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The electrophilic halogenation of arenes is perhaps the simplest method to prepare aryl halides, which are important structural motifs in agrochemicals, materials, and pharmaceuticals. However, the nucleophilicity of arenes is weakened by the electron-withdrawing substituents, whose electrophilic halogenation reactions usually require harsh conditions and lead to limited substrate scopes and applications. Therefore, the halogenation of arenes containing electron-withdrawing groups (EWGs) and complex bioactive compounds under mild conditions has been a long-standing challenge. Herein, we describe Brønsted acid-catalyzed halogenation of arenes with electron-withdrawing substituents under mild conditions, providing an efficient protocol for aryl halides. The hydrogen bonding of Brønsted acid with the protic solvent 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) enables this transformation and thus solves this long-standing problem.

Organic light-emitting diodes (OLEDs) have become the predominant technology in display applications because of their superior light weight, flexibility, power conservation, and environmental friendliness, among other reasons. The device’s performance is determined by the intrinsic properties of organic emitters. The aggregation structure of emitters, in particular, is crucial for color purity and efficiency. Intra- and intermolecular interactions, such as hydrogen bonds (H-bonds), can reduce structural vibrations and torsions, which affect the stability of emitting layer films and optoelectronic properties of emitting materials. Hence, by regulating the H-bond interaction, the desired properties could be obtained. This mini-review focuses on the influence of intra- and intermolecular H-bond interactions on the optoelectronic properties of high-performance emitters.

The fabrication of deep-blue emitting materials with high color purity is crucial for the realization of ultra-high-definition display technology based on organic light-emitting diodes (UHD-OLEDs). However, the intrinsic broad-band emission of organic emitters makes this task difficult. In this study, 9,9-dimethyl-9,10-dihydroacridine (DMAC) was fused with an additional phenyl moiety to design rigid 12,12-dimethyl-7,12-dihydrobenzo[a]acridine (DMBA) as a novel chromophore for design of deep-blue narrow-band emission emitters. Furthermore, functionalization of DMBA with a cyano group yielded two bipolar emitters, viz. 12,12-dimethyl-7-phenyl-7,12-dihydrobenzo[a]acridine-3-carbonitrile (BACN) and 4-(12,12-dimethyl-7-phenyl-7,12-dihydrobenzo[a]acridin-3-yl)benzonitrile (BAPCN). The single-crystal structure analysis confirmed that BACN and BAPCN featured large rigid planar structures. The photophysical study demonstrated that both emitters exhibited narrow-band emissions in the deep-blue region with high fluorescence quantum efficiencies. The doped device based on BACN demonstrates an efficient deep-blue emission that peaks at 437 nm with a small full width at half maximum of 41 nm/0.26 eV and a corresponding Commission International de L’Eclairage (CIE) coordinate of (0.153, 0.049). Meanwhile, their non-doped devices show lower turn-on voltage and smaller external quantum efficiency (EQE) roll-off, particularly in the BAPCN-based non-doped device with a negligible EQE roll-off of only 4.4% at 10000 cd m-2, as a consequence of their good/balanced carrier transporting properties. The optoelectronic properties of these emitters substantiate their potential as deep-blue emitting materials for OLED applications.

Molecular oxygen as a green, non-toxic and inexpensive oxidant has displayed lots of advantages compared with other oxidants towards more selective, sustainable, and environmentally benign organic transformations. The oxygenation reactions which employ molecular oxygen or ambient air as both an oxidant and an oxygen source provide an efficient route to the synthesis of oxygen-containing compounds, and have been demonstrated in practical applications such as pharmaceutical synthesis and late-stage functionalization of complex molecules. This review article introduces the recent advances of radical processes in molecular oxygen-mediated oxygenation reactions. Reaction scopes, limitations and mechanisms are discussed based on reaction types and catalytic systems. Conclusions and perspectives are also given in the end.

