Controlling phase in low-nuclearity calixarene-capped porous coordination cages with ligand functionalization

Abstract

Porosity in low-nuclearity coordination cages is relatively rare as cages with larger pore sizes are usually targeted as a way to increase gas adsorption capabilities in this promising class of molecular adsorbents. This work presents the design, synthesis, and characterization of a series of carbazole dicarboxylic acid bridged calixarene capped cages that exhibit significant porosity to N₂ and CO₂ given their limited size, presenting with Braun–Emmett–Teller (BET) surface areas in excess of 450 m² g⁻¹ and 350 m² g⁻¹, respectively. Furthermore, we report, to the best of our knowledge, the first class of calixarene capped cages bridged by a ligand with a 90° bridging angle in addition to the first permanently porous calixarene cage to utilize Mn²⁺ cations.