ZIF-8 is a flexible zeolitic imidazole-based metal−organic framework whose
narrow pore apertures swing open by reorientation of imidazolate linkers and expand when
probed with guest molecules. This work reports on the crystal size dependency of both
structural transitions induced by N2 and Ar adsorption and dynamic adsorption behavior of
n-butanol using well-engineered ZIF-8 crystals with identical surface area and micropore
volume. It is found that the crystal downsizing of ZIF-8 regulates the structural flexibility in
equilibrium adsorption and desorption of N2 and Ar. Adsorption kinetics of n-butanol in
ZIF-8 are strongly affected by the crystal size, however, not according to a classical
intracrystalline diffusion mechanism. Our results suggest that structural transitions and
transport properties are dominated by crystal surface effects. Crystal downsizing increases
the importance of such surface barriers
