Design and Synthesis of Porous Coordination Polymers Showing Unique Guest Adsorption Behaviors

Gas storage and separation are becoming a high priority area of research due to economic, industrial, and environmental reasons. The last two decades have therefore witnessed dramatic growth in the search for more efficient and adaptable nanoporous materials. In particular, much attention has been focused on porous coordination polymers (PCPs) or metal organic frameworks (MOFs) as new nanoporous materials. Based on the unlimited combination of metal ions and organic ligands, PCPs can provide infinite variety of nanospace in their pores. As molecular adsorption is dependent on the size, shape, and surface nature of nanospace, many unique molecular adsorption or trapping phenomena have been reported in this class of compounds. In this account, I focus on how thoughtful design can lead to the synthesis of porous coordination polymers that demonstrate unprecedented adsorption behavior not found in other porous materials. Examples include selective adsorption of acetylene over carbon dioxide in the CPL series of PCPs, using charge-transfer to induce selective adsorption of nitric oxide and oxygen in TCNQ (7,7,8,8-tetracyano-p-quinodimethane) based PCP and light-induced on-demand adsorption and structural transformations in CID-based PCPs. The guidelines underpinning such unique, highly selective guest adsorption are discussed.