Two-dimensional phthalocyanine-based conjugated covalent organic frameworks: Progress in structures, properties, and applications

Two-dimensional phthalocyanine-based covalent organic frameworks (2D Pc-COFs) synergistically combine the intrinsic photoelectric behavior and M–N4 catalytic centers of phthalocyanine macrocycles with COF advantages, including crystalline porous channels, large specific surface area, and molecularly designable frameworks, enabling broad use in electrocatalysis, photocatalysis, energy conversion and storage, sensing, and biomedicine. Departing from conventional classification schemes based on bonding modes or application fields, this review adopts electron delocalization pathways as the core criterion, dividing 2D Pc-COFs into fully π-conjugated and p–π conjugated systems. This framework encompasses 13 representative linkage types and covers key research advances since the first report of Pc-COFs. Fully π-conjugated systems feature continuous in-plane sp2 π-electron networks that facilitate efficient charge transport, making them well suited for charge-transfer-dominated applications. In contrast, p–π conjugated systems achieve superior chemical stability and enhanced functional tunability through heteroatom-mediated electronic coupling, which enables precise modulation of the active-site microenvironment and reaction selectivity. Furthermore, this review systematically compares their structural features, electronic properties, synthetic strategies, and functional performances, elucidates the underlying structure–property relationships, and outlines current challenges and future research directions. Collectively, this work provides systematic theoretical guidance for the rational design and functional expansion of high-performance Pc-COF materials.