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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]

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. [ABSTRACT FROM AUTHOR]

A concise, highly efficient palladium-catalyzed direct C-H (hetero)arylation is developed to modularly assemble a diketopyrrolopyrrole ( DTDPP)-based polymer library to screen low-bandgap and near-infrared (NIR) absorbing materials. The DTDPP-based copolymers P1 and P2 with an alternating donor-acceptor-donor-acceptor (D-A-D-A) sequence and the homopolymer P9 exhibit planarity and excellent π-conjugation, which lead to low bandgaps (down to 1.22 eV) as well as strong and broad NIR absorption bands (up to 1000 nm). [ABSTRACT FROM AUTHOR]

Well ‐ connected: The palladium ‐ catalyzed addition of indoles to nitriles affords 3 ‐ acylindoles. The reaction proceeds with high selectivity, wide substrate scope, broadly available starting materials, and an operationally simple procedure. Combination with the palladium ‐ catalyzed intramolecular oxidative coupling of 3 ‐ indolylarylketone gives access to indENoindolones in a one ‐ pot synthesis. [ABSTRACT FROM AUTHOR]

A new approach for the synthesis of C3-symmetric proazaphosphatranes with chirality at the bridging methylene positions is reported. [Copyright &y& Elsevier]

2-Pyridylmethyl ether-directed ortho-C–H olefination of phenols via a seven-membered cyclopalladated intermediate has been disclosed to construct a variety of ortho-alkenyl phenols and ortho-alkyl phenols. [ABSTRACT FROM AUTHOR]

The endeavor to develop high‐performance narrowband blue organic light‐emitting diodes (OLEDs) with low efficiency roll‐off represents an attractive challenge. Herein, we introduce a hetero‐acceptor design strategy centered around the heptagonal diimide (BPI) building block to create an efficient thermally activated delayed fluorescence (TADF) sensitizer. The alignment of a twisted BPI unit and a planar diphenyltriazine (TRZ) fragment imparts remarkable exciton dynamic properties to 26tCz‐TRZBPI, including a fast radiative decay rate (kR) of 1.0×107 s−1 and a swift reverse intersystem crossing rate (kRISC) of 1.8×106 s−1, complemented by a slow non‐radiative decay rate (kNR) of 6.0×103 s−1. Consequently, 26tCz‐TRZBPI facilitates the fabrication of high‐performance narrowband pure‐blue TADF‐sensitized fluorescence OLEDs (TSF‐OLEDs) with a maximum external quantum efficiency (EQEmax) of 24.3 % and low efficiency roll‐off even at a high brightness level of 10000 cd m−2 (EQE10000: 16.8 %). This showcases a record‐breaking external quantum efficiency at a high luminance level of 10000 cd m−2 for narrowband blue TSF‐OLEDs. [ABSTRACT FROM AUTHOR]

The endeavor to develop high‐performance narrowband blue organic light‐emitting diodes (OLEDs) with low efficiency roll‐off represents an attractive challenge. Herein, we introduce a hetero‐acceptor design strategy centered around the heptagonal diimide (BPI) building block to create an efficient thermally activated delayed fluorescence (TADF) sensitizer. The alignment of a twisted BPI unit and a planar diphenyltriazine (TRZ) fragment imparts remarkable exciton dynamic properties to 26tCz‐TRZBPI, including a fast radiative decay rate (kR) of 1.0×107 s−1 and a swift reverse intersystem crossing rate (kRISC) of 1.8×106 s−1, complemented by a slow non‐radiative decay rate (kNR) of 6.0×103 s−1. Consequently, 26tCz‐TRZBPI facilitates the fabrication of high‐performance narrowband pure‐blue TADF‐sensitized fluorescence OLEDs (TSF‐OLEDs) with a maximum external quantum efficiency (EQEmax) of 24.3 % and low efficiency roll‐off even at a high brightness level of 10000 cd m−2 (EQE10000: 16.8 %). This showcases a record‐breaking external quantum efficiency at a high luminance level of 10000 cd m−2 for narrowband blue TSF‐OLEDs. [ABSTRACT FROM AUTHOR]

Described herein is a palladium-catalyzed cross-coupling reaction between nitroarenes and terminal alkynes, offering a facile method for C(sp2)–C(sp) bond formation. The utility of this protocol has been proven by the construction of polycyclic aromatic hydrocarbons (PAHs) and orthogonal cross-coupling. [ABSTRACT FROM AUTHOR]

