Mechanochemistry-Driven Construction of Aza-fused π-Conjugated Networks Toward Enhanced Energy Storage

The current approaches toward synthesis of conjugated microporous polymers (CMPs) functionalized by aza-fused functionalities are still limited to solution-based procedures or ionothermal polymerizations, which requires monomers with rigid/high steric hindrance structures and multiple reactive sites and extra arene-based cross-linkers, and generated CMPs with low content of aza-fused functionalities. Herein, a facile mechanochemistry-driven procedure is developed capable of affording a series of CMPs composed of abundant aza-fused functionalities via a homocoupling process. Simple and linear aromatic bromide monomers with phenanthroline or bipyridine cores are deployed as the starting materials, which can coordinate on the metal surface to form 3D assembly and be polymerized in the presence of catalytic amount of magnesium powder driven by mechanochemical treatment under solvent- and additive-free conditions. CMPs composed of solely phenanthroline or bipyridine moieties being connected by C–C bonds are afforded with high surface areas (up to 789 m² g^-1), permanent and hierarchical porous architectures (micro- and mesopores), abundant aza-fused moieties, and π-conjugated networks. All these unique features made them promising candidates as supercapacitors, which exhibit outstanding electrocapacitive performance with a capacitance of 296 F g^-1 at 0.3 A g^-1 and capacitance retention of 103% for 5000 cycles at 5 A g^-1.