Porous carbon has been expected to be a potential candidate as a lightweight and efficient microwave absorber. Nano-porous carbon carbonized directly from a walnut shell exhibits narrow microwave absorption frequency bandwidth, while the activation process can adjust the pore structure and optimize the microwave absorption performance. Herein, porous carbon materials were successfully prepared using walnut shells as precursors and ZnCl2 as the activating agent. The superior microwave absorption performances of the as-prepared samples could be attributed to the well-developed pore structures and the enhanced dielectric loss capacities of the samples. The interfacial polarization in the walls of the pores and the defects in the samples significantly contributed to the enhancement of the dielectric loss capacities of the samples. In this work, the broadband microwave absorbing porous carbon exhibited an effective absorption bandwidth (reflection loss ≤ −10 dB) of 7.2 GHz (ranging from 10.8 GHz to 18.0 GHz) when the absorber thickness was 2.5 mm. In addition, an effective absorption bandwidth of 6.0 GHz (ranging from 11.4 GHz to 17.4 GHz) could also be achieved when the absorber thickness was only 2.0 mm. The samples exhibited low densities, strong microwave absorption performances and wide effective absorption bandwidths with thin absorber thicknesses, due to which they have a great potential as lightweight and efficient microwave absorbers.

A novel bipolar compound triphenylamine-dibenzothiophene S,S-dioxide (TPAFSO) based on a dibenzothiophene-S,S-dioxide (DBTO) moiety and a triphenylamine (TPA) unit, in which the TPA unit is linked at its 4-position to the DBTO group at its 3,7-position, is designed and synthesized. The experimental results clearly show that TPAFSO exhibits a high photoluminescence efficiency of 0.52 in a film form and good/balanced carrier injecting properties, as well as an adequate triplet energy (ET) of 2.1 eV to sensitize red phosphor. Hence, solution-processable single-layer green OLEDs using TPAFSO as emitters exhibit a maximum luminous efficiency (LE) of 4.7 cd A−1 and a maximum brightness of 5952 cd m−2 with a low turn-on voltage of 2.5 V, which is superior to the performance of double-layer devices. Furthermore, considering the TPAFSO as a solution-processed host for red emitters, 5% bis(2-(2′-benzothienyl)-pyridinato-N,C3′)iridium(acetylacetonate) (Ir(btp)2(acac))-doped single-layer devices give a maximum quantum yield of 3.9% and a saturated red emission with CIE coordinates of (0.68, 0.32), which are much better than that of Ir(btp)2(acac)-doped poly(N-vinylcarbazole)-2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PVK-PBD) single-layer devices. Additionally, the red OLEDs using 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4Hpyran (DCJTB)-doped TPAFSO as the emitting layer exhibit a maximum LE of 1.8 cd A−1, and can be compared to the performances of DCJTB/Alq3-based multilayer devices via an evaporation process.

Efficient deep-blue fluorescence and high color purity (narrow emission) are highly desired characteristics for organic light-emitting diodes (OLEDs). Herein, we report on hydrogen-bond (H-bond)-induced narrow emission based on a donor–acceptor-type molecule TPA-PPI-OH with a hydroxyl (–OH) substituent. Nuclear magnetic resonance (NMR) spectroscopy and single X-ray crystal data indicated the existence of intra- and intermolecular H-bonds interactions in TPA-PPI-OH. These interactions proved beneficial to suppress the structural vibrations and thereby caused a narrower full-width at half-maximum (FWHM) PL emission of TPA-PPI-OH compared to its hydroxy-free counterpart TPA-PPI (57 nm vs. 63 nm in film). The photophysical properties revealed that the lowest excited state (S1) of TPA-PPI-OH is a hybridized local and charge-transfer excited state; thus, TPA-PPI-OH could show high fluorescence efficiencies in various solvents (50% even in acetonitrile). The non-doped deep-blue device based on TPA-PPI-OH exhibited a maximum EQE of 7.37% with a small efficiency roll-off (7.37% @ 100 cd m−2; 5.48% @ 1000 cd m−2) and narrow FWHM of 58 nm (71 nm for TPA-PPI).

