Heterocyclic-linked covalent organic frameworks: Design, synthesis and applications

Covalent organic frameworks (COFs), a growing category of crystalline-structured porous organic compounds, have found an influential position in reticular chemistry. In comparison with solo-bond formed COFs, heterocyclic-linked COFs have benefited from advanced linkages which give them new top-level standards such as superb complexity combined with adjustability, improved framework robustness, excellent structural periodicity and regularity, hydrogen bonding potentiality, functional diversity, exceptional porosity and crystallinity, post-synthetic modification capability, prominent thermal and chemical stability, and proper specific surface area. Due to these outstanding merits, a diverse range of performances in catalysis and photocatalysis processes, sensing materials, separation processes, gas and energy storage and conversion, optoelectronic devices, CO₂ photoreduction, environmental and contaminant remediation and drug delivery have been reported for them. Herein, we exclusively focussed on the design, synthesis, and application of COFs featuring heterocyclic linkages (such as benzoxazole, chromenoquinoline, dioxane, imidazole, imide, oxadiazole, pyrazine, quinoline, thiazole, triazine, benzofuran, phthalocyanine, imidazopyridine, carbamate, thienopyridine) and their benefits and utilizations were showcased.