A large-pore version of Mg-CUK-1, a water-stable MOF with 1-D channels, was synthesized in basic water. Mg-CUK-1L has a BET surface area of 2,896 m2 g-1 and shows a stark… Click to show full abstract
A large-pore version of Mg-CUK-1, a water-stable MOF with 1-D channels, was synthesized in basic water. Mg-CUK-1L has a BET surface area of 2,896 m2 g-1 and shows a stark selectivity for CO2 sorption over N2, O2, H2, and CH4. It displays reversible, multi-step gated sorption of CO2 below 0.33 atm. The dehydrated single crystal structure of Mg-CUK-1L confirms retention of the open channel structure. The MOF is thermally stable up to 450 °C and can be loaded with organic molecules by direct immersion in hot melts, providing single crystals suitable for X-ray diffraction. Trans-azobenzene fills the channels in a 2×2 end-to-end fashion. Solid-state UV-Vis spectroscopy of the composite reveals that azobenzene molecules undergo fully reversible trans-cis isomerization, despite being close-packed; this surprising result is confirmed by DFT-simulated UV-vis spectra.
               
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