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Described herein is a convenient and highly regioselective synthesis of substituted isoquinoline derivatives from various aromatic ketoximes and alkynes via a one-pot, rhodium-catalyzed C-H bond activation. In addition, tetrahydroquinoline derivatives are formed in good yields from 2-arylidene-1-cyclohexanone oximes possessing an exocyclic double bond and from tetrahydroxanthone oximes. A possible mechanism is proposed that involves chelation-assisted C-H activation via oxidative addition of Rh(I) to an ortho-C-H bond, insertion of the alkyne, reductive elimination, intramolecular electrocyclization, and aromatization. This mechanism is supported by isolation of the ortho-alkenylation products 7p and 7q. Also described herein is an example of an iridium-catalyzed activation of an sp(3) C-H bond.

A phosphorescent iridium(III) complex Ir(PBQ) 2 (acac) (PBQ: 4-phenylbenzoquinoline, acac: acetylacetone) was designed and synthesized, and the single crystal of this complex was obtained. This complex shows well optoelectronic properties. The organic light emitting devices (OLEDs) based on this complex were successfully fabricated with the device configuration of ITO/NPB or TCTA (40 nm)/Ir-complex: CBP (7%, 30 nm)/BCP (15 nm)/Alq (30 nm)/LiF (1 nm)/Al (100 nm). Using TCTA as the hole-transporting material, the device gives an extremely high external quantum efficiency of 14.6% at 5.0 V, a brightness of 61,693 cd/m 2 at 16.0 V, and a power efficiency of 37.0 lm/W at 3.5 V.

Two phosphorescent complexes Ir(FFBI)2(pmp) and Ir(FFBI)2(pti) based on cyclometalated ligand 1-(4-fluorobenzyl)-2-(4-fluorophenyl)-1H-benzo[d]imidazole (FFBI) and ancillary ligands 2-(phenyliminomethyl)phenol (pmp) or 3-(pyridin-2-yl)-4,5,6,7-tetrahydro-2H-indazole (pti) were synthesized. The single crystal of Ir(FFBI)2(pmp) was obtained. The light emitting and electrochemical properties of these complexes were studied. The electroluminescent devices based on these two complexes with the structure of ITO/NPB (40 nm)/Ir complex: CBP (30 nm)/BCP (15 nm)/Alq (30 nm)/LiF (1 nm)/Al (100 nm) emitted cyan color, with high brightness and efficiencies. The maximum external quantum efficiencies reached to 6.8% and 11.6%, respectively.

In this paper, we developed a series of novel arylamino-containing spiro triplet state host materials for green and blue phosphorescent emitters. With high enough energy gap and compatible HOMO, LUMO levels, we demonstrated the green PHOLED with a low driving voltage of 2.5 V and a high power efficiency of 38.5 lm/W. We also demonstrated blue PHOLED with a very low driving voltage of 3.0 V and a current efficiency of 9.2 cd/A.

The film amorphism of 2,2′-bistriphenylenyl (BTP), a blue-light emitter with all sp2-hybridized polyaromatic, is enhanced by incorporating phenyl groups between the two triphenylene (TP) planes. This series of compounds are BTP, 1,4-di(triphenylen-2-yl)benzene (T1), and 4,4′-di(triphenylen-2-yl)biphenyl (T2), where the latter preserve the characteristics of all sp2 hydrocarbons and improve the optimized electroluminescence (EL) performance. Specifically, the most efficient T2-based device can reach a maximum external quantum efficiency of 5.2% and a very high luminescence of 47776 cd/m2 in the deep-blue region with Commission Internationale d’Enclairage (CIE) coordinates of (0.15, 0.12). The efficiency approaches the upper theoretical limit of 5−5.5%, estimated for a singlet emitter with a refractive index of 1.7−1.5. For comparison, the optimized BTP-based devices confer the corresponding values of 4.2%, 21 204 cd/m2, and (0.14, 0.11). Such an improvement is ascribed to the effect of introducing the phen...

