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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.

Fluorescent dye based nanoparticles (NPs) have received increased interest due to their high brightness and stability. In fluorescence microscopy and assays, high signal to background ratios and multiple channels of...

Cycloparaphenylenes (CPPs) are the smallest possible armchair carbon nanotubes, the properties of which strongly depend on their ring size. They can be further tuned by either peripheral functionalization or by replacing phenylene rings for other aromatic units. Here we show how four novel donor–acceptor chromophores were obtained by incorporating fluorenone or 2‐(9H‐fluoren‐9‐ylidene)malononitrile into the loops of two differently sized CPPs. Synthetically, we managed to perform late‐stage functionalization of the fluorenone‐based rings by high‐yielding Knoevenagel condensations. The structures were confirmed by X‐ray crystallographic analyses, which revealed that replacing a phenylene for a fused‐ring‐system acceptor introduces additional strain. The donor–acceptor characters of the CPPs were supported by absorption and fluorescence spectroscopic studies, electrochemical studies (displaying the CPPs as multi‐redox systems undergoing reversible or quasi‐reversible redox events), as well as by computations. The oligophenylene parts were found to comprise the electron donor units of the macrocycles and the fluorenone parts the acceptor units.

Ultrabright fluorescent nanoparticles (NPs) hold great promise for demanding bioimaging applications. Recently, extremely bright molecular crystals of cationic fluorophores were obtained by hierarchical coassembly with cyanostar anion‐receptor complexes. These small‐molecule ionic isolation lattices (SMILES) ensure spatial and electronic isolation to prohibit aggregation quenching of dyes. We report a simple, one‐step supramolecular approach to formulate SMILES materials into NPs. Rhodamine‐based SMILES NPs stabilized by glycol amphiphiles show high fluorescence quantum yield (30 %) and brightness per volume (5000 M⁻¹ cm⁻¹/nm³) with 400 dye molecules packed into 16‐nm particles, corresponding to a particle absorption coefficient of 4×10⁷ M⁻¹ cm⁻¹. UV excitation of the cyanostar component leads to higher brightness (>6000 M⁻¹ cm⁻¹/ nm³) by energy transfer to rhodamine emitters. Coated NPs stain cells and are thus promising for bioimaging.