Vapor-Phase Metallation by Atomic Layer Deposition In a Metal−Organic Framework

ABSTRACT: Metal−organic frameworks (MOFs) have received attention for a myriad of potential applications including catalysis, gas storage, and gas separation. Coordinatively unsaturated metal ions often enable key functional behavior of these materials. Most commonly, MOFs have been metalated from the condensed phase (i.e., from solution). Here we introduce a new synthetic strategy capable of metallating MOFs from the gas phase: atomic layer deposition (ALD). Key to enabling metal-ation by ALD In MOFs (AIM) was the synthesis of NU-1000, a new, thermally stable, Zr-based MOF with spatially oriented −OH groups and large 1D mesopores and apertures. Metal−organic frameworks (MOFs) are a class of hybridmaterials comprising inorganic nodes and organic linkers.1−3 In many instances coordinatively unsaturated metal sites (either at the linkers or the nodes) are essential for generating desired functional behavior such as catalysis,4 gas storage,5 and gas separation.6 Most often MOFs have been metal-functionalized from the condensed phase (i.e., solution) either in de novo fashion or via postsynthesis modification.7 Unfortunately, considerable effort is necessary to ensure that excess metals or undesired solvent and other reagents are removed from solution-metalated MOFs. Solvent molecules can also irreversibly ligate otherwise coordinatively unsaturated metal sites, thus yielding less than desirable materials properties.8 Hence, new synthetic strategies capable of uniformly incorporating open metal sites within MOFs may be attractive for obtaining new functional materials. Postsynthesis metalation from the vapor-phase could eliminate purification and activation steps and circumvent problems associated with site blocking by solvent molecules. Meilikhov et al. synthesized a variety of metal inclusion compounds (i.e.