A packaged toolbox with stabilization and functionalization strategies for robust and multifunctional metal–organic framework (MOF) materials has been summarized and discussed.

The incorporation of large π-conjugated ligands into metal–organic frameworks (MOFs) can introduce intriguing photophysical and electrochemical properties into the framework. However, these effects are often hindered by the strong π–π interaction and the low solubility of the arylated ligands. Herein, we report the synthesis of a porous zirconium-based MOF, Zr6(μ3-O)4(μ3-OH)4(OH)6(H2O)6(HCHC) (PCN-136, HCHC = hexakis­(4-carboxyphenyl)­hexabenzocoronene), which is composed of a hexacarboxylate linker with a π-conjugated hexabenzocoronene moiety. Direct assembly of the Zr4+ metal centers and the HCHC ligands was unsuccessful due to the low solubility and the unfavorable conformation of the arylated HCHC ligand. Therefore, PCN-136 was obtained from aromatization-driven postsynthetic annulation of the hexaphenylbenzene fragment in a preformed framework (pbz-MOF-1) to avoid π–π stacking. This postsynthetic modification was done through a single-crystal-to-single-crystal transformation and was clearly observable utilizing single -crystal X-ray crystallography. The formation of large π-conjugated systems on the organic linker dramatically enhanced the photoresponsive properties of PCN-136. With isolated hexabenzocoronene moieties as photosensitizers and Zr–oxo clusters as catalytic sites, PCN-136 was employed as an inherent photocatalytic system for CO2 reduction under visible-light irradiation, which showed increased activity compared with pbz-MOF-1.

2D metal–organic frameworks (2D‐MOFs) have recently emerged as promising materials for gas separations, sensing, conduction, and catalysis. However, the stability of these 2D‐MOF catalysts and the tunability over catalytic environments are limited. Herein, it is demonstrated that 2D‐MOFs can act as stable and highly accessible catalyst supports by introducing more firmly anchored photosensitizers as bridging ligands. An ultrathin MOF nanosheet‐based material, Zr‐BTB (BTB = 1,3,5‐tris(4‐carboxyphenyl)benzene), is initially constructed by connecting Zr 6 ‐clusters with the tritopic carboxylate linker. Surface modification of the Zr‐BTB structure was realized through the attachment of porphyrin‐based carboxylate ligands on the coordinatively unsaturated Zr metal sites in the MOF through strong Zr‐carboxylate bond formation. The functionalized MOF nanosheet, namely PCN‐134‐2D, acts as an efficient photocatalyst for 1 O 2 generation and artemisinin production. Compared to the 3D analogue (PCN‐134‐3D), PCN‐134‐2D allows for fast reaction kinetics due to the enhanced accessibility of the catalytic sites within the structure and facile substrate diffusion. Additionally, PCN‐134(Ni)‐2D exhibits an exceptional yield of artemisinin, surpassing all reported homo‐ or heterogeneous photocatalysts for the artemisinin production.

Porous coordination cages (PCCs) are discrete nanoscopic structures with intrinsic cavities. The solubility and tunable host-guest interactions allow PCCs to form a homogeneous catalytic platform. Through engineering the interactions between the host PCC and the guest nanoparticles, we succeeded in encapsulating ruthenium nanoparticles in PCCs and tuning their crystalline form to a highly reactive face-centered-cubic one. The nanoparticles within the PCC showed extraordinary reactivity toward the dehydrogenation reaction. This approach sheds light on developing high-performance catalysts through interaction engineering.

Epitaxial growth of MOF-on-MOF composite is an evolving research topic in the quest for multifunctional materials. In previously reported methods, the core-shell MOFs were synthesized via a stepwise strategy that involved growing the shell-MOFs on top of the preformed core-MOFs with matched lattice parameters. However, the inconvenient stepwise synthesis and the strict lattice-matching requirement have limited the preparation of core-shell MOFs. Herein, we demonstrate that hybrid core-shell MOFs with mismatching lattices can be synthesized under the guidance of nucleation kinetic analysis. A series of MOF composites with mesoporous core and microporous shell were constructed and characterized by optical microscopy, powder X-ray diffraction, gas sorption measurement, and scanning electron microscopy. Isoreticular expansion of microporous shells and orthogonal modification of the core was realized to produce multifunctional MOF composites, which acted as size selective catalysts for olefin epoxidation with high activity and selectivity.