Two phosphorescent iridium(III) complexes Ir(DFPP)2(acac) and Ir(DFPP)2(pic) (DFPP, 2-(2,4-difluorodephenyl)-3-phenylpyridine; acac, acetylacetone; pic, 2-picolinic acid) were synthesized. The complexes have strong phosphorescent characters. The organic light emitting devices (OLEDs) based on these complexes with the configuration of ITO/NPB (40 nm)/Ir complex: CBP (7%, 30 nm)/BCP (15 nm)/Alq (30 nm)/LiF (1 nm)/Al (100 nm) were fabricated. The device based on Ir(DFPP)2(acac) emits green color with a maximum external quantum efficiency of 4.14%, a brightness of 28,786 cd m−2; and the device based on Ir(DFPP)2(pic) emits cyan color with a maximum external quantum efficiency of 3.05%, a brightness of 24,220 cd m−2.

Two red emitting iridium complexes (DBA) 2 Ir(acac) and (BA) 2 Ir(acac) (DBA = 5,6-dihydro-benzo[c]acridine, BA = benzo[c]acridine, acac = acetylacetone) were synthesized. Organic light-emitting devices using these complexes as dopant emitters have been fabricated. The results showed that these complexes have strong phosphorescent characters and the devices emit pure red light. The maximum brightness of the device based on (DBA) 2 Ir(acac) is 9540 cd/m 2 with an external quantum efficiency of 4.66%.

We have synthesized a new blue-emitting iridium complex, FIrpytz (iridium(III) bis(4,6-difluorophenylpyridinato)-4-(pyridin-2-yl)-1,2,3-triazolate), and two new bis(triphenylsilyl) derivatives, BSB (4,4'-bis-triphenylsilanyl-biphenyl) and BST (4,4"-bis(triphenylsilanyl)-(1,1',4',1")-terphenyl) as hosts for blue phosphorescence devices. The photoluminescence (PL) and electroluminescence (EL) properties of different host/dopant combinations were studied in details. These two arylsilanes showed glass transition temperatures (T g s)≥100°C higher than those of UGH1 (diphenyl-di(o-tolyl)silane) and UGH2 (1,4-bis(triphenylsilyl)benzene), the common arylsilane-based hosts. The band gaps for BSB and BST are 4.16 and 3.78 eV, respectively, lower than that of UGH2 of 4.40 eV. The FIrpytz-doped UGH2, BSB and BST films exhibit PL quantum yields of 0.58, 0.83 and 0.48, respectively. The EL devices using FIrpytz or FIrpic (iridium(III) bis(4,6-difluorophenylpyridinato)-picolinate) as the blue phosphorescence dopants and UGH2, BSB and BST as the hosts also showed that BSB-based devices gave the best device efficiencies. Both PL and EL studies show that BSB is better than UGH2 and BST as the host material for FIrpytz and FIrpic. In particular, the use of FIrpytz as dopant, BSB as host and LiF/Al as cathode provides a remarkably efficient combination for blue electrophosphorescence device reaching a very high external quantum efficiency of 19.3% at 8.5 V and a high luminance level of 20500 cd m -2 at 19.3 V after electroluminescence started at 5.1 V.

Atomic force microscopy (AFM) is employed to unveil the film morphology of 2,2‘-bistriphenylenyl (BTP), an all sp2-hybridized polyaromatic blue emitter derived from two triphenylenes (TP) in the OLED layout (organic light-emitting diode). It is generally believed that molecules with such planar cores require derivatization or steric hindrance to hamper intermolecular π−π stacking and reduce self-absorption. X-ray crystallographic results of BTP crystals show that the two triphenylenyls are coplanar, indicative of a likely tendency toward self-quenching. Surprisingly, AFM reveals grainy nanoaggregates of the BTP layer in the device, yet BTP films exhibit excellent performance for OLED applications. To correlate luminescent spectra with the molecular structure, BTP films of crystalline, nanoaggregated, and amorphous features are prepared and subjected to spectroscopic studies. These AFM and spectroscopic results in conjunction with simulation results of a small torsion barrier to rotate the TP rings suggest...

