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Owing to the high technology maturity of thermally activated delayed fluorescence (TADF) emitter design with a specific molecular shape, extremely high-performance organic light-emitting diodes (OLEDs) have recently been achieved

Three pyridine-carbonitrile (PPC) fluorophores with amine-type donors, carbazole, tert-butylcarbazole, and spiroacridine have been designed and synthesized. A high-performance green OLED based on SAcmPPC dopant exhibited an external quantum efficiency of 37.2%.

Transforming triplet excitons into singlet excitons is a topic of great interest to material scientists in order to surpass the exciton utilization efficiency (EUE) limit of 25% in electro-fluorescent devices. Towards this goal, the donor–acceptor strategy of molecular design has been proven to be an effective approach to obtain high electroluminescence (EL) efficiency. In this context, herein, we report two benzothiadiazole (BTD)-based donor–acceptor π-conjugated fluorescent molecules, 1 and 2, which exhibited an external quantum efficiency (EQE) as high as 7.0% and 8.1%, respectively, in solution-processed doped green OLED devices. The observed high photoluminescence (PL) quantum yield of 81% for 1 and 85% for 2 corroborate the high EUE values of 43% and 48%, respectively, exceeding the traditional limit (25%), hence suggest the utilization of triplet excitons. The reported emitters combine two parameters, i.e. high PL efficiency and high EUE, which are of key importance to harvest maximum EL in OLED devices. Based on the photophysical (solvatochromic experiment) and quantum chemical calculations, the impacts of the D–π–A–π–D molecular design on the regulation of the locally excited and charge transfer components were revealed, which explained the observed high EQE (>5%) and EUE (>25%) values for the BTD-based emitters. The development of emitters with a hybrid local and charge transfer state in combination with the ‘hot exciton’ mechanism is an important strategy to produce highly efficient fluorescent-emitter materials. Besides the impressive EL properties of the emitters, the studied compound 1 as a chemosensor showed the selective sensing of metal cation (Fe2+) and anion (I−) together with the staining agent of Hibiscus rosa-sinensis pollen grains.

We have developed an effective ortho C–H functionalization of arylpyridines and detachable N-pyrimidyl indoles by terminal and internal alkynes using a Re(I) catalyst providing an efficient access to various E-selective alkenylation products. The catalytic reaction is compatible with various aliphatic alkynes, aromatic terminal alkynes and internal alkynes, and structurally different nitrogen heterocycles. Deuterium-labeling experiments indicate that significant deuterium scrambling occurs with the directing groups and acetylenic sp C–H bonds before the migratory insertion.

We report three yellow-green to yellow TADF dopants 26DAcBPy, 25DAcBPy and 26DPXZBPy containing dibenzoyl pyridine as the acceptor and dimethylacridine (Ac) and phenoxazine (PXZ) as the donors with short delayed fluorescence lifetimes of 2.3 μs, 1.9 μs, and 1.0 μs, respectively. The crystal structures show that 26DAcBPy and 26DPXZBPy have a U shape conformation and 25DAcBPy a linear chain structure. All three molecules show intramolecular hydrogen bonding between the pyridine nitrogen and the o-hydrogen of a phenyl ring. These conformations appear to be the result of hydrogen bonding, which leads to rigid structures and provides higher photoluminescence quantum yield. Lastly, these molecules show large dihedral angles between the donor group and the spacer phenyl unit leading to a well-separated HOMO and LUMO and small ΔEST values. Combined with the small ΔEST values, and good photoluminescence (PL) quantum yields, the 26DAcBPy-based devices show a maximum efficiency of 23.1% with a mild efficiency roll-off.

Most of the metal-catalyzed C–H activation/annulation reactions were carried out in organic solvents using expensive oxidants such as Cu(II) and Ag(I) salts. Here, we reported a new approach for a highly regioselective synthesis of isoquinolones from N-alkyl benzamides and alkynes using an Rh(III) catalyst and inexpensive oxygen as the sole oxidant in an aqueous medium. In the reaction, water gave the highest product yield among the solvents used. In addition, at the end of the reaction, the isoquinolone product directly precipitated out from the aqueous solution. The methodology can be applied to a gram scale synthesis. This Rh(III)-catalyzed reaction shows interesting meta selectivity with the meta substituted benzamide and shows various regioselectivities with different substituted alkynes. Moreover, the methodology can be applied to the preparation of biologically active compounds having the isoquinolone core.