Narrowband organic light‐emitting diodes (OLEDs) are receiving significant attention and have demonstrated impressive performance in blue and green OLEDs. However, developing high‐performance narrowband red OLEDs remains a highly desired yet challenging task. Herein, we have developed narrowband red fluorescent emitters by utilizing a boron‐dipyrromethene (BODIPY) skeleton in combination with a methyl‐shield strategy. These emitters exhibit small full‐width at half‐maxima (FWHM) ranging from 21 nm (0.068 eV) to 25 nm (0.081 eV) and high photoluminescence quantum yields (ΦPL) ranging from 88.5 % to 99.0 % in toluene solution. Using BODIPY‐based luminescent materials as emitters, high‐performance narrowband red OLEDs have been assembled with external quantum efficiency as high as 18.3 % at 623 nm and 21.1 % at 604 nm. This work represents, to our knowledge, the first successful case of achieving NTSC pure‐red OLEDs with the Commission Internationale de l'Éclairage (CIE) coordinates of [0.67, 0.33] based on conventional fluorescent emitters. [ABSTRACT FROM AUTHOR]

Narrowband organic light‐emitting diodes (OLEDs) are receiving significant attention and have demonstrated impressive performance in blue and green OLEDs. However, developing high‐performance narrowband red OLEDs remains a highly desired yet challenging task. Herein, we have developed narrowband red fluorescent emitters by utilizing a boron‐dipyrromethene (BODIPY) skeleton in combination with a methyl‐shield strategy. These emitters exhibit small full‐width at half‐maxima (FWHM) ranging from 21 nm (0.068 eV) to 25 nm (0.081 eV) and high photoluminescence quantum yields (ΦPL) ranging from 88.5 % to 99.0 % in toluene solution. Using BODIPY‐based luminescent materials as emitters, high‐performance narrowband red OLEDs have been assembled with external quantum efficiency as high as 18.3 % at 623 nm and 21.1 % at 604 nm. This work represents, to our knowledge, the first successful case of achieving NTSC pure‐red OLEDs with the Commission Internationale de l'Éclairage (CIE) coordinates of [0.67, 0.33] based on conventional fluorescent emitters. [ABSTRACT FROM AUTHOR]

An abstract of the study "Cascade Oxidative Coupling/Cyclization: A Gateway to 3-Amino Polysubstituted Five-Membered Heterocycles" by K. Li and colleagues is presented.

An abstract of the article "Rhodium(III)-Catalyzed C(sp3)-H Amidation of 8-Methylquinolines with Amides at Room Temperature" that was published in the previous issue is presented.

Various boron difluoride dyes are synthesized through a one-pot procedure consisting of a catalytic N-heteroarylation followed by complexation with boron trifluoride (15 examples). [ABSTRACT FROM AUTHOR]

Suppressing aggregation‐caused quenching (ACQ) effect and reducing device efficiency roll‐off are both crucial yet challenging for multi‐resonance (MR) emitters. Herein, we put forward a medium‐ring strategy to design efficient MR emitters that feature heptagonal tribenzo[b,d,f]azepine (TBA) donors. The highly twisted conformation enlarges the intermolecular distances between the MR‐emitting cores, and thus suppresses ACQ effect. Meanwhile, the introduction of heptagonal donors enhances spin‐orbital coupling, so as to accelerate reverse intersystem crossing (RISC) process. This medium‐ring strategy gives rise to the first example of blue MR emitter that simultaneously possesses radiative decay rate as fast as 108 s−1 and RISC rate as fast as 106 s−1. Accordingly, DTBA‐B2N3 enables to assemble high‐performance blue organic light‐emitting diodes (OLEDs) with maximum external quantum efficiency (EQEmax) of 30.9 % and alleviated efficiency roll‐off (EQE1000: 20.5 %). [ABSTRACT FROM AUTHOR]

Suppressing aggregation‐caused quenching (ACQ) effect and reducing device efficiency roll‐off are both crucial yet challenging for multi‐resonance (MR) emitters. Herein, we put forward a medium‐ring strategy to design efficient MR emitters that feature heptagonal tribenzo[b,d,f]azepine (TBA) donors. The highly twisted conformation enlarges the intermolecular distances between the MR‐emitting cores, and thus suppresses ACQ effect. Meanwhile, the introduction of heptagonal donors enhances spin‐orbital coupling, so as to accelerate reverse intersystem crossing (RISC) process. This medium‐ring strategy gives rise to the first example of blue MR emitter that simultaneously possesses radiative decay rate as fast as 108 s−1 and RISC rate as fast as 106 s−1. Accordingly, DTBA‐B2N3 enables to assemble high‐performance blue organic light‐emitting diodes (OLEDs) with maximum external quantum efficiency (EQEmax) of 30.9 % and alleviated efficiency roll‐off (EQE1000: 20.5 %). [ABSTRACT FROM AUTHOR]