Three blue-light emitting dipyrenylbenzene derivatives, 1-(4-(1-pyrenyl)phenyl)pyrene (PPP), 1-(2,5-dimethoxy-4-(1-pyrenyl)phenyl)pyrene (DOPPP), and 1-(2,5-dimethyl-4-(1-pyrenyl)phenyl)pyrene (DMPPP), have been prepared by the Suzuki coupling reaction of aryl dibromides with pyreneboronic acid in high yields. These compounds exhibit high glass-transition temperatures of 97–137 °C and good film-forming ability. As revealed from single-crystal X-ray analysis, these dipyrenylbenzenes adopt a twisted conformation with inter-ring torsion angles of 44.5°–63.2° in the solid state. The twisted structure is responsible for the low degree of aggregation in the thin films that leads to fluorescence emission of the neat films at 446–463 nm, which is shorter than that of the typical pyrene excimer emission. The low degree of aggregation is also conducive for the observed high fluorescence quantum yields of 63–75%. In organic light-emitting diode (OLED) applications, these dipyrenylbenzenes can be used as either the charge transporter or host emitter. The non-doped blue OLEDs that employ these compounds as the emissive layer can achieve a very high external quantum efficiency (ηext) of 4.3–5.2%. In particular, the most efficient DMPPP-based device can reach a maximum ηext of 5.2% and a very high luminescence of 40 400 cd m–2 in the deep-blue region with Commission Internationale d'Enclairage (CIE) coordinates of (0.15, 0.11).

Cobalt complex/Zn systems effectively catalyze the reductive coupling of activated alkenes with alkynes in the presence of water to give substituted alkenes with very high regio- and stereoselectivity in excellent yields. While the intermolecular reaction of acrylates, acrylonitriles, and vinyl sulfones with alkynes takes place in the presence of CoI2(PPh3)2/Zn, the reaction of enones and enals with alkynes requires the use of the CoI2(dppe)/Zn/ZnI2 system. The intramolecular reductive coupling of activated alkenes (enones, enals, acrylates, and acrylonitriles) with alkynes also works efficiently. Further a variety of cyclic lactones and lactams were prepared using this methodology. Possible mechanistic pathways are proposed based on a deuterium-labeling experiment carried out in the presence of D2O.

A series of aminobenzanthrone derivatives, possessing a keto and an amino group on the aromatic ring, are synthesized and their photoluminescence (PL) and electroluminescence (EL) properties are studied in detail. These compounds emit strongly in solution and in the solid state, with the emission maxima in the range of 528-668 nm resulting from charge-transfer transitions from the amino group to the keto moiety. The emission wavelength depends greatly on the polarity of the solvent. A red shift of nearly 100 nm is observed from n-hexane to dichloromethane for each of these compounds. The PL quantum yields of these molecules also depend tremendously on the solvent. The values are between 88 and 70 % in n-hexane and decrease as the polarity of the solvent increases. The single-crystal X-ray diffraction data reveal that the aminobenzanthrone planes of these molecules stack in the crystals in an antiparallel head-to-tail fashion. This strong dipole-dipole interaction accounts for the observed red-shifted emissions of the aminobenzanthrone molecules in powders and in films relative to those in nonpolar solvents. Electroluminescent devices using aminobenzanthrone derivatives as the host emitters or dopants emit orange to red light in the range 590-645 nm. High brightness, current efficiency, and power efficiency are observed for some of these devices. For example, the device using N-(4-t-butylphenyl)-N-biphenyl-3-benzanthronylamine as the emitter gives saturated red light with a current efficiency of 1.82 cdA -1 , brightness of 11253 cd m -2 , and Commission Internationale de l'Eclairage (CIE) coordinates of (0.64,0.36); the device using N-(2-naphthyl)-Ν-phenyl-3-benzanthronylamine as the emitter gives orange-red light with a current efficiency of 3.52 cd A -1 , brightness of 25 000 cd m -2 , and CIE coordinates of (0.61,0.38).

A novel method for the regio- and stereoselective synthesis of substituted 3-coumaranones from salicylaldehydes and allenes using a rhodium(III) catalyst has been developed. This procedure gives access to new 2-vinyl-substituted 3-coumaranone compounds. The method involves a RhIII-catalyzed aldehyde C–H activation and annulation reactions. Moreover, this RhIII-catalyzed [4 + 1] annulation reaction has been applied to 2-aminobenzaldehydes to afford 2,2-disubstituted 3-indolinones.

The dual annulation of alkyne (VIII) with isolated aldimine (IX) leads to known bioactive tetracyclic derivative (X).

A one-pot reaction of substituted benzaldehydes with alkyne-amines by a Rh-catalyzed C-H activation and annulation to afford various natural and unnatural protoberberine alkaloids is reported. This reaction provides a convenient route for the generation of a compound library of protoberberine salts, which recently have attracted great attention because of their diverse biological activities. In addition, pyridinium salt derivatives can also be formed in good yields from α,β-unsaturated aldehydes and amino-alkynes. This reaction proceeds with excellent regioselectivity and good functional group compatibility under mild reaction conditions by using O2 as the oxidant.

