Redox-active covalent organic frameworks (COFs) are promising materials for energy storage devices because of their high density of redox sites, permanent and controlled porosity, high surface areas, and tunable structures. However, the low electrochemical accessibility of their redox-active sites has limited COFbased devices either to thin films (<250 nm) grown on conductive substrates or to thicker films (1 μm) when a conductive polymer is introduced into the COF pores. Electrical energy storage devices constructed from bulk microcrystalline COF powders, eliminating the need for both thin-film formation and conductive polymer guests, would offer both improved capacity and potentially scalable fabrication processes. Here we report on the synthesis and electrochemical evaluation of a new phenazine-based 2D COF (DAPH-TFP COF), as well as its composite with poly(3,4-ethylenedioxythiophene) (PEDOT). Both the COF and its PEDOT composite were evaluated as powders that were solution-cast onto bulk electrodes serving as current collectors. The unmodified DAPH-TFP COF exhibited excellent electrical access to its redox sites, even without PEDOT functionalization, and outperformed the PEDOT composite of our previously reported anthraquinone-based system. Devices containing DAPH-TFP COF were able to deliver both high-energy and high-power densities, validating the promise of unmodified redox-active COFs that are easily incorporated into electrical energy storage devices.
Riboflavin‐derived photocatalysts have been extensively studied in the context of alcohol oxidation. However, to date, the scope of this catalytic methodology has been limited to benzyl alcohols. In this work, mechanistic understanding of flavin‐catalyzed oxidation reactions, in either the absence or presence of thiourea as a cocatalyst, was obtained. The mechanistic insights enabled development of an electrochemically driven photochemical oxidation of primary and secondary aliphatic alcohols using a pair of flavin and dialkylthiourea catalysts. Electrochemistry makes it possible to avoid using O2 and an oxidant and generating H2O2 as a byproduct, both of which oxidatively degrade thiourea under the reaction conditions. This modification unlocks a new mechanistic pathway in which the oxidation of unactivated alcohols is achieved by thiyl radical mediated hydrogen‐atom abstraction.
Riboflavin‐derived photocatalysts have been extensively studied in the context of alcohol oxidation. However, to date, the scope of this catalytic methodology has been limited to benzyl alcohols. In this work, mechanistic understanding of flavin‐catalyzed oxidation reactions, in either the absence or presence of thiourea as a cocatalyst, was obtained. The mechanistic insights enabled development of an electrochemically driven photochemical oxidation of primary and secondary aliphatic alcohols using a pair of flavin and dialkylthiourea catalysts. Electrochemistry makes it possible to avoid using O2 and an oxidant and generating H2O2 as a byproduct, both of which oxidatively degrade thiourea under the reaction conditions. This modification unlocks a new mechanistic pathway in which the oxidation of unactivated alcohols is achieved by thiyl radical mediated hydrogen‐atom abstraction.
We report a novel crystalline supramolecular polybenzobisimidazole (SP-PBBI) capable of providing a twodimensional polymer (2DSP-PBBI) by liquid-phase exfoliation. A regular arrangement of rigid rod-like polybenzobisimidazole (PBBI) chains is achieved by interchain hydrogen bonding. Titration of 2DSP-PBBI with cobalt chloride (CoCl 2 ) using UV-Vis spectroscopy demonstrates the presence of bidentate NO ligands on the PBBI backbone and NO-Co(II) complexation. Imaging analysis using atomic force microscopy (AFM) reveals the planar surface morphology of exfoliated 2DSP-PBBI sheets with lateral dimensions of <1 lm and thickness of <30 nm. The size of the polymer crystal growth is tuned by employing condensation/ precipitation polymerization under nonisothermal conditions.
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