Synthesis of indolylarylketones proceeds with high selectivity and for a wide substrate scope by the presented operationally simple procedure. [ABSTRACT FROM AUTHOR]

It is demonstrated that 2-pyridylmethyl ether can serve as an efficient directing group for amino acid accelerated ortho-C-H olefination of phenols via a seven-membered cyclopalladated intermediate. [ABSTRACT FROM AUTHOR]

Transition metal-mediated C-H bond activation and functionalization represent one of the most straightforward and powerful tools in modern organic synthetic chemistry. Bi(hetero)aryls are privileged π-conjugated structural cores in biologically active molecules, organic functional materials, ligands, and organic synthetic intermediates. The oxidative C-H/C-H coupling reactions between two (hetero)arenes through 2-fold C-H activation offer a valuable opportunity for rapid assembly of diverse bi(hetero)aryls and further exploitation of their applications in pharmaceutical and material sciences. This review provides a comprehensive overview of the fundamentals and applications of transition metal-mediated/catalyzed oxidative C-H/C-H coupling reactions between two (hetero)arenes. The substrate scope, limitation, reaction mechanism, regioselectivity, and chemoselectivity, as well as related control strategies of these reactions are discussed. Additionally, the applications of these established methods in the synthesis of natural products and exploitation of new organic functional materials are exemplified. In the last section, a short introduction on oxidant- or Lewis acid-mediated oxidative Ar-H/Ar-H coupling reactions is presented, considering that it is a very powerful method for the construction of biaryl units and polycylic arenes. [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]

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 development of intramolecular‐lock strategy is an appealing task for designing efficient thermally activated delayed fluorescence (TADF) molecules, but only limited examples have been reported so far. Herein we present a "medium ring"‐lock strategy to develop TADF emitters for improving the efficiency of organic light‐emitting diodes (OLEDs). The installation of an electron‐deficient heptagonal diimide lock onto a highly rotatable biphenyl‐based emitter not only enhances electron‐withdrawing ability of acceptor that decreases singlet‐triplet energy gap (ΔEST), but also endows the skeleton with modest rigidity and flexibility that increases photoluminescence quantum yield (PLQY) in neat film. In particular, the integration of the diimide lock also leads to an increase in horizontal orientation factor (Θ//) from 69 % to 83 %. Consequently, this modified intramolecular‐lock strategy enables an efficient TADF emitter to assemble high‐performance non‐doped OLEDs with a high external quantum efficiency of 26.2 % and a power efficiency of 76.6 lm W−1. [ABSTRACT FROM AUTHOR]

The development of intramolecular‐lock strategy is an appealing task for designing efficient thermally activated delayed fluorescence (TADF) molecules, but only limited examples have been reported so far. Herein we present a "medium ring"‐lock strategy to develop TADF emitters for improving the efficiency of organic light‐emitting diodes (OLEDs). The installation of an electron‐deficient heptagonal diimide lock onto a highly rotatable biphenyl‐based emitter not only enhances electron‐withdrawing ability of acceptor that decreases singlet‐triplet energy gap (ΔEST), but also endows the skeleton with modest rigidity and flexibility that increases photoluminescence quantum yield (PLQY) in neat film. In particular, the integration of the diimide lock also leads to an increase in horizontal orientation factor (Θ//) from 69 % to 83 %. Consequently, this modified intramolecular‐lock strategy enables an efficient TADF emitter to assemble high‐performance non‐doped OLEDs with a high external quantum efficiency of 26.2 % and a power efficiency of 76.6 lm W−1. [ABSTRACT FROM AUTHOR]

An approach allowing remote editing of stacked aromatic assemblies for heteroannular C−H functionalization would represent a transformative chemical toolbox that may make the diversification of complex molecules in a straightforward manner. However, such a C−H activation is usually less kinetically and thermodynamically favorable than homoannular ortho C−H activation and remains a fundamental challenge. Herein we disclose an engineer's approach, using a transient ligand as an interim bridge between two aryl rings (analogues to mountaintops) to anchor the metal center on the remote heteroannular C−H bond. As a proof‐of‐concept, we present the palladium‐catalyzed heteroannular C−H olefination of stacked aromatic assemblies with olefins and allylation with vinyl acetates using L‐tert‐leucine acid as a transient ligand. Mechanistic investigations suggest an unusual olefin coordination‐promoted interannular palladium migration process determinative for reversal of the site‐selectivity. [ABSTRACT FROM AUTHOR]