Various substituted indolizidinium, quinolizinium and pyrido[1,2-a]azepinium salts synthesized from benzaldehydes (or α,β-unsaturated aldehydes) and alkyne-amines catalyzed by rhodium complexes via C-H activation are demonstrated. The reaction was carried out under mild reaction conditions using Cu(BF4)2·6H2O as oxidant and anion source and inexpensive oxygen as a co-oxidant. A reaction mechanism involving imine formation followed by an ortho C-H activation, alkyne insertion and reductive elimination via a 7-membered rhodacycle is proposed. The present method has been successfully applied to the synthesis of a natural product, ficuseptine.

A highly chemo- and stereoselective nickel-catalyzed borylative cyclization of 1,6-enynes with bis(pinacolato)diboron is described. Enynes containing an electron-deficient alkene such as a vinyl ketone provided alkenylboronates while enynes containing a terminal alkene gave homoallylic boronates. A plausible mechanism involving a nickelacyclopentene intermediate is proposed. In addition, the resulted alkenyl- or homoallylic boronates can be transformed to the corresponding ketones and alcohols via oxidation. Application to a palladium-catalyzed cross coupling reaction of alkenylboronates with aromatic halides has been demonstrated as well.

Thermally activated delayed fluorescence (TADF) emitters are attractive for display and lighting applications. Here, a series of highly efficient blue TADF emitters including 3,5-bis((3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)(pyridin-4-yl)methanone (4BPy-mDTC), (3,5-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)(pyridin-3-yl)methanone (3BPy-mDTC), (3,5-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)(pyridin-2-yl)methanone (2BPy-mDTC) and (3,5-bis(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)(phenyl)methanone (BP-mDTC) were designed and synthesized. The molecular structures feature two meta carbazole substituents attached to a benzoylpyridine (BPy) group or to a benzophenone (BP) group. These compounds show high thermal stability (Td = 371–439 °C), blue emissions (458–488 nm), high photoluminescence quantum yields (PLQY) (75–96%) in thin films and very small energy gaps between S1 and T1 (ΔEST) of 0.01–0.05 eV. In addition, they all reveal TADF properties including small ΔEST, two components in the transient PL decays, prompt emission and temperature-dependent delayed emission. The BPy series appears to give much higher photoluminescence quantum yields (PLQY > 92%) than BP-mDTC (75%) plausibly due to the more rigid structure caused by the interaction between pyridine nitrogen and the aromatic C–H bond. Furthermore, 4BPy-mDTC shows a more delayed component compared to 3BPy-mDTC and 2BPy-mDTC. The electroluminescent devices based on 4BPy-mDTC and 2BPy-mDTC as the dopant emitters exhibit sky blue emission with maximum external quantum efficiencies (EQEs) over 28%, and current and power efficiency and maximum luminance up to 67.0 cd A−1, 60.1 lm W−1 and 20 000 cd m−2, respectively. The presence of the pyridine ring and the position of the nitrogen atom in the molecules are critical for the high quantum yield and device efficiency. The PLQY EQE and luminance are dramatically improved by changing the phenyl into a pyridine group in the dopant in these devices.

A novel copper-promoted multiple aza-[4 + 2] cycloaddition reaction of N-methyleneanilines in situ generated from benzylic azide and alkenes afforded quinolinium salts, biquinolinium salts, biquinolines or substituted quinolines depending on the substitution on the phenyl ring of benzylic azide. The reaction of para substituted benzylic azides and 2 equivalents of alkenes afforded the corresponding substituted quinolinium salts, while benzylic azides without a para substituent provided biquinolinium salts. The copper-promoted cycloaddition reaction also allows biquinoline products to be obtained from ortho-substituted benzylic azides. These reactions work well with both terminal and internal alkenes. Unsymmetrical internal alkene reactions proceed with high regioselectivity. The reaction is likely started by Lewis acidic CuII-assisted rearrangement of benzylic azide to N-methyleneaniline, followed by a [4 + 2] cycloaddition with alkene. Detailed mechanistic studies suggest that the biquinoline and biquinolinium salts are likely formed via radical processes.

