Highly stable dioxin-linked metallophthalocyanine covalent organic frameworks

ABSTRACT We report a series of highly stable metallophthalocyanine-based covalent organic frameworks (MPc-dx-COFs) linked by robust 1,4-dioxin bonds constructed through nucleophilic aromatic substitution (SNAr) reaction. The chemical structures and crystallinity of the COFs largely remain unchanged even after treating with boiling water (90 °C), concentrated acids (12 mol/L HCl) or bases (12 mol/L NaOH), oxidizing (30% H2O2) or reducing agents (1 mol/L NaBH4) for three days due to their stable M-Pc building blocks and resilient dioxin linkers. With metallated phthalocyanine active sites regularly arranged in the stable framework structures, MPc-dx-COFs can be directly used as efficient electrocatalysts for the oxygen reduction reaction (ORR) without pyrolysis treatment that has commonly been used in previous studies.