Cationic N-heterocycles are an important class of organic compounds largely present in natural and bioactive molecules. They are widely used as fluorescent dyes for biological studies, as well as in spectroscopic and microscopic methods. These compounds are key intermediates in many natural and pharmaceutical syntheses. They are also a potential candidate for organic light-emitting diodes (OLEDs). Because of these useful applications, the development of new methods for the synthesis of cationic N-heterocycles has received a lot of attention. In particular, many C-H activation methodologies that realize high step- and atom-economies toward these compounds have been developed. In this review, recent advancements in the synthesis and applications of cationic N-heterocycles through C-H activation reactions are summarized. The new C-H activation reactions described in this review are preferred over their classical analogs.

Four cobalt-catalyzed oxidative annulation reactions of nitrogen-containing arenes with alkynes proceeds by C-H activation, thus leading to biologically useful quaternary ammonium salts, including pyridoisoquinolinium, cinnolinium, isoquinolinium, and quinolizinium salts, in high yields. The results are comparable to those reactions catalyzed by rhodium and ruthenium complexes. The transformation of the salts into various N-heterocycles has also been demonstrated.

Transition-metal-catalyzed C - H activation is considered to be an important tool in organic synthesis and has been accepted and widely used by chemists because it is straightforward, cost-effective, and environmentally friendly. A variety of functional groups have been used to direct metal complexes and achieve regioselective C - H activation. Most directing is achieved through the σ-bond coordination of functional groups to the metal catalyst, followed by ortho-selective C - H bond cleavage. However, recent work has demonstrated that π-coordinating functional groups can also assist in guiding metal complexes for site-selective C - H bond activation. This emerging approach significantly expands the scope of C - H activation reactions in organic synthesis. Herein, recent developments in this field are summarized.

A novel method for the regio- and stereoselective synthesis of substituted 3-coumaranones from salicylaldehydes and allenes using a rhodium(III) catalyst has been developed. This procedure gives access to new 2-vinyl-substituted 3-coumaranone compounds. The method involves a Rh(III)-catalyzed aldehyde C-H activation and annulation reactions. Moreover, this Rh(III)-catalyzed [4 + 1] annulation reaction has been applied to 2-aminobenzaldehydes to afford 2,2-disubstituted 3-indolinones.

The Heck reaction is a well-established transition-metal catalyzed reaction for coupling alkenes with sp2 alkyl halides to give novel unsaturated compounds. Herein we report an analogous Heck-inspired, simple efficient coupling of sp3 alkyl halides with electron-withdrawing alkenes to form reductive coupling products where saturated esters are obtained. A range of acrylates were coupled with sp3 alkyl halides in the presence of Ni(PPh3)2Cl2 catalyst, Zn metal powder, CH3CN solvent, and water, at 80 °C to form the reductive Heck type saturated ester products in good yields. This strategy was further extended to couple oxabenzonorbornadiene with the alkyl halides resulting in ring opening to give rise to bicyclic alcohol products. The mechanism for both the reactions appears to be the usual oxidative-addition driven alkene insertion reaction where the water appears to act as the protonating agent.

Highly substituted pyridinium salts are synthesized via a multicomponent reaction of vinyl ketones/aldehydes, amines, and alkynes.

ConspectusOver the last three decades, transition-metal-catalyzed organic transformations have been shown to be extremely important in organic synthesis. However, most of the successful reactions are associated with noble metals, which are generally toxic, expensive, and less abundant. Therefore, we have focused on catalysis using the abundant first-row transition metals, specifically cobalt. In this Account, we demonstrate the potential of cobalt catalysis in organic synthesis as revealed by our research.We have developed many useful catalytic systems using cobalt complexes. Overall, they can be classified into several broad types of reactions, specifically [2 + 2 + 2] and [2 + 2] cycloadditions; enyne reductive coupling; reductive [3 + 2] cycloaddition of alkynes/allenes with enones; reductive coupling of alkyl iodides with alkenes; addition of organoboronic acids to alkynes, alkenes, or aldehydes; carbocyclization of o-iodoaryl ketones/aldehydes with alkynes/electron-deficient alkenes; coupling of thio...

