Isotope-selective pore opening in a flexible metal-organic framework

Abstract

Flexible metal-organic frameworks that show reversible guest-induced phase transitions between closed and open pore phases have enormous potential for highly selective, energy-efficient gas separations. Here, we present the gate-opening process of DUT-8(Ni) that selectively responds to D 2 , whereas no response is observed for H 2 and HD. In situ neutron diffraction directly reveals this pressure-dependent phase transition. Low-temperature thermal desorption spectroscopy measurements indicate an outstanding D 2 -over-H 2 selectivity of 11.6 at 23.3 K, with high D 2 uptake. First-principles calculations coupled with statistical thermodynamics predict the isotope-selective gate opening, rationalized by pronounced nuclear quantum effects. Simulations suggest DUT-8(Ni) to remain closed in the presence of HT, while it also opens for DT and T 2 , demonstrating gate opening as a highly effective approach for isotopolog separation.

Insights into Crystal Size and Synthesis Dependent Guest-Induced Flexibility of ZIF-7 Pore Structure

“…To clarify the importance of particle size distribution we separated crystals of two different sizes from ZIF-7 (14). Here, 5 mmol of Zn(NO3)2.6H2O and 20 mmol (2.36 g) of HbIm were used as before.…”

H2/D2 Separation Using UTSA-16@CAU-10-H@γ-AlOOH Composites as the Stationary Phase in Gas Chromatography via the Additive Effects of Kinetic Sieving and Chemical Affinity Quantum Sieving

“…Deuterium is a stable isotope of hydrogen, which is not only a potential source of energy for nuclear fusion reactors but also widely used in medical and scientific experiments. , However, the abundance of deuterium is only 0.015% in nature, and the physical and chemical properties and size of the hydrogen isotopes are very similar, so the separation of D 2 from hydrogen isotopes is extremely challenging. Metal–organic framework (MOF) materials are a new type of porous materials for the separation of hydrogen isotopes in recent years. − Compared with the reported materials used in gas chromatography as stationary phase materials for the separation of hydrogen isotopes, , such as Pd–Pt alloy, zeolites, − glass microspheres, activated alumina, and carbon-based materials, the tunability of the pore structure, specific surface area, and excellent thermal stability of MOFs endow them with potential significance for hydrogen isotope separation …”

Towards controlled partial desolvation of guest-responsive Metal-Organic Frameworks for precise porosity control

“…18,19 In case of "gating" MOF DUT-8(Ni), the close pore phase is thermodynamically stable, however, adsorption of guest molecules stabilizes the open pore (OP) phase energetically. 20,21 Desolvation of stimuli responsive MOFs or often denoted as "activation" is essential before the material is explored further towards its applications. [22][23][24] Majority of the functional MOF properties relies on removal of guest molecules from the pores of MOFs after the synthesis.…”