Deep-blue light emitting materials are of great significance in the fields of commercial full-color organic light-emitting diodes (OLEDs) and solid-state lighting. The hybridized local and charge-transfer excited state (HLCT) is a promising strategy to achieve deep-blue emission and high photoluminescence quantum yield. Based on HLCT, we designed and synthesized two novel donor–π–acceptor, 9,9-dimethylfluorene-bridged fluorophores (DFPBI & TFPBI) for efficient deep-blue OLED applications. Non-doped devices, with DFPBI and TFPBI as emitters, exhibit deep-blue emission with CIE coordinates of (0.154,0.042) and (0.152,0.054), accompanied by good EL performance with maximum external quantum efficiencies (EQEs) of 4.18% and 5.74%, respectively. In particular, the TFPBI-based non-doped device displays a slow efficiency roll-off at high luminance with an EQE of 5.50% and 4.80% at 100 cd m−2 and 1000 cd m−2, respectively. This work not only demonstrates the potential of these two fluorophores in deep-blue OLEDs, but also provides tactics for the design of deep-blue light emitting materials by using the 9,9-dimethylfluorene-bridged D–π–A architecture.

Oxygenases-catalyzed reductive activation of molecular oxygen and incorporation of O atoms into an organic molecule is undoubtedly one of the most attractive research areas. Typically, these oxygenation reactions proceed with high selectivity and reactivity, which is seldom found in its "biomimetic" chemocatalytic counterparts. Furthermore, enzymatic oxygenation can avoid undesired overoxidation, which is frequently observed in (industrial) chemical transformation. Therefore, it is not surprising that tremendous attention has been paid to enzymatic oxygenation. Their application in organic synthesis has been steadily growing over the years. The goal of the present Review is to provide a handy reference for chemists interested in using homogeneous oxygenase catalysis and those interested in discovering new types of biomimetic oxidations and oxygenations with dioxygen. In this Review, we will review the recent advances in in homogeneous oxygenase catalysis to reveal the great achievements and potentials in this field.

In the present paper, life cycle analysis of coal-based synthetic natural gas (SNG) is performed for heat supply and electricity generation in China with a full consideration of energy efficiency, environmental pollutions and greenhouse gas emissions. Several different technical routes of SNG are studied in detail and the emissions of SO2, NOx, CO2 and energy efficiency are all calculated. For comparisons, technical routes of ultra supercritical and coal-fired power generations are also analyzed together with a direct use of coal for heat supply. Our results show that the cogeneration of heat and electricity is a suitable technical route for SNG utilization. Comparing with ultra-supercritical and coal-fired power generations, technical routes based on SNG could significantly reduce the emissions of pollutants (especially for heat supply) with an acceptable level of the energy efficiency. After synthesis of SNG, our life cycle analysis suggests that SNG should be transported to the energy demand center for further power generation locally.

A series of ferrite/Co/porous carbon materials were prepared by the situ-thermal carbonization of ferrite/ZIF-67 under N 2 atmosphere, and the microwave absorption properties have also been investigated. The magnetoelectric synergistic microwave absorbing material is promising as an efficient microwave absorbing material. The component absorbers with unique porous carbon structure make great contribution to the impedance match, interface polarization, magnetoelectric synergistic effect, and multiple reflection and scattering loss. The carbonization temperature indicates a crucial effect on the porous structure, and too high temperature will result in the collapse of the porous structure. The ferrite/Co/porous carbon fabricated at 500 °C (FC500) exhibits the most enhanced microwave absorbing performance. The maximum reflection loss (RL) of FC500 reaches −31.05 dB at 14.32 GHz, and the effective absorption bandwidth (RL ≤ −10 dB) is 4.8 GHz (12.24 GHz–17.04 GHz) corresponding to a thickness of 1.5 mm. The maximum reflection loss (RL) can reach −47.31 dB at 8.4 GHz, and absorption bandwidth (RL ≤ −10 dB) is 2.72 GHz (6.80 GHz–9.52 GHz) with a thickness of 2.5 mm. Thus, the component absorption materials can significantly decrease the weight of ferrite absorbers, ascribing to the thinner optimum thickness.

