Modulator approach for the design and synthesis of anisotropic multi-domain metal–organic frameworks

Multi-domain metal-organic frameworks (MD-MOFs) consist of chemically-distinct interconnected MOF domains. Most commonly they are isotropic, with core-shell and stratified MOFs representing classic examples in which a core MOF is concentrically encased in one or more MOF shells. Anisotropic multi-domain MOFs (AMD-MOFs) are much rarer and are projected to exhibit unique properties that depend on domain sequence, composition, and 3-D spacial distribution. However, straightforward approaches for their synthesis and construction are underdeveloped. We present and describe a modulator-based strategy for preparing a diverse collection of AMD-MOFs. Designed coordination modulators were used to inhibit secondary domain growth along certain facets of seed MOF crystals. Through multistep syntheses, this strategy allows for controlled construction of AMD-MOFs with different domain distributions that depend on modulator identity and domain synthesis sequence. The reported results represent important steps toward realizing a more general synthetic approach for fabricating arbitrarily complex AMD-MOFs, which is crucial for enabling broader exploration and study of their properties, functions, and applications.