A novel p-type charge generation material, DPAF, composed of a ferrocene core and a bis(biphenyl)amino group is designed and synthesized for application to tandem OLED devices. This molecular design not only enhances the thermal properties of ferrocene and the hole mobility, but also maintains its electrochemical stability. The red, green, and blue tandem OLEDs all give excellent device performance with low efficiency roll-off by using n-type C60 and p-type DPAFs as charge generation layers.

Correction for ‘Superior upconversion fluorescence dopants for highly efficient deep-blue electroluminescent devices’ by Yi-Hsiang Chen et al., Chem. Sci., 2016, DOI: 10.1039/c6sc00100a.

A thermally activated delayed fluorescent (TADF) material containing two meta carbazolyl groups on the phenyl ring of the benzoyl-4-pyridine moiety was prepared and its luminescence showed a colour change from blue to green by external stimuli. The organic-blue-light-emitting device using this TADF dopant provided a high external quantum efficiency of 18.4%.

Altering the luminescence properties of a material through external factors is an attractive feature that has the potential for various luminescence-related applications. Here, we report the synthesis and luminescence properties of two anthracene-based donor acceptor compounds, N,N-di-p-tolylanthracen-9-amine (TAA) and 10-bromo-N,N-di-p-tolylanthracen-9-amine (TAAB). In the solid state, the bromo-substituted compound TAAB shows reversible visible switching of the emission by external stimuli such as solvent, mechanical grinding and temperature. Single crystal X-ray studies, powder-XRD analysis and theoretical calculations reveal that switchable emission originated from the different stacking modes of TAAB. Furthermore, we have found that the bromo group interaction in the solid state plays a crucial role in this tunable emission. The other anthracene-based compound TAA does not show such switching of the emission by external stimuli. The observed changes in the luminescence of TAAB by external stimuli suggest potential applications in rewritable optical media, sensors, and optoelectronic devices.

A high glass transition temperature (Tg = 220 °C), high triplet energy gap (ET = 2.76 eV) and high electron mobility material bis(m-terphenyl)oxadiazole was readily synthesized. It can serve as a universal electron transporter for blue, green and red phosphorescent OLEDs with excellent efficiencies. The material shows high current density compared to other electron transport materials and exhibits reduced driving voltage for all color PhOLEDs irrespective of the energy level of the host materials, due to efficient electron injection from 2,5-di([1,1′:3′,1″-terphenyl]-5′-yl)-1,3,4-oxadiazole (TPOTP) to the host material. For the green PhOLED, maximum external quantum efficiency (EQE) over 25%, current efficiency of 97.6 cd A−1 and power efficiency of 100.6 lm W−1 were achieved. The red and blue devices using TPOTP as the electron transporter also show EQE higher than 23% with very low roll-off in efficiencies in practical brightness level.

In this study, we determined that the film morphologies, crystallinities, and optical properties of CH3NH3PbI3−xClx perovskite (PVSK) layers can be manipulated by incorporating a small amount of ethylammonium iodide (EAI) into the perovskite precursor solution. For our EAI-derived films, we observed higher absorbances at higher wavelengths and higher degrees of crystallinity, both of which were associated with the higher surface coverage of the PVSK films. The optimized power conversion efficiency (PCE) improved from 9.4 ± 0.76 to 10.2 ± 0.58% after the addition of 0.5 vol% of EAI. Devices based on EAI-containing PVSK exhibited extremely high stability, retaining approximately 80% of their PCEs (T80) under accelerated heating (65 °C) in a dark N2-filled glove box for over 360 h. In contrast, the corresponding normal device was relatively sensitive to this temperature, with a T80 value of only 45 h. The improved device performance (PCE, stability) arose as a result of the presence of EAI suppressing the crystallization of CH3NH3PbI3−xClx.

