Search for: All records

The development of tunable organic photoredox catalysts remains important in the field of photoredox catalysis. A highly modular and tunable family of trianguleniums (azadioxatriangulenium, diazaoxatriangulenium, and triazatriangulenium), and the related [4]helicene quinacridinium have been used as organic photoredox catalysts for photoreductions and photooxidations under visible light irradiation (λ = 518–640 nm). A highlight of this family of photoredox catalysts is their readily tunable redox properties, leading to different reactivities. We report their use as photocatalysts for the aerobic oxidative hydroxylation of arylboronic acids and the aerobic cross-dehydrogenative coupling reaction of N-phenyl-1,2,3,5-tetrahydroisoquinoline with nitromethane through reductive quenching. Furthermore, their potential as photoreduction catalysts has been demonstrated through the catalysis of an intermolecular atom-transfer radical addition via oxidative quenching. These transformations serve as benchmarks to highlight that the easily synthesized trianguleniums, congeners of the acridiniums, are versatile organic photoredox catalysts with applications in both photooxidations and photoreductions.

Long duration storage batteries such as Redox Flow Batteries (RFBs) are promising storage system to address the energy storage requirement that our society will require in the years to come. Recent effort has been focused on the development of metal free and high energy density system such as all‐organic non‐aqueous redox flow batteries (NAORFBs). However high‐voltage NAORFBs currently use distinct anolytes and catholytes, which are separated by a membrane sensitive to osmotic pressure, resulting in rapid capacity and energy density degradation over time. To address this issue, symmetric organic redox flow batteries (SORFBs) have been proposed as an elegant solution. We have introduced dimethoxyquinacridiniums (DMQA⁺) ions as efficient bipolar redox molecules (BRMs) in static H‐cell conditions. In this study, we present the first application of DMQA⁺ions in a complete flow RFB prototype, showcasing their ability to operate with polarity reversal. Key kinetic properties were evaluated through cyclic voltammetry and DFT calculations. While coulombic and energy efficiency metrics were moderate, pegylated DMQA⁺demonstrated impressive capacity retention of over 99.99 % and the capability to operate under polarity inversion, making it a highly attractive choice for grid‐scale, long‐lifespan energy storage applications.

We report the synthesis of a series of ruthenium complexes supported by the phosphine olefin ligand tropPPh₂(trop=5‐H‐dibenzo‐[a,d]cyclohepten‐5‐yl) in the oxidation states 0, +I, and +II, formed via successive one‐electron oxidization steps from Ru⁰(tropPPh₂)₂. The bidentate character of the tropPPh₂ligand and its steric hindrance force the complexes to adopt uncommon geometries, which were investigated by X‐ray diffraction analysis. EPR data of the mononuclear Ru^Icomplex reveal couplings of the unpaired spin with the ruthenium and two phosphorus nuclei, as well as the olefinic protons which show that the spin is mainly localized on the Ru^Icenter.