Introduction of Lewis Acidic and Redox-Active Sites into a Porous Framework for Ammonia Capture with Visual Color Response

Based
on the Lewis acidic site and redox ability of bipyridinium ligand,
a porous framework with an adsorption advantage for ammonia over water
and color response ability has been constructed. The compound is highly
stable and flexible to external stimuli, exhibiting reversible single-crystal-to-single-crystal
transformations, in response to temperature change and NH3 capture. More attractively, the title compound shows obvious color
change from yellow to dark blue when exposed to ammonia vapor within
just a few seconds, indicating a strong ability to function as a visual
colorimetric absorbent for ammonia.