“Node Chemistry in Metal-Organic Framework Materials”

Metal-organic frameworks (MOFs) are an intriguing class of nanoporous crystalline solids that can be readily self-assembled by combining metal ions (or clusters) and multitopic organic ligands via coordination bondings. Often characterized by extended nano-porosity and large internal surface area, MOFs are being examined as candidates for applications in chemical separations, gas storage, ionic conduction, and chemical sensing. In particular, the open coordination site (OCS) on intersectional metal ion has shown considerable potential in its role for the applications in i.e., high ion transport and efficient gas adsorption. Thus, the activation of MOFs, the removal of solvent molecules (typically used in during the synthesis) from the OCSs has been thought as a prerequisite process for those applications. To date, several strategies for activating MOFs have been suggested–freezing-drying; supercritical CO2 exchange; solvent-exchange; thermal treatment–, but the thermal activation has been a unique way to remove the OCS-coordinated solvent molecule. Given that the high temperature (e.g.,>150°C) can lead to structural damage to MOFs, conceivable low-temperature process will be a considerably promising way, compared to the cumbersome, pricey heat-and-vacuum technique.

In this presentation, I will discuss about how to utilize metal node in metal-organic framework materials. As a representative example, I will show a new activation method, “chemical activation”, where methylene chloride (MC) plays a substantial role in removing both metal-coordinating and pore-filling solvents even at room-temperature. While MC treatment is surely a well-known method for replacing pore-filling solvent, the role of MC for breaking the metal-solvent coordination has never been demonstrated. We find that the chemical activation by MC arises via intermediation of spontaneous MC-metal weak coordination. Further, I will show an easy method to fabricate large-area MOF films and a strategy that can give chemical functions to metal node in a MOF.

20160331_세미나_Prof. Nak Cheon Jeong.hwp