The
application of atomic layer deposition (ALD) to metal–organic
frameworks (MOFs) offers a promising new approach to synthesize designer
functional materials with atomic precision. While ALD on flat substrates
is well established, the complexity of the pore architecture and surface
chemistry in MOFs present new challenges. Through <i>in situ</i> synchrotron X-ray powder diffraction, we visualize how the deposited
atoms are localized and redistribute within the MOF during ALD. We
demonstrate that the ALD is regioselective, with preferential deposition
of oxy-Zn(II) species within the small pores of NU-1000. Complementary
density functional calculations indicate that this startling regioselectivity
is driven by dispersion interactions associated with the preferential
adsorption sites for the organometallic precursors prior to reaction