An approach allowing remote editing of stacked aromatic assemblies for heteroannular C−H functionalization would represent a transformative chemical toolbox that may make the diversification of complex molecules in a straightforward manner. However, such a C−H activation is usually less kinetically and thermodynamically favorable than homoannular ortho C−H activation and remains a fundamental challenge. Herein we disclose an engineer's approach, using a transient ligand as an interim bridge between two aryl rings (analogues to mountaintops) to anchor the metal center on the remote heteroannular C−H bond. As a proof‐of‐concept, we present the palladium‐catalyzed heteroannular C−H olefination of stacked aromatic assemblies with olefins and allylation with vinyl acetates using L‐tert‐leucine acid as a transient ligand. Mechanistic investigations suggest an unusual olefin coordination‐promoted interannular palladium migration process determinative for reversal of the site‐selectivity. [ABSTRACT FROM AUTHOR]

Multi‐resonance boron‐nitrogen‐containing thermally activated delayed fluorescence (MR‐TADF) emitters have experienced great success in assembling narrowband organic light‐emitting diodes (OLEDs). However, the slow reverse intersystem crossing rate (kRISC) of MR‐emitters (103–105 s−1) that will lead to severe device efficiency roll‐off has received extensive attention and remains a challenging issue. Herein, we put forward a "space‐confined donor‐acceptor (SCDA)" strategy to accelerate RISC process. The introduction of SCDA units onto the MR‐skeleton induces intermediate triplet states, which leads to a multichannel RISC process and thus increases kRISC. As illustrated examples, efficient MR‐emitters have been developed with a sub‐microsecond delayed lifetime and a high kRISC of 2.13×106 s−1, which enables to assemble high‐performance OLEDs with a maximum external quantum efficiency (EQEmax) as high as 32.5 % and an alleviated efficiency roll‐off (EQE1000: 22.9 %). [ABSTRACT FROM AUTHOR]

Multi‐resonance boron‐nitrogen‐containing thermally activated delayed fluorescence (MR‐TADF) emitters have experienced great success in assembling narrowband organic light‐emitting diodes (OLEDs). However, the slow reverse intersystem crossing rate (kRISC) of MR‐emitters (103–105 s−1) that will lead to severe device efficiency roll‐off has received extensive attention and remains a challenging issue. Herein, we put forward a "space‐confined donor‐acceptor (SCDA)" strategy to accelerate RISC process. The introduction of SCDA units onto the MR‐skeleton induces intermediate triplet states, which leads to a multichannel RISC process and thus increases kRISC. As illustrated examples, efficient MR‐emitters have been developed with a sub‐microsecond delayed lifetime and a high kRISC of 2.13×106 s−1, which enables to assemble high‐performance OLEDs with a maximum external quantum efficiency (EQEmax) as high as 32.5 % and an alleviated efficiency roll‐off (EQE1000: 22.9 %). [ABSTRACT FROM AUTHOR]

The development of high‐performance blue organic light‐emitting diodes (OLEDs) remains a challenging task. While exploiting new blue emitters has attracted great interest, developing host materials that considerably determine device performance obviously lags behind. Herein, we present an ease of access to the structurally diverse benzoheteroaromatic‐fused pyridine skeletons by the iridium‐catalyzed intramolecular C−H/C−H coupling reaction, which unlocks an unparalleled opportunity to rapidly assemble a library of pyridine‐fused bipolar host materials. As an illustrated example, the benzo[4,5]thieno[2,3‐b]pyridine skeleton (BTP) has been made to a pseudo‐symmetric host (DCz‐BTP). The merging of a pyridine fragment enables strong intermolecular interactions, leading to satisfactory bipolar transporting properties. Utilizing DCz‐BTP as the host, blue thermally activated delayed fluorescent OLEDs (TADF‐OLEDs) exhibit a low turn‐on voltage of 2.8 V and a high maximum external quantum efficiency (EQEmax) of 29.0 % and blue TADF‐sensitized florescent OLEDs (TSF‐OLEDs) give an EQEmax as high as 20.5 %, revealing the potential of the BTP skeleton for the construction of high‐performance host materials. [ABSTRACT FROM AUTHOR]

The development of high‐performance blue organic light‐emitting diodes (OLEDs) remains a challenging task. While exploiting new blue emitters has attracted great interest, developing host materials that considerably determine device performance obviously lags behind. Herein, we present an ease of access to the structurally diverse benzoheteroaromatic‐fused pyridine skeletons by the iridium‐catalyzed intramolecular C−H/C−H coupling reaction, which unlocks an unparalleled opportunity to rapidly assemble a library of pyridine‐fused bipolar host materials. As an illustrated example, the benzo[4,5]thieno[2,3‐b]pyridine skeleton (BTP) has been made to a pseudo‐symmetric host (DCz‐BTP). The merging of a pyridine fragment enables strong intermolecular interactions, leading to satisfactory bipolar transporting properties. Utilizing DCz‐BTP as the host, blue thermally activated delayed fluorescent OLEDs (TADF‐OLEDs) exhibit a low turn‐on voltage of 2.8 V and a high maximum external quantum efficiency (EQEmax) of 29.0 % and blue TADF‐sensitized florescent OLEDs (TSF‐OLEDs) give an EQEmax as high as 20.5 %, revealing the potential of the BTP skeleton for the construction of high‐performance host materials. [ABSTRACT FROM AUTHOR]

