Many sophisticated chemical and physical properties of porous materials strongly rely on the presence of the metal ions within the structures. Whereas homogeneous distribution of metals is conveniently realized in metal–organic frameworks (MOFs), the limited stability potentially restricts their practical implementation. From that perspective, the development of metal–covalent organic frameworks (MCOFs) may address these shortcomings by incorporating active metal species atop highly stable COF backbones. This Minireview highlights examples of MCOFs that tackle important issues from their design, synthesis, characterization to cutting‐edge applications.

The tunable inorganic nodes and modifiable organic linkers enable the designable functionality to come true in the new-type porous hybrid materials, namely metal-organic frameworks (MOFs). By using viologen-functionalized mbenzenedicarboxylate as organic linker, a terbium-organic framework embedded with asymmetric viologen species has been constructed. The reversible photochromism from bright yellow to dark green is implemented due to favorable spatial stack of the electron donor and acceptor. The photochromic component of the organic linkers can modulate the luminescence of tetranuclear terbium cluster under irradiation of UV light, which is defined as photoluminescence switch behavior. The different protonation levels of uncoordinated N atoms with varying pH enable the MOF as a potential fluorescent pH sensor. Thus, multi-photofunctionality, viz. photoluminescence, photochromism as well as the derivate fluorescent response to irradiation and pH have been combined in the Tb-MOF, which is the first example in the viologen-based photochromic hybrid materials.

Owing to the unique structural features and facile tunability of the subcomponents and channels, chiral COFs show great potential in heterogeneous catalysis, enantioselective separation, and recognition.

Atomically precise enantiomeric metal clusters are scarce, and copper(I) alkynyl clusters with intense circularly polarized luminescence (CPL) responses have not been reported. A pair of chiral alkynyl ligands, (R/S)‐2‐diphenyl‐2‐hydroxylmethylpyrrolidine‐1‐propyne (abbreviated as R/S‐DPM) we successfully prepared and single crystals were characterized of optically pure enantiomeric pair of atomically‐precise copper(I) clusters, [Cu14(R/S‐DPM)8](PF6)6 (denoted as R/S‐Cu14), which feature bright red luminescence and CPL with a high luminescence anisotropy factor (glum). A dilute solution containing R/S‐Cu14 was nonluminescent and CPL inactive at room temperature. Crystallization‐ and aggregation‐induced emission (CIE and AIE, respectively) contribute to the triggering of the CPL of R/S‐Cu14 in the crystalline and aggregated states. Their AIE behavior and good biocompatibility indicated applications of these copper(I) clusters in cell imaging in HeLa and NG108‐15 cells.

A new stable Zr-based MOP is successfully constructed. Unique cavity and 2D hydrogen-bonding networks endow the MOP with highly selective CO2 capture and excellent proton conduction.