An efficient o-arylation of pivalamides by aryl iodides via rhodium(III)-catalyzed C–H activation is demonstrated for the first time. Further, the biaryl products can be converted effectively into biologically active phenanthridine and phenanthridinone derivative.

Three m-terphenyl oxadiazole derivatives, 3,3″-bis(5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl)-1,1':3',1″-terphenyl (4PyOXD), 3,3″-bis(5-(pyridin-3-yl)-1,3,4-oxadiazol-2-yl)-1,1':3',1″-terphenyl (3PyOXD), and 3,3″-bis(5-phenyl-1,3,4-oxadiazol-2-yl)-1,1':3',1″-terphenyl (PhOXD), were synthesized. They exhibit relatively high electron mobilities compared with those of known electron-transport materials such as TAZ, BAlq, and BCP+Alq3. These materials were then utilized as electron transporters and hole/exciton blockers for blue, green, and red phosphorescent organic light-emitting diodes. The devices exhibited reduced driving voltages, very high efficiency, and negligible roll-off. More importantly, among these three oxadiazole derivatives, PhOXD performed as an ideal electron-transporting material for the blue, green, and red devices with excellent external quantum efficiencies (EQEs,26%) as well as current and power efficiencies. Using these materials as an electron-transporting/exciton-blocking layer, low roll-off was achieved for the devices, indicative of excellent confinement of the triplet excitons in the emitting layer even at high current densities. At the normal operation brightness of 1000 cd m(-2), the EQEs remained21.3% for these basic color devices. In addition, the relationships between physical properties and structures of the molecules such as the electron mobility, triplet energy gap, and efficiency can be clearly rationalized.

This efficient reaction which proceeds regioselectively at the sterically more congested C—H bond can be scaled up.

A cobalt-catalyzed dual annulation reaction for the synthesis of variously substituted indenoisoquinolinones from 2-bromobenzaldehydes, amines, and methyl 2-(ethynyl)benzoates has been developed. This method could also be applied to the synthesis of an array of highly functionalized bioactive indenoisoquinolinones and their derivatives. A possible mechanism of the cobalt catalysis is proposed, involving imine formation from bromobenzaldehyde and the amine, followed by a series of oxidative addition, alkyne insertion, cyclization reactions, and carbon–carbon double-bond migration. The regioselective alkyne insertion plays an important role for the success of the second annulation.

Rh-catalyzed reaction of N-hydroxybenzamidines with an excess of internal alkynes and an excess of Cu(OAc)2 as the oxidant is described to produce polyhetarenes in good yields.

A synthetic method for highly substituted pyridinium salts from the multicomponent reaction of vinyl ketones/aldehydes, amines, and alkynes using a rhodium catalyst is demonstrated. The catalytic reaction proceeds via an in situ generated imine-assisted Rh(III)-catalyzed vinylic C-H activation.

The highly chemo- and stereoselective title reaction furnishes functionalized pyrrolidines and dihydrofurans via cobalt-triggered C-H activation.

This paper investigated the blue shift of photoluminescence and the changes of surface morphology of Alq 3 films by ionic argon plasma bombardment. Plasma with different conditions was applied to bombard thin Alq 3 films, modifying both the physical and chemical properties of the films. After characterizing Alq 3 films treated with different RF power by XPS, PL and AFM, we proposed the mechanisms to explain the absence of PL blue shift and chemical shift after the films were exposed in the air for more than 3 h. Experimental results showed that molecular structure damages would affect the bandgap of Alq 3 , leading to the blue shift effect. XPS results also showed that binding energy shifts are caused by enriched oxygen covalent bonds formed inside the films after plasma treatment. Also, surface roughness improves as RF power is increased.

This work reports on the fabrication of an efficient polymer light-emitting device by applying iridium (Ir) complex, dibenzo[ f , h ]-quinoxaline iridium (acetylacetonate) [Ir(DBQ) 2 (acac)], as the phosphorescent dopant, poly(9-vinylcarbazole) as the matrix layer, and 2-(4-biphenylyl)-5-(4- tert -butyl-phenyl)-(1,3,4-oxadiazole) as the electron transport material. The trapping of charge carriers at the Ir(DBQ) 2 (acac) dopant sites dominates the electroluminescence (EL) of the devices. The device emits red electrophosphorescence centered at 610 nm, exclusively from the Ir dopant and an EL efficiency of 8.5 cd/A (1287 cd/m 2 ) biased at 14.5 mA/cm 2 .