Oxidative transformations of phenols have attracted significant attention of chemists due to their importance in biological process and organic synthesis. In contrast to the relatively well-developed oxygenation and coupling reactions of phenols, the highly efficient and selective oxidative ring cleavage of phenols is under-represented. This work describes a novel CuCl-catalyzed tandem homocoupling/skeletal rearrangement of phenols that realizes the cleavage of the phenol ring by using air or Ag2CO3 as the oxidant. Interestingly, simply changing the oxidant to K2S2O8 results in the oxidative coupling/cyclization of phenols to give dibenzofurans. These results set an important precedent of oxidant-controlled catalytic transformations of phenols. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu(I) exciplexes are developed using several Cu(I) carbene-metal-amide (CMA) complexes as donors. • Donor-dependent TADF emissions from copper(I)-perturbed through-space charge transfer excited states. • Narrowband electroluminescence with high EQEs of up to 24.9%. Organo-copper(I) emitters are promising cost-effective candidates as triplet-harvesting dopants in organic light-emitting diodes (OLEDs). To date, the mainstream design of Cu(I) emitters depends on ligand engineering to modify intramolecular charge transfer and thus modulate the related optoelectronic properties. However, little is known on luminescent Cu(I) systems based on intermolecular charge transfer. For the first time, the proof-of-concept Cu(I) exciplexes were developed employing a triazine-containing molecule DMIC-TRZ as an acceptor and several Cu(I)-based carbene-metal-amide (CMA) complexes as donors. The formation of these exciplexes is strongly associated with d-orbital participation of Cu atom on the highest occupied molecular orbital of CMA complexes to match with the acceptor DMIC-TRZ. These Cu(I) exciplexes not only displayed donor-dependent emission colors spanning from sky blue to red but also exhibited distinct thermally activated delayed fluorescence (TADF) via copper(I)-perturbed through-space charge transfer (TSCT). The OLEDs adopting the Cu(I) exciplexes as emitters delivered good external quantum efficiency (EQE) of up to 10.9%. Furthermore, the use of these Cu(I) exciplexes as hosts for multi-resonance TADF emitters delivered narrowband electroluminescence with high EQEs of up to 24.9%, superior to the reference OLEDs based on the common host. [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]

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]

Over the past few years, transition metal-mediated oxidative cross-coupling reactions have emerged as a versatile method to construct C–C bonds. However, most of the precedents require high-priced precious metal catalysts such as Rh, Pd, and Ru in combination with a stoichiometric amount of metal oxidant including copper and silver salt. Recently, stoichiometric copper or silver salt-mediated oxidative C–H/C–H cross-coupling reactions in the absence of high-priced metal catalyst have shown up prominently. This short review covers the latest progress in the applications of this emerging strategy, highlights their advantages and limitations, and provides a comprehensive overview on existing procedures and employed methodologies. [ABSTRACT FROM AUTHOR]

The emitting layer based on a host–guest system plays a crucial role in organic light‐emitting diodes (OLEDs). While emitters have witnessed rapid progress in structural diversity, hosts still rely heavily on traditional structures and are underdeveloped. Herein a "medium‐ring" strategy has been put forward to design structurally nontraditional host molecules, which are not only rotatable enough to suppress close π–π stacking, thus reducing exciton annihilation, but also rigid enough to prevent excessive conformational flipping, thus inhibiting non‐radiative decay. Accordingly, a brand‐new type of bipolar hosts with a twisted "butterfly‐shaped heptagonal acceptor (EtBP), which features an electron‐deficient benzophenone fragment with a flexible ethylidene bridge, has been developed. With satisfactory morphological stability and well‐balanced hole‐ and electron‐transporting properties, the EtBP‐based bipolar hosts enable high‐performance RGB phosphorescent OLEDs with small efficiency roll‐off, which are superior to those of acyclic benzophenone‐based devices. [ABSTRACT FROM AUTHOR]