Solution-processable organic small molecules exhibiting the aggregation-induced emission (AIE) feature as electroluminescent (EL) emitters are very desirable because they can combine the low-cost solution processability of polymers, the reproducible well-defined structures of small molecules, and the strong solid-state fluorescence of AIE molecules; however, they are rarely reported. Herein, we first investigated the thermal stability, optical properties, stimuli-responsive behaviors, and application in solution-processed EL device of 2,6-bis(diethoxylphosphorylmethyl)-9,10-bis(N-alkylcarbazol-3-yl-vinyl)-anthracence (PAC8). PAC8 exhibited AIE behaviour, reversible mechanochromic luminescence, good thermal stability and strong crystalline green emission. More interestingly, PAC8 solution could be spin-coated into a good quality film, and the solution-processed non-doped EL device emitted 596 nm of orange-red light with peak luminous efficiencies (9.4 cd A−1 and 3.9 lm W−1) and external quantum efficiency up to 3.9%. This impressive EL performance signified that the pendent diethoxylphosphorylmethyl groups could be used as a promising avenue for improving the film-formation and EL performance.

The introduction of alkyl chains to the periphery of the conjugated skeleton of organic chromophores is generally to improve their solubility. However, a number of investigations show that the length of alkyl chains could affect significantly the solid-state molecular packing modes and optical and electronic properties, and thereby alkyl chains could play functional roles in tuning and altering the solid-state aggregation behavior and optoelectronic properties. While there have been a variety of reports on the impact of alkyl chains on organic field-effect transistor and photovoltaic performances, recently increasing interest has been paid to how the alkyl length affects the emission and stimuli responsive properties of organic fluorescent materials. This review focuses on alkyl length effects on solid-state fluorescence and mechanochromic behaviors, and the purpose is to arouse one's further attention to the alkyl-length effect in the design, synthesis and structure–property investigation of organic optoelectronic materials.

The torsion angle and distance between the donor (D) and the acceptor (A) are two important factors in determining the photoluminescence and electroluminescence properties of twisted D–A type organic molecules. Here, two new D–A compounds, 2-(10-butyl-10H-phenothiazin-3-yl)-5-phenyl-1,3,4-oxadiazole (PO) and 2-(4-(10-butyl-10H-phenothiazin-3-yl)phenyl)-5-phenyl-1,3,4-oxadiazole (PPO), were designed and synthesized to tune the torsion angle and distance between D and A moieties, and their photophysical and electroluminescence properties were investigated. The D–A type molecule PO has a planar conformation, whereas the D–π–A type molecule PPO has a twisted conformation because of the insertion of the phenyl bridge between the donor and the acceptor. Therefore, the charge transfer (CT) of PPO is much stronger than that of PO, and the singlet exciton yield of PPO may be higher than that of PO. On the other hand, the introduction of a phenyl unit can also improve the photoluminescence quantum efficiency (doped film ΦPL ≈ 70%). As a result, the PPO-doped device showed better device performance than PO. The device based on PPO as an emitter exhibited stable and high luminous efficiency (15.2 cd A−1, corresponding to an external quantum efficiency of 5.4%), which is increased by about 1.05 fold as compared to the device based on PO as an emitter (luminous efficiency 7.4 cd A−1 and external quantum efficiency 2.9%).

The version of this Article originally published online did not include a caution statement relating to safety concerns over some of the reagents used. All versions of the Article now have the following text included at the start of the Methods section “Caution: Sodium azide (NaN3) is highly toxic and also a potential explosion hazard; it can also react with organohalides to form explosive organic azides. Under acidic conditions, sodium azide can form hydrazoic acid (HN3) which is highly toxic. Considering these hazards, appropriate safety precautions should be taken when undertaking the C–C amination reactions reported in this Article.” Furthermore, in Fig. 2a, in the reaction conditions on the first equation it should have read DDQ not DDG; this has also been amended.

