid to controllable disassembly of MOFs and related applications. In this work, for the first time we synthesized novel tris(bipyridine)ruthenium(II)-functionalized MOFs (i.e., RuMOFs) that could be ion-responsively disassembled and release massive guest materials loaded in the frameworks. The synthesized RuMOFs exhibited much stability in aqueous solutions containing H+, and many metal ions, but could be selectively and sensitively disassembled by Hg2+ ions, resulting in the release of large quantities of Ru(bpy)(3)(2+). The target-responsive release mechanism was investigated and discussed in detail. On the basis of the ion-responsive disassembly and release, an ultrasensitive electrochemiluminescence sensing method for Hg2+ has been developed with a very low limit of detection (5.3 X 10(-13) M). It was envisioned that the RuMOFs and similar target-responsive functional MOF materials would have promising applications in ultrasensitive and highly selective chemical sensing and even in accurately controllable drug delivering and releasing.