The emitting layer based on a host–guest system plays a crucial role in organic light‐emitting diodes (OLEDs). While emitters have witnessed rapid progress in structural diversity, hosts still rely heavily on traditional structures and are underdeveloped. Herein a "medium‐ring" strategy has been put forward to design structurally nontraditional host molecules, which are not only rotatable enough to suppress close π–π stacking, thus reducing exciton annihilation, but also rigid enough to prevent excessive conformational flipping, thus inhibiting non‐radiative decay. Accordingly, a brand‐new type of bipolar hosts with a twisted "butterfly‐shaped heptagonal acceptor (EtBP), which features an electron‐deficient benzophenone fragment with a flexible ethylidene bridge, has been developed. With satisfactory morphological stability and well‐balanced hole‐ and electron‐transporting properties, the EtBP‐based bipolar hosts enable high‐performance RGB phosphorescent OLEDs with small efficiency roll‐off, which are superior to those of acyclic benzophenone‐based devices. [ABSTRACT FROM AUTHOR]

The copper-mediated tandem oxidativeC(sp2)–H/C(sp)–Hcross-coupling and intramolecular annulation of arenes with terminalalkynes has been developed, which offers a highly efficient approachto the 3-methyleneisoindolin-1-one scaffold. In this oxidative couplingprocess, Cu(OAc)2acts as both the promoter and the terminaloxidant. This protocol features a wide substrate scope; high functionalgroup tolerance; exclusive chemo-, regio-, and stereoselectivity;and simple, easily available, and inexpensive reaction system. Thetransformation has demonstrated for the first time that Cu(OAc)2can be renewable after undergoing an oxidative reaction. [ABSTRACT FROM AUTHOR]

Abstract: New squaraine-based chemosensors SQ1 and SQ2 functionalized with 2-picolyl units were first synthesized and used as highly selective and sensitive colorimetric and fluorometric dual-channel sensors for Cu2+-specific recognition in aqueous systems. Among a series of individual metal ions, only Cu2+ could result in dramatic color changes. We also evaluated their capability of biological applications and found that SQ2 could be successfully employed as a Cu2+-selective probe in the fluorescence imaging of living cells. [Copyright &y& Elsevier]

Herein disclosed is the first example of diarylation/annulation of benzoic acids via an iridium catalyst system. This protocol provides a step‐economic and highly efficient pathway to 1‐aryl, 1,3‐diaryl, 1,7‐diaryl and 1,3,7‐triaryl spirobifluorenes from readily available starting materials. The applications of multi‐aryl spirobifluorenes as pure hydrocarbon (PHC) hosts for red, green, and blue (RGB) phosphorescent organic light‐emitting diodes (PhOLEDs) were explored. Due to high triplet energies, 1,3‐diaryl spirobifluorenes exhibit the potential as the host material of blue PhOLEDs. 1,7‐Diaryl spirobifluorene can serve as the host of green PhOLEDs. 1,3,7‐Triaryl spirobifluorene is a high‐performance host for red PhOLEDs, which exhibits a high external quantum efficiency (EQE) up to 27.3 %. This work not only exemplifies the great potential of multi‐aryl spirobifluorenes as PHC hosts, but also offers a new approach for the synthesis of these PHC hosts. [ABSTRACT FROM AUTHOR]

Herein disclosed is the first example of diarylation/annulation of benzoic acids via an iridium catalyst system. This protocol provides a step‐economic and highly efficient pathway to 1‐aryl, 1,3‐diaryl, 1,7‐diaryl and 1,3,7‐triaryl spirobifluorenes from readily available starting materials. The applications of multi‐aryl spirobifluorenes as pure hydrocarbon (PHC) hosts for red, green, and blue (RGB) phosphorescent organic light‐emitting diodes (PhOLEDs) were explored. Due to high triplet energies, 1,3‐diaryl spirobifluorenes exhibit the potential as the host material of blue PhOLEDs. 1,7‐Diaryl spirobifluorene can serve as the host of green PhOLEDs. 1,3,7‐Triaryl spirobifluorene is a high‐performance host for red PhOLEDs, which exhibits a high external quantum efficiency (EQE) up to 27.3 %. This work not only exemplifies the great potential of multi‐aryl spirobifluorenes as PHC hosts, but also offers a new approach for the synthesis of these PHC hosts. [ABSTRACT FROM AUTHOR]

The pursuit of efficient synthetic route to thienoacenes represents an appealing yet challenging task in the fields of both organic synthetic chemistry and organic functional materials. In this work, we disclose a rhodium‐catalyzed cascade C−H annulation of phenacyl phosphoniums with (benzo)thiophenes via a Heck‐type pathway to provide a new class of planar thienoacenes, which involves the formation of three Caryl‐Caryl bonds and one Caryl−O bond in a single operation. The neutral S,O‐heteroacenes exhibit superior stability and adopt a herringbone‐like packing mode with efficient π–π stacking in the crystals, suggesting their potential in organic semiconducting materials. This work first exemplifies the superiority of cascade oxidative C−H annulation involving a Heck‐type pathway in the development of concise access to heteroacenes. [ABSTRACT FROM AUTHOR]

