Rapid post-synthetic modification of porous coordination cages with copper-catalyzed click chemistry

Novel cobalt calixarene-capped and zirconium-based porous coordination cages were prepared with alkyne and azide functionality to leverage post-synthetic modification by click chemistry. While the calixarene-capped cages showed impressive stability when exposed to the most straightforward copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) reaction conditions with copper(II) sulfate and sodium ascorbate as the reducing agent, milder reaction conditions were necessary to perform analogous CuAAC reactions on zirconium-based cages. Reaction kinetics were monitored by IR spectroscopy, confirming rapid reaction times (<3 hours).