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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]

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]

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]