Aliphatic alcohols are common and bulk chemicals in organic synthesis. The site-selective functionalization of non-activated aliphatic alcohols is attractive but challenging. Herein, we report a silver-catalyzed δ-selective Csp3-H bond functionalization of abundant and inexpensive aliphatic alcohols. Valuable oximonitrile substituted alcohols are easily obtained by using well-designed sulphonyl reagents under simple and mild conditions. This protocol realizes the challenging δ-selective C–C bond formation of simple alkanols. Aliphatic alcohols usually require pre-activation for successful functionalization of their carbon chain. Here, the authors report a silver-catalyzed δ-selective functionalization of aliphatic alcohols via Csp3-H bond cleavage under mild conditions without the need of substrate pre-activation.

Anilines are fundamental motifs in various chemical contexts, and are widely used in the industrial production of fine chemicals, polymers, agrochemicals and pharmaceuticals. A recent development for the synthesis of anilines uses the primary amination of C-H bonds in electron-rich arenes. However, there are limitations to this strategy: the amination of electron-deficient arenes remains a challenging task and the amination of electron-rich arenes has a limited control over regioselectivity-the formation of meta-aminated products is especially difficult. Here we report a site-directed C-C bond primary amination of simple and readily available alkylarenes or benzyl alcohols for the direct and efficient preparation of anilines. This chemistry involves a novel C-C bond transformation and offers a versatile protocol for the synthesis of substituted anilines. The use of O2 as an environmentally benign oxidant is demonstrated, and studies on model compounds suggest that this method may also be used for the depolymerization of lignin.

Efficient and fully solution-processed blue organic light-emitting diodes (OLEDs) based on fluorescent small-molecule and methanol/water soluble conjugated polymer as electron-injection material are reported. The emitting layer is 3,6-bis(9,9,9′,9′-tetrakis (6-(9H-carbazol-9-yl)hexyl)-9H,9′H-[2,2′-bifluoren]-7-yl)dib-nzo[b, d]thiophene 5, 5-dioxide (OCSoC) with a blue-fluorescent small-molecule, and a methanol/water soluble polymer poly[(9,9-bis(30-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctyl-fluorene)] (PFN) acted as electron-injection layer (EIL). All the organic layers are spin-coated from solution. The multilayer device structure with emitting layer/electron-injection layer is achieved by solution-processed method without the dissolution problem between layers. The performances of the devices show that the maximum luminous efficiency of the multilayer device is increased about 43%, compared to the single-layer device. PFN acting as the EIL material plays a key role in the improvement of the device performance when used in solution-processed small-molecule OLEDs.

The dissipation behaviors of the two enantiomers of the organophosphorus pesticide malathion (MA) in environment samples were elucidated using a normal-phase high-performance liquid chromatography with a cellulose-tris(3,5-dimethylphenylcarbamate) (CDMPC) chiral column. A validated chiral residue analysis method in soil and water was established; the average recoveries for the two enantiomers were 88-102% in soil and 81-99% in water. Racemic and enantiopure R-(+)- and S-(-)-MA were incubated in five soil and water systems. The results of the degradation of racemate in all of the environment samples showed the inactive S-(-)-enantiomer degraded more rapidly than the active R-(+)-enantiomer, resulting in a relative enrichment of the R-form. Moreover, when the enantiopure S-(-)- and R-(+)-MA were incubated in three well-chosen soil and water samples, respectively, inversion from one enantiomer to another was found, indicating that using the optically pure enantiomer will not help to increase the bioactivity and reduce the environmental pollution.

Series of new 2-aryl-6-styryl-2,3-dihydropyridin-4(1H)-one derivatives were synthesized in acceptable to good yields by treatment of the curcuminoids with aqueous ammonia, the mechanism was proposed. By modification of the primary products, total 13 new compounds were obtained. The structures of all products were elucidated by spectroscopy analysis including HR-MS, 1 H NMR and 13 C NMR.

2,3,4,6-Tetra-O-benzyl-D-glucopyranose 1-α-(p-nitrobenzoate) reacted with aryl ethers in the presence of Lewis acid to give β-anomers stereoselectively in high yield, but reaction with 1,3-ditrimethylsilyloxybenzene gave α-anomer using BF3·Et2O and β-anomer using anhydrous AlCl3 as catalyst.