A novel copper promoted synthesis of substituted quinolines from various benzylic azides and internal alkynes has been demonstrated. The reaction features a broad substrate scope, high product yields and excellent regioselectivity. In contrast to the known two-step process of acid promoted [4 + 2] cycloaddition reaction and oxidation, the present methodology allows the synthesis of quinolines in a single step under neutral reaction conditions and can be applied to the synthesis of biologically active 6-chloro-2,3-dimethyl-4-phenylquinoline (antiparasitic agent) and 3,4-diphenylquinolin-2(1H)-one (p38αMAP kinase inhibitor). A plausible reaction mechanism involves rearrangement of benzylic azide to N-arylimine (Schmidt reaction) followed by intermolecular [4 + 2] cycloaddition with internal alkynes.

A new strategy for the synthesis of highly substituted benzofurans from meta-substituted hydroxybenzenes and alkynes via a rhodium(III)-catalyzed activation of a sterically hindered C-H bond is demonstrated. A possible mechanism involving dual directing group assisted ortho C-H bond activation is proposed.

An efficient method for the synthesis of functionalized vinyl arenes from the reaction of N-methoxybenzamides or N-phenoxyacetamides with vinylstannanes via rhodium(iii)-catalyzed C–H activation is described. The application of the methodology for the synthesis of a natural product thalactamine and a 7-membered ring oxepine are also demonstrated.

An efficient synthesis of highly substituted isoquinolinium salts from ketimines and alkynes via a Rh(iii)-catalyzed C–H bond activation and annulation reaction is described.

We have synthesized three triptycene derivatives, TCTP (2,6,14-triscarbazolyltriptycene), TATP (2,6,14-tris-(diphenylamino)triptycene) and TPOTP (2,6,14-tris(diphenylphosphoryl)triptycene) which show very high triplet energy gaps (2.94–3.15 eV) and glass transition temperatures (Tgs) ≧ 170 °C. The HOMO and LUMO levels of these three materials indicate that TCTP and TATP possess hole transport characteristics, while TPOTP has electron transport characteristics. These carrier-transporting properties are further supported by the current density–voltage characteristics of the hole-only and electron-only devices of the materials. TATP could be employed as a general host for blue, green and red electrophosphorescence devices providing high brightness, and good current and power efficiencies. The devices using TCTP and TPOTP as the host for the phosphorescence emitter FIrpic showed maximum external quantum efficiencies as high as 10.1% and 16.9%, respectively. By using a blend of TCTP and TPOTP as blue co-host for FIrpic (iridium(III) bis(4,6-difluorophenylpyridinato)picolinate), the device shows an external quantum efficiency of 15.5% at 4.5 V, current efficiency (ηc) of 31.9 cd A−1 at 4.5 V, power efficiency (ηp) of 25.1 lm/W at 4.0 V, respectively. The co-host system greatly improves the performance of the device at normal operation brightness due to the decrease of driving voltage and the balance of hole and electron transport in the device.

Efficient thermally activated delayed fluorescence was observed from a spiro-anthracenone derivative (ACRSA). An organic light-emitting diode containing ACRSA exhibited blue-greenish electroluminescence with a maximum external quantum efficiency of 16.5%.

Highly efficient deep-blue electroluminescent devices are realized via an efficient triplet–triplet annihilation process of styrylpyrene-based emitters., In this study, we revealed a new approach for the development of new triplet–triplet annihilation (TTA) materials with highly efficient deep-blue fluorescence via the incorporation of a styrylpyrene core and an electron-donating group. The resulting deep-blue emitters (PCzSP, DFASP, and DPASP) exhibit intramolecular charge transfer emissions with remarkably high emission quantum yields. The electroluminescent devices based on these three fluorophores as dopants using CBP as a host exhibit very high device efficiencies; in particular, the DPASP-doped device reveals an extremely high EQE of 12%, reaching the limit of a TTA-based device. The EL characteristics of DPASP-doped CBP-based devices at various doping concentrations (0–5%) suggest that the dopant DPASP is responsible for the TTA-type delayed fluorescence in the device; no delayed fluorescence was observed for the device using CBP as the host emitter. Moreover, when using DMPPP with ambipolar characteristics as the host, the deep-blue DPASP-doped device also gives outstanding performance with an EQE of nearly 11% with an extremely small efficiency roll-off, which was ascribed to the excellent charge balance in the emitting layer of the EL device. The TTA process of the SP-based dopants accounts significantly for the superior efficiencies of the EL devices.

