We seek to develop new MOFs for sensing and removal of toxic gases (e.g., SO2) and request 4 days on POLARIS to study the structural binding details and dielectric data simultaneously as SO2 is adsorbed in two stable MOFs (MFM-170·H2O and MFM-174). We will use our microwave frequency resonator sample environment and gas delivery system, which has been used successfully at POLARIS. This proposal aims to perform correlation studies that will enable the determination of the structural origins of changes in dielectric behaviour as SO2 molecules are bound within the MOF structure, insights into the mechanism of sequestration as well as offering a new opportunity for the development of ex-situ portable molecular sensors for toxic gases.