Structure Dynamics of MOFs and Their Applications
Flexible metal-organic frameworks (MOFs) have great potential for various applications including chemical sensing, drug delivery, and gas storage. Flexibility originates from reversible structural rearrangement of metal ions and organic ligands in response to external stimuli (guest adsorption, pressure, and light irradiation). Transformation behaviors of the flexible MOFs have widely been explored by theoretical calculations, gas sorption isotherms, and in situ X-ray diffraction. Although in situ transmission electron microscopy (TEM) is suitable for analyzing the structural dynamics, direct observation of the transition is still lacking because flexible MOFs are sensitive to the electron beam. Low electron dose can prevent structural deformation and trigger volume expansion/contraction. By using low-dose TEM imaging technique, we investigate the reversible transformation of flexible MOF in real-time.