Oxabenzonorbornadiene (1a) reacted with various alkynes in the presence of Ni(PPh3)2Cl2, PPh3 and zinc powder in toluene to give two common products 2a and 2b regardless of the alkyne used. The formation of 2a and 2b are proposed to be from the Diels–Alder reaction of 1a and isobenzofuran. The latter is generated from the retro Diels–Alder reaction of [2 + 2 + 2] cycloadducts of 1a and alkynes catalyzed by the nickel system. A series of nickel-catalyzed [2 + 2 + 2] cycloadducts (4a–j and 5a–d) of oxa- and azabenzonorbornadienes (1a–d) with terminal alkynes were isolated at temperatures −5–18 °C. Similarly, hepta-1,6-diyne and octa-1,7-diyne reacted with 1a and 1d to give novel pentacyclic [2 + 2 + 2] cycloadducts 6a–d in 62–75% yields. These products are convenient isobenzofuran and isoindole precursors that react with various dienophiles to afford the corresponding Diels–Alder adducts. In addition, the [2 + 2 + 2] cycloadducts may be used as precursors for the synthesis of aromatic compounds. For example, the reaction of 1a with methyl but-2-ynoate catalyzed by the nickel system provided aromatic compound 3 in 94% yield. In this reaction, 1a is a ‘masked acetylene’ providing an acetylene moiety to 3.

A new method for the synthesis of highly substituted allyl azides by carboazidation of allenes catalyzed by palladium complexes is described. Treatment of 1,1-dimethylallene (1a) with an aromatic iodide ArI 2 (4-CH3COC6H4I, 4-CH3OC6H4I, 3-CH3OC6H4I, 4-CH3C6H4I, 3-CH3C6H4I, 3-C2H5OCOC6H4I, 4-C2H5OCOC6H4I, 4-ClC6H4I, 3-BrC6H4I or 1-iodothiophene), (CH3)3SiN3 and KOAc in the presence of Pd(dba)2 (dba = dibenzylideneacetone) in DMF at 70 °C gave two regioisomers (CH3)2CC(Ar)CH2N33 and (CH3)2(N3)CC(Ar)CH24 in good to excellent yields. The observed regio- and stereoisomer ratios of the allyl azides from these reactions are close to the equilibrium ratio of these isomers at ambient temperature due to a rapid 1,3-shift of the azido group. Reduction of a mixture of 3a and 4a (80∶20, Ar = 4-C6H4COMe) by PPh3–H2O afforded only the sterically less hindered (CH3)2CC(Ar)CH2NH2 in 95% yield further supporting a rapid 1,3-azide shift of 3a and 4a. Mono-substituted allenes RCHCCH2 also undergo carboazidation with aryl iodides and (CH3)3SiN3 in good to excellent yields. For n-butyl-, cyclopentyl- and cyclohexylallene (1b–d), carboazidation gives three isomers 5, 6 and 7 in ca. 1∶1∶1 ratio. For phenyl- and phenoxyallene (1e and f), the reaction produces two stereoisomers Z- (5) and E-CHRC(Ar)CH2N3 (6), where R = Ph and PhO; the regioisomer RCH(N3)C(Ar)CH2 (7) was not observed. In contrast, carboazidation of tert-butylallene (1g) afforded regioisomer t-BuHC(N3)C(Ar)CH2 as the major product (≈90% yield). Based on known palladium-allene and -allyl chemistry, a mechanism is proposed to account for this palladium-catalyzed three-component assembling reaction.

