Flexible MOF-aminoclay nanocomposites showing tunable stepwise/gated sorption for C2H2, CO2 and separation for CO2/N2 and CO2/CH4

Miniaturization of flexible metal-organic frameworks (F-MOFs) to nanoscale is expected to show interesting structural dynamics and serve numerous applications from separation and drug delivery to sensing. However, nanoscale F-MOFs or their composites have remained largely unexplored to date. Here, we present a new and facile method to stabilize F-MOF nanocrystals on an aminoclay (AC) template and study their tunable, enhanced gas adsorption and separation properties. We demonstrate miniaturization of two different 2D F-MOFs, {[Cu(pyrdc)(bpp)](5H(2)O)}(n) (F-MOF1) with a pillared-bilayer structure and {[Cu(dhbc)(2)(4,4'-bpy)]center dot H2O} (F-MOF2) with an interdigitated network, on AC that acts as a functional template to grow and stabilize MOF nanocrystals. Different F-MOF1@AC composites were synthesized where the gate/step pressure for specific adsorbate molecules (CO2/C2H2) could be tuned by varying the AC content. Enhanced guest adsorption with stepwise behaviour has also been realized in a certain composite. Breakthrough column experiments with the F-MOF2@AC composite show its capability to separate CO2/N-2 and CO2/CH4 gas mixtures under ambient conditions.