Complex natural systems usually have a hierarchical organization of multiple components at various scales. The well-defined hierarchical modules and their sequences in natural systems, such as brain networks, enable complicated functions and behaviors. These features have inspired me to engineer heterarchy and hierarchy in metal-organic frameworks (MOFs) for complicated applications involving cooperative behaviors. Chapter I of this dissertation discusses the general concepts and motivations to design tailored MOF architectures with controllable hierarchy and heterogeneity. MOFs are a well-developed class of porous crystalline materials that are constructed from metal-ligand coordination bonds. The modular features of building blocks enable us to organize these units into well-organized porous framework materials. Strategies to engineer heterarchy and hierarchy of MOFs are firstly introduced from a molecular level in Chapter II to IV. Chapter II of the dissertation describes the methods to introduce compositional heterogeneity into multicomponent MOFs through imprinted synthesis. In this chapter, controllable apportionment of functional groups inside MOFs can be obtained by utilizing flexible linker templates with tunable lengths. Chapter III of this dissertation further explores the effects of functional group apportionment on the formation of hierarchical pores inside MOFs via post-synthetic selective linker thermolysis. It was found that mixed-linker MOFs with a domain-based apportionment could be transformed into hierarchically porous MOFs upon selective thermolysis. To study dynamic behaviors inside hierarchically porous MOFs, Chapter IV discusses strategies such as linker reinstallation to induce lattice expansion and contraction of a whole framework. This is followed by Chapter V and VI, where chemistry at a mesoscopic level is explored in a series of multicomponent and hierarchical composites. Chapter V of the dissertation introduces the concept of retrosynthesis into the preparation of MOF-on-MOF structures with internal sequences. Chapter VI of the dissertation further extends the scope of modular synthesis, and emphasizes the power of modular programming in preparing MOF@polymer composites. In the last Chapter VII, a summary of current work and a trend description of future direction are provided, while my humble thoughts and outlooks on future smart MOF system are also presented.
