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Benzophenone skeletons containing a carbonyl unit (O=C) have been widely used as electron acceptors in the thermally activated delayed fluorescence (TADF) materials. Herein, we present a novel molecular design concept for TADF materials by transitioning from a carbonyl to an amide (O=C−N) skeleton as the acceptor. The amide unit, compared to its carbonyl counterpart, offers a more stable electronic configuration. Leveraging this insight, we have developed a series of high‐performance TADF molecules based on benzoyl carbazole and carbazoline acceptors. These molecules exhibit exceptionally small singlet‐triplet energy gaps and pronounced aggregation‐enhanced emission properties, achieving photoluminescence quantum yields in neat films as high as 99 %. Consequently, these materials serve as efficient emitters in non‐doped organic light‐eimtting diodes (OLEDs), reaching a maximum quantum efficiency (EQEmax) of up to 26.0 %, significantly higher than the 17.0 % obtained with benzophenone acceptor‐based TADF molecules. Additionally, they have been used as TADF hosts in narrowband red fluorescent OLEDs, setting a record‐high EQEmax of 22.4 %. [ABSTRACT FROM AUTHOR]

Disclosed herein is a RhCl3‐catalyzed peri‐selective C−H/C−H oxidative homo‐coupling of 1‐substituted naphthalenes, which provides a highly efficient and streamlined approach to chalcogen‐embedded anthanthrenes from readily available starting materials. Introducing O, S, and Se into the anthanthrene skeleton leads to gradually increased π–π stacking distances but significantly enhanced π–π overlaps with the growth of the hetero‐atom radius. Moderate π–π distance, overlap area, and intermolecular S−S interactions endow S‐embedded anthanthrene (PTT) with excellent 2D charge‐transport properties. Moreover, the transformation of p‐type to n‐type S‐embedded anthanthrenes is realized for the first time via the S‐atom oxidation from PTT to PTT‐O4. In organic field‐effect transistor devices, PTT derivatives exhibit hole transport with mobilities up to 1.1 cm2 V−1 s−1, while PTT‐O4 shows electron transport with a mobility of 0.022 cm2 V−1 s−1. [ABSTRACT FROM AUTHOR]

The academically widely used electron‐transporting materials (ETMs) typically suffer from low glass transition temperatures (Tg) that could lead to poor device stability. Considering practical applications, we herein put forward a "3D molecular interaction architecture" strategy to design high‐performance ETMs. As a proof‐of‐concept, a type of structurally nontraditional ETMs with the benzo[c]cinnoline (BZC) skeleton have been proposed and synthesized by the C−H/C−H homo‐coupling of N‐acylaniline as the key step. 2,9‐diphenylbenzo[c]cinnoline (DPBZC) exhibits strong intermolecular interactions that feature a 3D architecture, which boosts Tg to exceedingly high 218 °C with a fast electron mobility (μe) of 6.4×10−4 cm2 V−1 s−1. DPBZC‐based fluorescent organic light‐emitting diodes show outstanding electroluminescent performances with an external quantum efficiency of 20.1 % and a power efficiency as high as 70.6 lm W−1, which are superior to those of the devices with the commonly used ETMs. [ABSTRACT FROM AUTHOR]

Disclosed herein is the merging of C−H activation and radical chemistry, enabling rapid access to a structurally diverse family of fused carbohelicenes through the fusion of α‐acetylnaphthalenes with alkynes under oxidative conditions. This cascade process exhibits exquisite chemoselectivity and regioselectivity. The reaction pathway was analyzed by intermediate separations, control experiments, radical trapping, EPR, MALDI‐TOF‐MS, and ESI‐HRMS experiments, and shown to involve a C2−H activation/radical reaction/C8−H activation relay. Carbohelicenes were synthesized with unparalleled ease in a C−H activation/radical reaction/C−H activation sequence starting from α‐acetylnaphthalenes and alkynes. This process exemplifies the high compatibility of ionic and radical transformations. [ABSTRACT FROM AUTHOR]

Reported herein is a rhodium(III)‐catalyzed three‐component annulation reaction of simple pyridines, alkynes, and 1,2‐dichloroethane (DCE), affording a streamlined pathway to diverse ring‐fused pyridiniums. DCE not only serves as a vinyl equivalent but also as an in situ activating agent for pyridine C2−H activation. A cationic five‐membered rhodacycle complex has been isolated and proposed as a possible intermediate. This strategy can be extended to other N‐containing heteroarenes for the synthesis of multiring‐fused pyridiniums. These multicomponent reactions exhibit excellent regioselectivity for 1,3‐diynes, paving a path to the cascade cyclization of 3‐fluoropyridine or N‐methylpyridin‐3‐amine with 1,3‐diynes for the construction of brand‐new tricyclic‐fused pyrano‐ or hydropyridoquinolizinium salts. These ionic fluorophores have been investigated as potential biomarkers. Triple agent: Disclosed herein is a rhodium(III)‐catalyzed multicomponent reaction of simple pyridines, alkynes, and 1,2‐dichloroethane (DCE) to afford a streamlined pathway to diverse ring‐fused pyridiniums. DCE serves as a vinyl equivalent and an in situ activating agent for pyridine C2−H activation, as well as a solvent. [ABSTRACT FROM AUTHOR]

Abstract: By making use of a dual‐chelation‐assisted strategy, a completely regiocontrolled oxidative C−H/C−H cross‐coupling reaction between an N‐acylaniline and a benzamide has been accomplished for the first time. This process constitutes a step‐economic and highly efficient pathway to 2‐amino‐2′‐carboxybiaryl scaffolds from readily available substrates. A Cp*‐free RhCl3/TFA catalytic system was developed to replace the [Cp*RhCl2]2/AgSbF6 system generally used in oxidative C−H/C−H cross‐coupling reactions between two (hetero)arenes (Cp*=pentamethylcyclopentadienyl, TFA=trifluoroacetic acid). The RhCl3/TFA system avoids the use of the expensive Cp* ligand and AgSbF6. As an illustrative example, the procedure developed herein greatly streamlines the total synthesis of the naturally occurring benzo[c]phenanthridine alkaloid oxynitidine, which was accomplished in excellent overall yield. [ABSTRACT FROM AUTHOR]

Nickel can be used to promote oxidative C(sp2)−H/C(sp2)−H cross-coupling between two heteroarenes. The reaction scope can be extended to aromatic carboxamides as the coupling partner. The reaction exhibits high functional-group compatibility and broad substrate scope. The silver oxidant can be recycled to reduce costs and waste, which is very useful for practical applications. [ABSTRACT FROM AUTHOR]

Reported herein is the first example of a transition-metal- catalyzed internal oxidative C-H/C-H cross-coupling between two (hetero)arenes through a traceless oxidation directing strategy. Without the requirement of an external metal oxidant, a wide range of phenols, including phenol-containing natural products, can undergo the coupling with azoles to assemble a large library of highly functionalized 2-(2-hydroxyphenyl)azoles. The route provides an opportunity to rapidly screen white-light-emitting materials. As illustrative examples, two bis(triphenylamine)-bearing 2-(2-hydroxyphenyl) oxazoles, which are difficult to access otherwise, exhibit bright white-light emission, high quantum yield, and thermal stability. Also presented is the first example of the white-light emission, in a single excited-state intramolecular proton transfer system, of 2-(2-hydroxyphenyl)azoles, thus highlighting the charm of C-H activation in the discovery of new organic optoelectronic materials. [ABSTRACT FROM AUTHOR]