The construction of three-dimensional (3D) covalent organic frameworks (COFs) remains challenging due to the limited types of organic building blocks. With octahedral Ti IV complex as the building unit, this study reports on the first 3D anionic titanium-based COF (Ti-COF-1) with an edgetransitive (6, 4)-connected soc topology. Ti-COF-1 exhibits high crystallinity, superior stability, and large specific surface area (1000.4 m 2 g À1 ). Moreover, Ti-COF-1 has a broad absorption band in the UV spectrum with an optical energy gap of 1.86 eV, and exhibits high photocatalytic activity toward Meerwein addition reactions. This research demonstrates an attractive strategy for the design of 3D functional COFs.Scheme 1. Illustration of the MOC-to-MCOF strategy for the construction of a 3D COF with soc topology.

Three metal covalent organic frameworks (MCOFs), namely RuCOF-ETTA, RuCOF-TPB and RuCOF-ETTBA, were synthesized by incorporating the photosensitive Ru II tris(2,2'-bipyridine) unit into the skeleton. Interestingly, each RuCOF contains three isostructural covalent organic frameworks that interlock together with the Ru II centers serving as point of registry. The covalently linked network coupling with uniformly distributed Ru II units allowed the RuCOFs to exhibit superior chemical stability, strong light-harvesting ability, and high photocatalytic activity toward hydrogen evolution (20 308 μmol g À 1 h À 1 ). This work illustrates the potential of developing versatile MCOFsbased photocatalysts from functionalized metal complex building unit and further enriches the MCOFs family.

A electron donor-acceptor covalent organic framework (TTF-COF1) was constructed by imine condensation of electron donor tetraformyl-tetrathiafulvalene (TTF-fo) and electron acceptor 2,6-diaminoanthraquinone (DAQ). TTF-COF1 involves in intramolecular charge transfer, offering a...

Selective encapsulation of fullerene guests and solid state spin-crossover behaviors were observed in iron(ii) tetrahedral metal–organic cages with cube-like cavities.