Two AIE-Ligand-Based 2-D Luminescent Metal-Organic Frameworks as Fe Sensors.

The design and synthesis of high-performance sensors are very important but remain great challenges. In this work, a new aggregation-induced-emission (AIE) molecule 4,4'-(((9-fluoren-9-ylidene)methylene)bis(4,1-phenylene))dipyridine () was successfully synthesized and first developed as a functional ligand to construct two isomorphic metal-organic frameworks (MOFs) [M()(OBBA)] [M = Cd (), Co (); HOBBA = 4,4'-oxybisbenzoic acid]. They adopt [M(COO)] flywheel clusters, OBBA bridges, and terminal ligands as building units to form isomorphic 2-D networks with Lewis base active cites (uncoordinated pyridyl N). Both and exhibit excellent water, pH, and thermal stabilities and extremely efficient Fe sensing abilities in the water environment. The quenching constants and detection limits reach the best levels reported so far. The sensing mechanism of and toward Fe is studied in depth, and the difference in their sensing performance is also explained.