Oxa- and azabenzonorbornadienes react with alkynes in the presence of nickel complexes to give the corresponding [2+2+2] cycloadducts; these reactions can be applied to the construction of multiple fused rings, the preparation of precursors of isobenzofurans and isoindoles and aromatic compounds.

A series of fluxional intramolecular η2-bound arene complexes, (C7H8Ar)Pdl(PPh3), 1a–1d, and 2 may be isolated from the catalytic reactions of norbornadiene (or norbornene) with aryl iodides in the presence of Zn and PdCl2(PPh3)2(eqn. 1) and their structures have been determined by X-ray crystallography and NMR spectroscopy.

Three new bis(indoloquinoxalinyl) derivatives, BIQF (6,6′-(4,4′-(9H-fluorene-9,9-diyl)bis(4,1-phenylene))bis(6H-indolo[2,3-b]quinoxaline)), BIQTP (9,9′-(1,1′:4′,1′′-terphenyl-4,4′′-diyl)bis(6H-indolo[2,3-b]quinoxaline), and BIQMCz (6,6′-(9-p-tolyl-9H-carbazole-3,6-diyl)bis(6H-indolo[2,3-b]quinoxaline)) linked by the fluorenyl, terphenyl and carbazolyl groups, respectively, were synthesized, characterized and used as the hosts for deep-red phosphorescent organic light-emitting diodes (PhOLEDs). The central linkers provide a way to reach higher molecular weights with little change of the energy gap of the molecules relative to the parent indoloquinoxaline molecule. These materials are bipolar and show high glass transition temperatures ∼200 °C and triplet energy gaps 2.25–2.37 eV. The electroluminescent (EL) devices based on these host materials and iridium deep-red emitters exhibit very high device efficiency with a EQEmax mostly above 20%. For example, the device utilizing (tmq)2Ir(acac) as the dopant and BIQMCz as the host shows a maximum current efficiency of 32.4 cd A−1 and a maximum power efficiency of 30.9 lm W−1. The operational lifetimes (T50) of these devices were also measured. The results show that the BIQMCz/Ir(piq)3-based device gave T50 of more than 20000 h at an initial luminance of 500 cd m−2 with a current efficiency (CE) of 23.2 cd A−1 and Commission Internationale de l'Eclairage (CIE) coordinates of (0.67, 0.33).

Reaction of oxabicyclic alkenes with alkynes and organoboronic acids in the presence of Ni(cod)(2), P(t-Bu)(3), and CsF in a binary solvent toluene-methanol (1 : 3) at 75 to 85 °C provided exo-5,6-disubstituted 7-oxanorbornene derivatives in good to excellent yields.

2-Aminoaryl methyl ketones undergo intramolecular oxidative C-H amination to give the corresponding substituted isatins under an oxygen atmosphere in the presence of [CuI(bpy)]2.

The CoI2(PPh3)2/Zn system effectively catalyzes the [2 + 2 + 2] ene-diyne cycloaddition of 1,6-heptadiynes with allenes in a highly regio- and chemoselective fashion to yield substituted benzene derivatives in good to excellent yields.

Two m-terphenyloxadiazole-based electron transporting materials, bis(2-tert-butyl-1,3,4-oxadiazole-5-diyl)-3,3′-m-terphenyl (tOXD-mTP) and bis(2-(4-tert-butylphenyl)-1,3,4-oxadiazole-5-diyl)-3,3′-m-terphenyl (tpOXD-mTP) were synthesized and characterized. These two molecules contained two oxadiazolyl groups and a m-terphenyl linkage as the core structure achieving high triplet energy gaps (ET) of 2.83 and 2.90 eV, respectively. The application of tOXD-mTP and tpOXD-mTP as the electron transporting materials (ETM) in bis(4′,6′-difluorophenylpyridinato)-iridium(III) picolinate (FIrpic)-based blue phosphorescent light-emitting devices effectively confines the triplet exciton in the emitting layers. One of the electroluminescent (EL) devices using FIrpic as the dopant showed an excellent current efficiency of 43.3 cd A−1 and an external quantum efficiency (EQE) of 23.0% with CIE (Commission International de l'Eclairage) coordinates of (0.13, 0.29). The bis(4′,6′-difluorophenylpyridinato)-iridium(III) tetra(1-pyrazolyl)borate (FIr6)-based deeper blue EL device exhibited a high current efficiency of 42.5 cd A−1 and external quantum efficiency of 25.0% with CIE coordinates of (0.14, 0.23). These two tOXD-mTP and tpOXD-mTP based devices show device efficiencies two to three times higher than that based on the well-known electron transporting material 1,3-bis[(4-tertbutylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-7).

