Shape-persistent phthalocyanine cages

Phthalocyanine (Pc), an electro-redox active moiety, has many attractive properties stemming from its large aromatic system and ability to act as a catalyst in electrochemical reactions, such as the CO2 reduction reaction (CO2RR). However, due to the synthetic challenge related to geometric requirements and poor solubility (strong aggregation), discrete shape-persistent cages consisting of site-isolated, readily accessible Pc moieties have not been available. Here, we report the synthesis of Zn- and Ni-metallated Pc-based molecular cages via one-step dynamic spiroborate linkage formation in high yields. The ZnPc cage structure is unambiguously elucidated at the atomic level by single-crystal X-ray diffraction. Moreover, owing to the site-isolated redox-active metal centers, readily accessible intrinsic cavity, and shape-persistent backbone, the Ni-metallated Pc (NiPc) cage exhibits high catalytic efficiency, selectivity, and stability, superior to the non-caged control molecules in electrocatalytic CO2RR. [Display omitted] •Well-defined phthalocyanine-based molecular cages are synthesized in high yields•The one-step cage synthesis is accomplished via dynamic spiroborate exchange•The cage structure is elucidated by single-crystal X-ray diffraction•Ni-metallated cage shows high selectivity in electrocatalytic CO2RR in broad voltages Hu et al. report the one-step synthesis of phthalocyanine-based molecular cages via dynamic spiroborate exchange. Owing to the site-isolated metal centers, readily accessible intrinsic cavity, and shape-persistent backbone, the nickel-metallated cage exhibits notable electrocatalytic CO2RR performance, demonstrating the feasibility of incorporating catalytically active moieties into cage structures to achieve enhanced catalytic activity.