[Reaction: see text]. An efficient method for the synthesis of cis-2-alkyl- or allyl-1,2-dihydronaphthalenes via a nickel-catalyzed highly regio- and stereoselective ring-opening addition of alkyl- or allylzirconium reagents to 7-oxabenzonorbornadienes is described. Treatment of 7-oxabenzonorbornadienes 1a-c with various alkylzirconium reagents 2a-j (Cp2ZrClCH2CH2R: R = tert-butyl, n-butyl, n-pentyl, -(CH2)3CH=C(CH3)2, -SiMe3, -CH2SiMe3, -(CH2)3Br, cyclopentyl, cyclohexyl, and benzyl) in the presence of NiBr2(dppe) and Zn powder in dry THF at 50 degrees C afforded the corresponding cis-2-alkyl-1,2-dihydronaphthalene derivatives 3a-m in good yields. In addition, allyl zirconium reagents 4a-c also underwent ring-opening reactions with 1a and 1c to give 5a-d in very good yields. The alkylative ring-opening products from 7-oxabenzonorbornadiene can be further converted to naphthalene derivatives 6a-c, via an acid-mediated dehydration, in good to excellent yields. A possible mechanism for the present catalytic reaction was proposed.

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%.

Several iridium complexes {iridium(III)bis[2-(3-methoxyphenyl)-1,3-benzothiozolato-N,C 2′ ] acetylacetonate (MeO-BT) 2 Ir(acac), iridium(III)bis[2-(2,4-difluorophenyl)-1,3-benzothiozolato-N,C 2′ ] acetylacetonate (2F-BT) 2 Ir(acac), and iridium(III)bis[2-(2,4-difluorophenyl)-6-fluoro-1,3-benzothiozolato-N,C 2′ ] acetylacetonate (3F-BT) 2 Ir(acac)} having different substituents on 2-phenylbenzothiazole have been synthesized. The phosphorescent light emitting diodes (PHOLEDs) using these iridium complexes as dopant emitters were fabricated. The experimental results revealed that the emissive colors of PHOLEDs could be finely tuned by suitable modification of the substituents on the 2-phenylbenzothiazole ligands. Furthermore, these iridium complexes show better emissive properties than the known iridium(III)bis(2-phenylbenzothiozolato-N,C 2′ ) acetylacetonate (BT) 2 Ir(acac).

A highly regio- and stereoselective ring-opening addition of alkenylzirconium reagents to bicyclic olefins catalyzed by nickel complexes was described. Treatment of 7-oxa- and 7-azabenzonorbornadienes (1a-e) with various terminal alkenylzirconium reagents 2a-f (Cp(2)ZrClCH=CHR; R = t-Bu, n-Pr, n-Oct, 1-cyclohexenyl, SiMe(3), and Ph) in the presence of Ni(PPh(3))(2)Cl(2) and Zn powder (or a combination of ZnCl(2) and NEt(3)) in dry THF at 50 degrees C afforded the corresponding cis-2-alkenyl-1,2-dihydronaphthalene derivatives 3a-l in moderate to excellent yields. Under similar reaction conditions, internal alkenylzirconium reagents 2g,h (Cp(2)ZrClCR=CHR: R = Et and n-Pr) also undergo ring-opening addition to oxanorbornadienes 1a and 1d to give cis-2-alkenyl-1,2-dihydronaphthalene derivatives 4a-c in good yields. Possible pathways involving the transfer of alkenyl group in the alkenylzirconium reagent to the Ni(II) center followed by migration of the alkenyl group from the Ni(II) center to the carbon-carbon double bond of 7-oxanorbornadiene or the reaction of 7-oxanorbornadiene with Ni(0) to form a Ni(II)-pi-allyl prior to the transfer of the alkenyl group as key steps for the catalytic reaction were proposed and discussed.

In the presence of CoX 2 (PPh 3 ) 2 /3 PPh 3 and zinc metal conjugated alkenes (CH 2 CHCOOR, CH 2 CHCN, CH 2 CHSO 2 Ph and CH 2 CHCONEt 2 ) undergo reductive tail-to-tail dimerization to yield the corresponding saturated linear products. Under similar reaction conditions, vinylarenes (ArCHCH 2 ) give stereoselective head-to-tail dimerization products, trans -1,3-diarylbut-1-ene, in good to excellent yields.

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.