The pursuit of efficient synthetic route to thienoacenes represents an appealing yet challenging task in the fields of both organic synthetic chemistry and organic functional materials. In this work, we disclose a rhodium‐catalyzed cascade C−H annulation of phenacyl phosphoniums with (benzo)thiophenes via a Heck‐type pathway to provide a new class of planar thienoacenes, which involves the formation of three Caryl‐Caryl bonds and one Caryl−O bond in a single operation. The neutral S,O‐heteroacenes exhibit superior stability and adopt a herringbone‐like packing mode with efficient π–π stacking in the crystals, suggesting their potential in organic semiconducting materials. This work first exemplifies the superiority of cascade oxidative C−H annulation involving a Heck‐type pathway in the development of concise access to heteroacenes. [ABSTRACT FROM AUTHOR]

A new type of triazolotriazine acceptor has been designed to construct highly efficient TADF materials by fusing triazine and triazole together and achieve the state-of-the-art performance yellow TSF-OLEDs. [Display omitted] Thermally activated delayed fluorescence (TADF) sensitized fluorescent organic light-emitting diodes (TSF-OLEDs) have shown great potential for the realization of high efficiency with low efficiency roll-off and good color purity. However, the superior examples of TSF-OLEDs are still limited up to now. Herein, a trade-off strategy is presented for designing efficient TADF materials and achieving high-performance TSF-OLEDs via the construction of a new type of triazolotriazine (TAZTRZ) acceptor. The enhanced electron-withdrawing ability of TAZTRZ acceptor, fused by triazine (TRZ) and triazole (TAZ) together, enables TADF luminogens with small singlet-triplet energy gap (Δ E ST) values. Meanwhile, the increased planarity from the TRZ-phenyl linkage (6:6 system) to the TAZ-phenyl linkage (5:6 system) can compensate the decrease of oscillator strength (f) while lowing Δ E ST , thus achieving a trade-off between small Δ E ST and high f. As a result, the related TSF-OLED achieved an extremely low turn-on voltage of 2.1 V, an outstanding maximum external quantum efficiency (EQE max) of 23.7% with small efficiency roll-off (EQE 1000 of 23.2%; EQE 5000 of 20.6%) and an impressively high maximum power efficiency of 82.1 lm W−1, which represents the state-of-the-art performance for yellow TSF-OLEDs. [ABSTRACT FROM AUTHOR]

Disclosed here is a palladium‐catalyzed direct [4+1] spiroannulation of ortho‐C−H bonds of naphthols with cyclic diaryliodonium salts to construct spirofluorenyl naphthalenones (SFNP) under mild reaction conditions. This spiroannulation directly transforms the hydroxy group into a carbonyl group, and also tolerates reactive functional groups such as the halo groups, which provide an opportunity to rapidly assemble structurally new thermally activated delayed fluorescent (TADF) materials that feature a carbonyl group with an adjacent spirofluorenyl unit as the acceptor. As an illustrated example, the OLED device utilizing the assembled DMAC‐SFNP as the host material exhibits a low turn‐on voltage of 2.5 V and an ultra‐high external quantum efficiency of 32.2 %. This work provides inspiration for structurally new TADF materials, and also displays the potential of C−H activation as a synthetic strategy for the innovation of optoelectronic materials. [ABSTRACT FROM AUTHOR]

Disclosed here is a palladium‐catalyzed direct [4+1] spiroannulation of ortho‐C−H bonds of naphthols with cyclic diaryliodonium salts to construct spirofluorenyl naphthalenones (SFNP) under mild reaction conditions. This spiroannulation directly transforms the hydroxy group into a carbonyl group, and also tolerates reactive functional groups such as the halo groups, which provide an opportunity to rapidly assemble structurally new thermally activated delayed fluorescent (TADF) materials that feature a carbonyl group with an adjacent spirofluorenyl unit as the acceptor. As an illustrated example, the OLED device utilizing the assembled DMAC‐SFNP as the host material exhibits a low turn‐on voltage of 2.5 V and an ultra‐high external quantum efficiency of 32.2 %. This work provides inspiration for structurally new TADF materials, and also displays the potential of C−H activation as a synthetic strategy for the innovation of optoelectronic materials. [ABSTRACT FROM AUTHOR]

