This review summarizes recent developments of coordination cages catalysis across three key approaches: (1) cavity promoted reactions, (2) embedding of active sites in the structure of the cage, and (3) encapsulation of catalysts within the cage.

A luminescent europium–organic framework with tubular channels based on the H₄BTMIPA ligand (H₄BTMIPA = 5,5′-methylenebis(2,4,6-trimethylisophthalic acid)) was assembled and characterized. The [H₂N(CH₃)₂]⁺ ions as counterions are located in the channels. The cation exchange between [H₂N(CH₃)₂]⁺ and metal ions resulted in complex 1 that can selectively sense Fe³⁺ and Al³⁺ ions through fluorescence quenching and enhancement, respectively.

Metal–organic frameworks (MOFs) based on Ti-oxo clusters (Ti-MOFs) represent a naturally self-assembled superlattice of TiO₂ nanoparticles separated by designable organic linkers as antenna chromophores, epitomizing a promising platform for solar energy conversion. However, despite the vast, diverse, and well-developed Ti-cluster chemistry, only a scarce number of Ti-MOFs have been documented. The synthetic conditions of most Ti-based clusters are incompatible with those required for MOF crystallization, which has severely limited the development of Ti-MOFs. This challenge has been met herein by the discovery of the [Ti₈Zr₂O₁₂(COO)₁₆] cluster as a nearly ideal building unit for photoactive MOFs. A family of isoreticular photoactive MOFs were assembled, and their orbital alignments were fine-tuned by rational functionalization of organic linkers under computational guidance. These MOFs demonstrate high porosity, excellent chemical stability, tunable photoresponse, and good activity toward photocatalytic hydrogen evolution reactions. The discovery of the [Ti₈Zr₂O₁₂(COO)₁₆] cluster and the facile construction of photoactive MOFs from this cluster shall pave the way for the development of future Ti-MOF-based photocatalysts.

During the various applications of MOFs, the photoluminescence properties of MOFs have received growing attention, especially for nitroaromatics (NACs) sensing. In this highlight, we summarize the progress in recent research in NACs sensing based on MOFs and sensing applications for nano-MOF type materials and MOF film.