An efficient synthesis of fluorenones from diaryl ketones by Pd-catalyzed oxidative cyclization is described. A possible mechanism involving a carbonyl group assisted ortho-C-H activation and cyclometalation followed by a second C-H activation to form a six-membered palladacycle and reductive elimination is proposed.

The addition reaction of silylstannanes with allenes in the presence of Pd2(dba)3·dba in toluene affords (E)-alkenylsilanes having an allylstannane moiety exclusively in good to excellent yields.

Carbocylization of o-halophenyl ketones with propiolates in the presence of Ni(dppe)Br2 and Zn powder in acetonitrile at 80 °C afforded the corresponding 2,3-disubstituted indenols.

A cobalt-catalyzed addition of aryl- and alkenylboronic acids to aldehydes and phthalaldehyde to give the corresponding biarylketones and 3-aryl phthalides in good to excellent yields in one pot is described.

Fluorescent 2,3,6,7,9,10-hexaphenylanthracene-based derivatives (HPhAn) were synthesized to serve as deep-blue dopants in organic electroluminescent (EL) devices. The fluorescent emissions of HPhAn fluorophores, fine-tuned from 462 to 449 nm with varied fluorinated phenyl rings attached to the central carbons of the anthracene core, produced photoluminescence quantum yields of 82–88% in the solid state. Unlike the known monostyrylamine deep-blue dopant, these blue dopants in dilute solutions showed no pronounced spectral red shift with increasing solvent polarity; the emission color of HPhAn dopants is thus insensitive to the polarity of the medium. The highest-occupied molecular orbital (HOMO) and lowest-unoccupied molecular orbital (LUMO) energy levels calculated from the oxidation potentials and optical energy gaps are 5.61–5.70 eV and 2.73–2.89 eV, respectively. These thermally robust compounds undergo thermal decomposition at temperatures greater than 300 °C. The relationships among current density, voltage and luminance, the EL efficiency and the operational stability of devices based on the blue HPhAn dopants were examined. These HPhAn-doped EL devices are activated at voltages less than 3.5 V and attained an external quantum efficiency as much as 5.3% in the deep-blue light region with Commission Internationale d'Eclairage (CIE) coordinates (0.14, 0.10), near the National Television System Committee (NTSC) standard blue coordinates (0.14, 0.08).

The three-component coupling of benzynes with terminal alkynes and activated alkenes in the presence of CuI, PCy(3) and CsF in a 1:1 mixture of CH(3)CN and THF at 50 degrees C for 5 h gave 1-alkyl-2-alkynylbenzenes in good to moderate yields.

Benzynes react with allylic acetates or halides and terminal alkynes in the presence of Pd(PPh3)4, CuI and CsF in CH3CN at 50 degrees C for 5 h to give 1-allyl-2-alkynylbenzene derivatives in good to excellent yields.

o-Dihaloarenes acting as aryne precursors react with acetylenes and nitriles catalyzed by the NiBr(2)(dppe)/dppe/Zn system to give substituted naphthalene, phenanthridine or triphenylene derivatives depending on the reaction conditions in moderate to excellent yields with good tolerance of functional groups.

