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

Abstract

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.

Fully Conjugated Poly(phthalocyanine) Scaffolds Derived from a Mechanochemical Approach Towards Enhanced Energy Storage

“…Initial procedures were performed under high vacuum and relatively high temperatures (>200 °C) to allow for the evaporation of the small molecule monomers [24] . Then this bottom‐up technique was further extended to mechanochemistry‐driven procedures, [25, 26] which achieved the benzene ring knitting via the Mg‐promoted aromatic halides polymerization under ambient conditions with the large energy input from the ball milling treatment and extra electron sources from the Mg catalyst, enabling the carbon nucleophile (e.g., Grignard reagent) intermediate formation [27, 28] . Previously reported works demonstrated that metals (Cu or Mg) and Grignard reagents could initiate the carbon nucleophile formation from aromatic nitriles and catalyze the subsequent cyclization reactions to synthesize small molecule Pc derivatives [3, 28] .…”

Tuning the Photocatalytic Activity through Linkages of Porous Conjugated Polymers Based on Triazines for a Selective Oxidation Reaction

“…[ 1 ] In contrast to inorganic photocatalysts, tunable structures with miscellaneous units and preparation pathways will increase the potential exploration value of porous organic polymers by facilitating categories diversity and properties variability. [ 2 ] In particular, conjugated polymers as metal‐free materials are a burgeoning development area because of some mutually outstanding features such as easy functionalization, large specific surface area, Earth‐abundant nature, and structural tailorability. [ 3 ] However, conjugated polymers like conjugated microporous polymers (CMPs) and covalent organic frameworks (COFs) possess plentiful intrinsic advantages as photocatalysts.…”

Construction of Nitrogen‐abundant Graphyne Scaffolds via Mechanochemistry‐Promoted Cross‐Linking of Aromatic Nitriles with Carbide Toward Enhanced Energy Storage

“…The development of electrochemical storage devices with improved efficiency and stability represents one of the most attractive strategies to solve the global potential energy crisis issue, [19][20][21] among which supercapacitors have gained considerable attention due to their rapid charge/discharge rate and high power density. [22][23] Notably, the π-conjugated structure, permanent porous property, and abundant defects within the networks of graphyne materials made them promising candidate as electrode materials in supercapacitor applications. [24] The graphyne materials derived from the mechanochemical treatment of CaC 2 and polyhalogenated hydrocarbons, possessing the surface area of 500-700 m 2 g −1 , displayed the supercapacitance of ≈50-80 F g −1 at the current density of 1 A g −1 .…”

“…[15] A highly preferable method of improving the capacitive performance of graphyne materials is via heteroatom doping (e.g., nitrogen-doping), which has been shown to enhance the capacitance of related materials by introducing pseudo capacitances and engineering wettability. [23,[25][26] In addition, significantly improved electrical conductivity was also achieved by nitrogendoping within the material scaffolds, which could facilitate the formation of a localized electron-donor state near the Fermi level. [27] However, there are still limited approaches capable of affording abundant nitrogen moieties-involved graphyne materials.…”