Smart Metal–Organic Frameworks with Reversible Luminescence/Magnetic Switch Behavior for HCl Vapor Detection

Smart luminescent metal–organic frameworks (MOFs) demonstrate promising performance in the detection of toxic gases. The incorporation of twisted or rotary organic ligands with aggregation-induced emission (AIE) characteristics can provide further opportunities in designing such smart MOFs with new topologies and stimuli-responsive behaviors. Herein, novel AIE MOFs are reported with reversible luminescence or a magnetic switch for HCl vapor detection. The twisted conformation of tetrakis(4-carboxyphenyl)ethylene (TCPE) ligand leads to the unique M⁺–L–M^?–L–M]_∞ (M = metal clusters, L = ligand) configuration for ZnMOF and CoMOF. Different from conventional MOFs with M–L]_∞ topology, ZnMOF and CoMOF exhibit a blue-to-yellow greenish fluorescence transition and a ferrimagnetic-to-antiferromagnetic switch behavior, respectively, upon recognition of HCl vapor. The adsorbed HCl molecules rather than coordinated ones are determined to be the main reason, and such luminescence and magnetic switch can be induced in a reversible manner via HCl vapor adsorption/desorption processes with high reliability. This work of AIE MOFs with twisted and rotary ligands shall pave new avenue in design of smart MOFs with new topologies and stimuli-responsive behavior for real-time sensing and detection applications.