The feature article surveys the transition metal-catalyzed three-component coupling of allenes and the related allylation reactions. Most of the reactions shown in the article mechanistically proceed via oxidative addition of organic electrophiles to metals, followed by carbometallation of allene and then transmetalation by main group metals or reagents and organometallic reagents. These reactions provide an efficient route for the synthesis of various substituted allyl and vinyl metal reagents and complex organic molecules in highly regio-, stereo- and chemoselective manner in one pot. The metal reagents or pi-allyl-metal intermediates obtained from the reaction are utilized for the allylation of aldehydes, ketones and imines, producing various homoallylic alcohols and amines in a highly regio- and stereoselective manner.

Various N-heteroaromatic compounds, including pyridines, quinolines and isoquinoline, react with arynes and nitrile-containing solvents to give N-arylated 1,2-dihydro-2-pyridinyl, -2-quinolinyl and -1-isoquinolinyl nitriles in excellent yields.

An efficient method for the synthesis of benzolactones and benzolactams via a cobalt-catalyzed [2 + 2 + 2] cocyclotrimerization of alkynyl alcohols and alkynyl amines with propiolates is described.

The NiBr2(dppe)-Zn system effectively catalyzes the [2 + 2 + 2] cocyclotrimerization of arynes with diynes, leading to substituted naphthalene derivatives in moderate to good yields. This cocyclotrimerization reaction shows excellent tolerance of functional groups and leads to products of 5- to 7-membered fused-ring sizes.

We have synthesized two highly efficient phosphorescent iridium metal complexes, Ir(DPQ)2(acac) and Ir(FPQ)2(acac), which are based on cyclometalated quinoline ligands, and discuss details of their electrochemical behavior and photophysical properties (viz. absorption and photoluminescence). Single-crystal X-ray diffraction studies of Ir(DPQ)2(acac) reveal a distorted octahedral geometry, in which the quinoline N atoms and the C atoms of the orthometalated phenyl groups are located at mutual trans and cis positions, respectively. In contrast, Ir(FPQ)2(acac) is an amorphous solid and undergoes a glass transition at 92 °C, which we attribute to the presence of the long di-n-octyl chains in the fluorenyl groups. The phosphorescence of these Ir complexes originates from the dominant 3MLCT excited state shifts to red that occur upon introducing a phenyl substituent and/or a large conjugating aromatic ring into the ligand. A polymer light-emitting diode (PLED) device that uses Ir(FPQ)2(acac) as a phosphorescent dopant and a PVK/PBD blend as the host material produces very high efficiency (an external quantum efficiency of 8.16% at 100 mA cm−2) and a pure-red emission with 1931 CIE (Commission Internationale de L'Eclairage) chromaticity coordinates of (x = 0.68, y = 0.32).

The photochemical reaction of [60]fullerene with RNMe2(R = Ph and Me) gives an adduct (1, R = Ph; 2, R = Me) formed by the addition of an α-C–H bond of the amine to a 6/6 ring junction of [60]fullerene; 2 on further irradiation in the presence of [60]fullerene is converted to the pyrrloidine derivative 3 and 1,2-H2C60.

The NiBr(2)(dppe)-Zn system effectively catalyzes the [2+2+2] cocyclotrimerization of arynes with allenes, leading to 10-methylene-9,10-dihydrophenanthrenes in moderate to good yields. The cocyclotrimerization is highly selective with only the internal double bond of the allenes being involved in the reaction.

Palladium complexes effectively catalyze the three-component assembly of allenes, aryl iodides and stannylgermane in a highly regio-, stereo- and chemoselective fashion to yield (Z)-allylgermanes in good to excellent yields.

[Col2(PPh3)n]–zinc systems (n=1 or 2) exhibit high catalytic activity for the homo-Diels–Alder [2 + 2 + 2] cycloadditions of norbornadiene with various alkynes including terminal and internal acetylenes and methyl prop-2-ynyl ether to give the corresponding deltacyclenes in good to excellent yields.

Treatment of RCH2CCCOX with [60]fullerene in the presence of tricyclohexylphosphine (PCy3) afforded a [2 + 2] cycloaddition product (1: R = H, X = OMe); 2: R = Bu, X = OMe; 3: R = X = Me which resulted from addition of the β, γ-carbons of RCH2CCCOX to the carbon-carbon double bond across a 6/6 ring junction of [60]fullerene.