Introduction of a weak electron-donating or electron-withdrawing functional groups with steric hindrance to the molecular skeleton of thermally activated delayed fluorescence (TADF) emitters is necessary to finely tune singlet and triplet energy levels and suppress efficiency roll-off at high brightness without significantly changing their emitting colors. Herein, the weak electron-withdrawing succinimide (SI) is introduced for the first time to carbazole-benzonitrile (CzBN) skeletons as an acceptor through the connection of nitrogen atom of imides to the para -position of the cyano group. The resulting imide-modified TADF emitter SI-DtCzBN exhibits a short delayed fluorescence lifetime (τ d) of 0.85 μs in neat film and 3.4 μs in doped film with a high photoluminescence quantum yield (PLQY) of 80% owing to its moderate singlet-triplet energy gap (Δ E ST) of 0.08 eV. OLED devices based on SI-DtCzBN as an emitter show a pure blue emission at 455 nm with EQE max of 15.9% and extremely low efficiency roll-off. Thermally activated sensitized fluorescence OLEDs (TSF-OLEDs) are also fabricated by the utilization of SI-DtCzBN as a sensitizer and ν -DABNA as an emitter, which display blue electroluminescence with the peak at 472 nm, a narrow FWHM of 21 nm, and EQE max of 13.6%. [Display omitted] • Imides are introduced to carbazole-benzonitrile skeletons for the fine-tuning of singlet and triplet energy levels. • The imide-modified TADF emitter exhibits short τ d of 0.85 μ s and high PLQY of 80% owing to its moderate Δ E ST of 0.08 eV. • OLED based on the target emitter displays a pure blue emission at 455 nm with EQE max of 15.9% and low efficiency roll-off. [ABSTRACT FROM AUTHOR]

Despite the aesthetically appealing structures and tantalizing physical and chemical properties, zigzag hydrocarbon belts and their heteroatom‐embedded analogues remain challenging synthetic targets. We report herein the synthesis of diverse O/N‐doped zigzag hydrocarbon belts based on selective bridging of the fjords of resorcin[4]arene derivatives through intramolecular SNAr and palladium‐catalyzed intermolecular C−N bond formation reactions. Preorganized conformations of mono‐macrocyclic, half‐belt and quasi‐belt compounds were revealed to facilitate cyclization reactions to construct heteroatom‐linked octahydrobelt[8]arenes. The acquired products had strained square‐prism‐shaped belt structures in which all six‐membered heterocyclic rings adopted an unusual boat conformation with equatorially configured alkyl groups. The unprecedented heteroatom‐bearing belts also exhibited different photophysical and redox properties to those of octahydrobelt[8]arene analogues. [ABSTRACT FROM AUTHOR]

Described herein is a strategy to construct cationic azahelicenes through the three‐component annulation reaction of isoquinoline, indole, and 1,2‐dichloroethane (DCE), in which DCE serves as an in situ activating agent for C1−H activation of isoquinoline, a vinyl equivalent, and a solvent. This in situ activation annulation reaction features a facile one‐step synthesis and complete regioselectivity. The complete regioselectivity of C1 over C3 for the isoquinoline ring paves a path to the helical structure in a highly ordered sequence. One of the synthesized ionic [5]azahelicenium fluorophores exhibits the potential to serve as a mitochondria‐targeted biomarker with good photostability and low cytotoxicity. [ABSTRACT FROM AUTHOR]

Despite the aesthetically appealing structures and tantalizing physical and chemical properties, zigzag hydrocarbon belts and their heteroatom‐embedded analogues remain challenging synthetic targets. We report herein the synthesis of diverse O/N‐doped zigzag hydrocarbon belts based on selective bridging of the fjords of resorcin[4]arene derivatives through intramolecular SNAr and palladium‐catalyzed intermolecular C−N bond formation reactions. Preorganized conformations of mono‐macrocyclic, half‐belt and quasi‐belt compounds were revealed to facilitate cyclization reactions to construct heteroatom‐linked octahydrobelt[8]arenes. The acquired products had strained square‐prism‐shaped belt structures in which all six‐membered heterocyclic rings adopted an unusual boat conformation with equatorially configured alkyl groups. The unprecedented heteroatom‐bearing belts also exhibited different photophysical and redox properties to those of octahydrobelt[8]arene analogues. [ABSTRACT FROM AUTHOR]

Described herein is a strategy to construct cationic azahelicenes through the three‐component annulation reaction of isoquinoline, indole, and 1,2‐dichloroethane (DCE), in which DCE serves as an in situ activating agent for C1−H activation of isoquinoline, a vinyl equivalent, and a solvent. This in situ activation annulation reaction features a facile one‐step synthesis and complete regioselectivity. The complete regioselectivity of C1 over C3 for the isoquinoline ring paves a path to the helical structure in a highly ordered sequence. One of the synthesized ionic [5]azahelicenium fluorophores exhibits the potential to serve as a mitochondria‐targeted biomarker with good photostability and low cytotoxicity. [ABSTRACT FROM AUTHOR]