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The unique features of solution‐processed quantum dots (QDs) including emission tunability in the visible range, high‐quality saturated color and outstanding intrinsic stability in environment are highly desired in various application fields. Especially, quantum dot light‐emitting diodes (QLEDs) are promising light sources for applications in displays. However, the imbalance injection of holes and electrons have always been a challenging issue of QLED. In this study, the modified ligands which is synthesized by ourselves are incorporated into QDs through solution ligand exchange. The highest occupied molecular orbital (HOMO) of QDs is upshifted from ‐5.65eV to ‐5.35eV, leading to the decrement of the energy gap between the HOMO of QDs and the HOMO of hole transport layer. Through the successful ligands exchange, improvement by factors of 7.5 is achieved in maximum external quantum efficiency (EQE) compared with QLED with OA ligands. [ABSTRACT FROM AUTHOR]

Heat‐resistant energetic material (HREM) has shown its broad applications in petroleum and natural gas exploration, aerospace vehicle as well as solid rocket formulations. Benzopyridotetraazapentalene (BPTAP) (d: 1.84 g cm−3, D: 7670 m s−1, IS: 9 J, Td: 366 °C) is a heat‐resistant energetic material, which is more dense and energetic than those of commercial HREM hexanitrosilbene (HNS) (d: 1.74 g cm−3, D: 7612 m s−1, IS: 5 J, Td: 318 °C). However, low solubility in most of commonly‐used solvents has restricted its applications in detonators as nano‐energetic materials. Meanwhile, recognition on this fused organic backbone is still limited. Herein, we report a chlorine‐inclusion strategy and facile approaches to yield three new derivatives of BPTAP. It is notable that compound 6‐a exhibits its high density (1.92 g cm−3), superior thermal stability (Td: 334 °C), high detonation performance (D: 8084 m s−1), comparable sensitivity (IS: 3 J) to that of HNS, surpassing those of commercially‐used highly‐sensitive primary energetic material lead azide (LA). It is interesting that the chlorine‐inclusion in different position of fused benzopyridotetraazapentalene framework has greatly affected their physical properties such as crystal structure, thermal stability and sensitivity. This investigation offers a unique perspective for deeply exploring the relationship between structure and performance of energetic materials. [ABSTRACT FROM AUTHOR]

In this study, by selecting the carrier injection and transport materials and optimizing the thickness of each functional layer in the device, we have solved the problem of unbalanced carrier injection in quantum dot light‐emitting diodes (QLED). The current efficiencies of red, green and blue spin‐coating QLED devices reach 30 cd/A, 70 cd/A, and 8 cd/A, respectively. By continuous optimization of the ink‐jet printing and film‐forming process, the suitable volume of printed ink drops and drying process conditions are obtained, and completed the fabrication of 55‐inch UHD AMQLED display. [ABSTRACT FROM AUTHOR]

Abstract: Synthesizing energetic metal–organic frameworks at ambient temperature and pressure has been always a challenge in the research area of energetic materials. In this work, through in situ controllable synthesis, energetic metal–organic framework gem‐dinitromethyl‐substituted dipotassium 4,5‐bis(dinitromethyl)‐1,2,3‐triazole with a “cage‐like” crystal packing was obtained and characterized. Most importantly, for the first time, we found that it could be successfully afforded with a catalytic effect of trifluoroacetic acid. This new compound exhibited its high density (2.04 g cm−3) at ambient temperature, superior detonation velocity (8715 m s−1) to that of lead azide (5877 m s−1) and comparable to that of RDX (8748 m s−1). Its detonation products are mainly N2 (48.1 %), suggesting it is also a green energetic material. The above‐mentioned performance indicates its potential applications in detonator devices as lead‐free primary explosive. [ABSTRACT FROM AUTHOR]

Modifying the properties of energetic materials is important not only for gaining insight into the relationship between structures and properties but also for multiple applications. A new family of energetic compounds, polynitroimidazoles featuring trinitromethyl, nitromethyl and methyl acetate moieties at the nitrogen position of heterocyclic rings were synthesized. The high‐energy oxidizers 2‐nitro and 4‐nitro‐1‐(trinitromethyl)‐1H‐imidazoles were obtained by nitration of 1‐acetonylpolynitroimidazoles in fuming HNO3 and concentrated H2SO4. 4,5‐Dinitro‐1‐(nitromethyl)‐1H‐imidazole and 4,5‐dinitro‐1‐(acetate methyl)‐1H‐imidazole were afforded by using 68 % HNO3 and concentrated H2SO4 through controllable synthesis. All the intermediates and the target compounds were confirmed by X‐ray diffraction. It is noteworthy that one of the N‐trinitromethyl nitroimidazole derivatives showed high density (ρ: 1.88 g cm−3), attractive positive oxygen balance (Ω: +18.3 %) and good detonation performance (D: 9003 m s−1) exceeding those of ADN, while N‐nitromethyl derivative behaved higher thermal stability and lower sensitivity in contrast to those of NG. N‐acetate methyl derivative gave an interesting melt‐castable property (Tm.p.: 86 oC, Td: 224 oC), acceptable detonation performance as well as low sensitivity towards impact and friction (IS>40 J, FS>360 N), making it a competitive replacement for DNAN. These chemical and physical properties indicate that these novel materials show promising energetic performance towards future applications. [ABSTRACT FROM AUTHOR]

