Atomic Layer Deposition in a Metal-Organic Framework: Synthesis, Characterization, and Performance of a Solid Acid

Rimoldi, M.; Bernales, V.; Borycz, J.; Vjunov, A.; Gallington, L. C.; Platero-Prats, A. E.; Kim, I. S.; Fulton, J. L.; Martinson, A. B. F.; Lercher, J. A.; Chapman, K. W.; Cramer, C. J.; Gagliardi, L.; Hupp, J. T.; Farha, O. K.
Chem. Mater. 2017, 29, 1058 (doi:10.1021/acs.chemmater.6b03880).

NU-1000, a zirconium-based metal-organic framework featuring mesoporous channels, has been post-synthetically metalated via atomic layer deposition in MOF (AIM) employing dimethylaluminum iso-propoxide ([Al-Me₂ⁱOPr]₂ – DMAI), a milder precursor than widely used trimethylaluminum (AlMe₃ – TMA). The aluminum-modified NU-1000 (Al-NU-1000) has been characterized with a comprehensive suite of techniques that points to the formation of aluminum oxide clusters well dispersed through the framework and stabilized by confinement within small pores intrinsic to the NU-1000 structure. Experimental evidence allows for identification of spectroscopic similarities between Al-NU-1000 and γ-Al₂O₃. Density functional theory modeling provides structures and simulated spectra the relevance of which can be assessed via comparison to experimental IR and EXAFS data. The catalytic performance of Al-NU-1000 has been benchmarked against γ-Al₂O₃, with promising results in terms of selectivity.