Anti-DUT monoclonal antibody, clone 2D0

Water stability in acidic, neutral, and basic aqueous solutions is quite important for the potential application of metal organic frameworks. As evidenced by X-ray diffraction and scanning electron microscopy results, the pristine DUT-4 is extremely water sensitive to acidic, neutral, and basic aqueous solutions and undergoes crystal structure and morphology transformation. The pristine DUT-4 nearly loses its porosity and H-2 uptake capacity after being exposed for 6 d. A facile solution-immersion approach was employed to deposit a hydrophobic layer on the DUT-4 surface without significant loss of surface area. This layer could effectively protect DUT-4 from water molecule attack and greatly enhance water stability. After the same exposure to aqueous solutions, the hydrophobic-treated DUT-4 could basically retain their crystal structure, morphology, surface area, and H2 uptake capacity. This approach could be explored to broaden the scope of practical applications of DUT-4 and other metal organic frameworks under water-containing environments.

Temperature-responsive flexibility in metal-organic frameworks (MOFs) appeals to the imagination. The ability to transform upon thermal stimuli while retaining a given crystalline topology is desired for specialized sensors and actuators. However, rational design of such shape-memory nanopores is hampered by a lack of knowledge on the nanoscopic interactions governing the observed behavior. Using the prototypical MIL-53(Al) as a starting point, we show that the phase transformation between a narrow-pore and large-pore phase is determined by a delicate balance between dispersion stabilization at low temperatures and entropic effects at higher ones. We present an accurate theoretical framework that allows designing breathing thermo-responsive MOFs, based on many-electron data for the dispersion interactions and density-functional theory entropy contributions. Within an isoreticular series of materials, MIL-53(Al), MIL-53(Al)-FA, DUT-4, DUT-5 and MIL-53(Ga), only MIL-53(Al) and MIL-53(Ga) are proven to switch phases within a realistic temperature range.