A metal-free oxyboration reaction, in which no acidic proton is involved and no intermediates bearing B−O σ-bond were observed, was recently reported by the Blum group. Since it showed potential as a general strategy to synthesize heterocyclic boronic esters, understanding the mechanistic details is very important. Two possible pathways of this oxyboration reaction were examined. Moreover, three key processes were highlighted in the pathway, including borylative cyclization, chloride shift, and demethylation. According to the calculations, the early demethylation (which leads to a formal O−B bond) was found to be slightly exergonic, but to have an inaccessible barrier, whereas demethylation after the cyclization step was feasible. The rate-determining step (RDS) was identified as the intramolecular cyclization for the oxyboration. Further theoretical investigation on the model reaction, in which an indole boronic ester is the product, revealed some interesting differences of reactivity between oxygen and nitrogen. Based on our calculation results, the N−C bond, which is usually treated as inert, can be cleaved in this case. Moreover, the there is a strong tendency for the RDS to shift from cyclization (as observed in the former oxyboration) to demethylation. Experiments were also conducted to confirm the calculations. [ABSTRACT FROM AUTHOR]

We have synthesized a series of new β-iminoenolates and their corresponding difluoroboron complexes without any traditional gelation moieties, and some of them were able to gelatinize organic solvents. It was found that the presence of halogen atoms as substituents had a significant effect on gelation ability. In particular, bromo-containing compounds 4 A and 4 B exhibited excellent gelation abilities compared with other halogen-substituted gelators. By analyses of the single-crystal structure, the PXRD pattern of the xerogel, and electronic spectral changes during gelation, we deemed that π-π, C−H⋅⋅⋅F, and C−H⋅⋅⋅Br interactions were the driving forces for the gelation of 4 B. Interestingly, ( Z)-1-(4-bromophenyl)-2-(3-methylpyrazin-2-yl)ethen-1-ol ( 8 A), prepared in this work, is the lowest-molecular-weight organogelator to have been reported. It should be noted that although β-iminoenolates 3 A- 5 A are nonemissive in solution, they emit strong yellow light in organogels, which suggests aggregation-induced emissive activity, whereas the difluoroboron complexes 3 B- 5 B show strong fluorescence in solutions, organogels, and xerogel-based films. Moreover, we found that the emission of 4 B in a nanofiber-based film could be quenched significantly upon exposure to gaseous trifluoroacetic acid and that the decay time and detection limit were 0.5 s and 0.17 ppm, respectively. Thus, through this work we have provided a new strategy for the design of nontraditional π gelators by introducing halogen atoms into π-conjugated systems with moderate polarities. [ABSTRACT FROM AUTHOR]

An L-phenylalanine derivative ( C12PhBPCP) consisting of a strong emission fluorophore with benzoxazole and cyano groups is designed and synthesized to realize dual responses to volatile acid and organic amine vapors. The photophysical properties and self-assembly of the said derivative in the gel phase are also studied. C12PhBPCP can gelate organic solvents and self-assemble into 1 D nanofibers in the gels. UV/Vis absorption spectral results show H-aggregate formation during gelation, which indicates strong exciton coupling between fluorophores. Both wet gel and xerogel emit strong green fluorescence because the cyano group suppresses fluorescence quenching in the self-assemblies. Moreover, the xerogel film with strong green fluorescence can be used as a dual chemosensor for quantitative detection of volatile acid and organic amine vapors with fast response times and low detection limits owing to its large surface area and amplified fluorescence quenching. The detection limits are 796 ppt and 25 ppb for gaseous aniline and trifluoroacetic acid (TFA), respectively. [ABSTRACT FROM AUTHOR]

Nanofibers based on phenanthroimidazole derivatives PCC, PDC, and PSC were fabricated by organogelation processes, and their fluorescence sensory properties towards acid were investigated. It was found that the emission of PCC in the nanofiber-based film could be quenched significantly upon exposure to gaseous TFA due to the formation of protonated PCC, in which ICT (intramolecular charge transfer) would occur. On the other hand, TFA vapor led to the emitting colors of PDC and PSC in the nanofiber-based films to turn to yellow and green from sky blue and blue, respectively. Additionally, we found that the decay times of PCC were 0.1 s and 1.9 s in probing the saturated vapor of TFA in nanofiber-based film and in spin-coated film, respectively. The results suggested that the high surface-to-volume ratio and large interspace in the nanofiber-based networks favored the enhanced adsorption, accumulation, and diffusion of gaseous molecules, resulting in such a high performance. [ABSTRACT FROM AUTHOR]

Two L-phenylalanine derivatives with 5,8-bis(2-(carbazol-3-yl)vinyl)quinoxaline ( PCQ) and 5,8-bis[2-(carbazol-3-yl)]-2,3-dimethylquinoxaline ( DCQ) as fluorophores were synthesized, and their photophysical properties were measured and compared. The two compounds were found to gelate some organic solvents and self-assemble into 1D nanofibers in gels. The wet gel of PCQ emitted a weak orange fluorescence, but the DCQ gel had a strong green one. This result can be due to the presence of two methyl groups and the nonplanar conformation of fluorophore in DCQ. The gel film of DCQ also showed significantly stronger fluorescence than that of PCQ. Thus, the wet gel and xerogel film of DCQ were selected to study their sensing properties to acids. The yellow wet gel of DCQ transformed into a brown sol upon the addition of 0.2 equiv trifluoroacetic acid (TFA), accompanied by emission quenching. The xerogel film of DCQ rapidly responded to volatile acids, such as TFA, HCl, and HOAc. The fluorescence of the xerogel film was gradually quenched with increased concentration of volatile acid vapors. The fibrous film exhibited low detection limits for volatile acid. The detection limits of the thin films for TFA, HCl, and HOAc reached 43, 122, and 950 ppb, respectively. [ABSTRACT FROM AUTHOR]