Connecting molecular building blocks by covalent bonds to form extended crystalline structures has caused a sharp upsurge in the field of porous materials, especially covalent organic frameworks (COFs), thereby translating the accuracy, precision, and versatility of covalent chemistry from discrete molecules to two-dimensional and three-dimensional crystalline structures. COFs are crystalline porous frameworks prepared by a bottom-up approach from predesigned symmetric units with well-defined structural properties such as a high surface area, distinct pores, cavities, channels, thermal and chemical stability, structural flexibility and functional design. Due to the tedious and sometimes impossible introduction of certain functionalities into COFs via de novo synthesis, pore surface engineering through judicious functionalization with a range of substituents under ambient or harsh conditions using the principle of coordination chemistry, chemical conversion, and building block exchange is of profound importance. In this review, we aim to summarize dynamic covalent chemistry and framework linkage in the context of design features, different methods and perspectives of pore surface engineering along with their versatile roles in a plethora of applications such as biomedical, gas storage and separation, catalysis, sensing, energy storage and environmental remediation.

Connecting organic building blocks by covalent bonds to design porous crystalline networks has led to covalent organic frameworks (COFs), consequently transferring the flexibility of dynamic linkages from discrete architectures to extended structures. By virtue of the library of organic building blocks and the diversity of dynamic linkages and topologies, COFs have emerged as a novel field of organic materials that propose a platform for tailor-made complex structural design. Progress over the past two decades in the design, synthesis, and functional exploration of COFs in diverse applications successively established these frameworks in materials chemistry. The large-scale synthesis of COFs with uniform structures and properties is of profound importance for commercialization and industrial applications; however, this is in its infancy at present. An innovative designing and synthetic approaches have paved novel ways to address future hurdles. This review article highlights the fundamental of COFs, including designing principles, coupling reactions, topologies, structural diversity, synthetic strategies, characterization, growth mechanism, and activation aspects of COFs. Finally, the major challenges and future trends for large-scale COF fabrication are outlined.

Emerging as an outperformed class of metal-organic frameworks (MOFs), square-octahedron (soc) topology MOFs (soc-MOFs) feature superior properties of high porosity, large gas storage capacity, and excellent thermal/chemical stability. We report here an iron based soc-MOF, denoted as Fe-pbpta (H₄pbpta = 4,4′,4″,4‴-(1,4-phenylenbis(pyridine-4,2-6-triyl))-tetrabenzoic acid) possessing a very high Brunauer, Emmett and Teller (BET) surface area of 4,937 m²/g and a large pore volume of 2.15 cm³/g. The MOF demonstrates by far the highest gravimetric uptake of 369 cm³(STP)/g under the DOE operational storage conditions (35 bar and 298 K) and a high volumetric deliverable capacity of 192 cc/cc at 298 K and 65 bar. Furthermore, Fe-pbpta exhibits high thermal and aqueous stability making it a promising candidate for on-board methane storage.