Research progress on two-dimensional phthalocyanine materials: from molecular design to exploration of multifunctional applications

Two-dimensional (2D) phthalocyanine materials are periodic and ordered material systems formed by extending phthalocyanine or metal phthalocyanine molecules as structural units within a 2D plane through covalent or non-covalent interactions. As planar macrocyclic molecules with an 18π-electron conjugated system, phthalocyanine compounds provide an ideal molecular platform for constructing functional 2D materials due to their high structural stability, excellent physicochemical properties, and flexible molecular modifiability. This article systematically reviews the research progress of 2D phthalocyanine materials from molecular design to functional applications. Firstly, the discovery process, molecular structural characteristics, synthesis methods, and basic properties of phthalocyanine compounds as building blocks are introduced. Then, the structural basis, classification system, and top-down and bottom-up synthesis strategies of 2D phthalocyanine materials are elaborated. In terms of property research, the electronic structure and magnetic tuning mechanism of 2D phthalocyanine materials are discussed in detail, revealing the regulatory effects of central metal type, axial ligand modification, α-site substitution, and strain engineering on the material's band structure, magnetic ground state, and topological properties. The characteristic optical absorption (B-band and Q-band) of phthalocyanine compounds and their tuning strategies in the near-infrared region are systematically analyzed, and the optical application progress of 2D phthalocyanine materials in optoelectronic devices, photodynamic therapy, and other fields is summarized. In addition, the application exploration of these materials in catalytic conversion, gas detection and separation, clean energy storage, and other fields is reviewed, demonstrating their research value as multifunctional platforms. Finally, in response to the current challenges such as limited elemental systems, single network configurations, and insufficient optoelectronic performance, future research directions including expanding the main-group element system, innovating 2D network configurations, and achieving synergistic chemical modification and physical regulation are proposed. This review aims to provide a systematic theoretical reference for the rational design and functional application of 2D phthalocyanine materials.