Synthesis and characterization of low-nuclearity lantern-type porous coordination cages

Abstract

Permanent porosity in lantern-type M₄L₄ paddlewheel-based cages is rare and has only been reported for naphthalene, naphthyridine, and diethynylbenzene-based linkers. This work presents the design, synthesis, and characterization of small lanterns that exhibit CO₂ accessible BET surface areas in excess of 200 m² g⁻¹. The crystal packing and porosity of these cages can be tuned by either ligand functionalization or the choice of M²⁺ source used in their synthesis. Given their low nuclearity, these cages with internal M–M distances of less than 5 Å represent the lower size limit for permanently microporous coordination cages.