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Chloro- and Dichloro-methylsulfonyl Nitrenes: Spectroscopic Characterization, Photoisomerization, and Thermal Decomposition
摘要： Chloro- and dichloro-methylsulfonyl nitrenes, CH2ClS(O)2N and CHCl2S(O)2N, have been generated from UV laser photolysis (193 and 266 nm) of the corresponding sulfonyl azides CH2ClS(O)2N3 and CHCl2S(O)2N3, respectively. Both nitrenes have been characterized with matrix-isolation IR and EPR spectroscopy in solid N2 (10 K) and glassy toluene (5 K) matrices. Triplet ground-state multiplicity of CH2ClS(O)2N (|D/hc| = 1.57 cm?1 and |E/hc| = 0.0026 cm?1) and CHCl2S(O)2N (|D/hc| = 1.56 cm?1 and |E/hc| = 0.0042 cm?1) has been confirmed. In addition, dichloromethylnitrene CHCl2N (|D/hc| = 1.57 cm?1 and |E/hc| = 0 cm?1), formed from SO2-elimination in CHCl2S(O)2N, has also been identified for the first time. Upon UV light irradiation (365 nm), the two sulfonyl nitrenes R–S(O)2N (R = CH2Cl and CHCl2) undergo concomitant 1,2-R shift to N-sulfonlyamines R–NSO2 and 1,2-oxygen shift to S-nitroso compounds R–S(O)NO, respectively. The identification of these new species with IR spectroscopy is supported by 15N labeling experiments and quantum chemical calculations at the B3LYP/6-311++G(3df,3pd) level. In contrast, the thermally-generated sulfonyl nitrenes CH2ClS(O)2N (600 K) and CHCl2S(O)2N (700 K) dissociate completely in the gas phase, and in both cases, HCN, SO2, HCl, HNSO, and CO form. Additionally, ClCN, OCCl2, HNSO2, ?NSO2, and the atmospherically relevant radical ?CHCl2 are also identified among the fragmentation products of CHCl2S(O)2N. The underlying mechanisms for the rearrangement and decomposition of CH2ClS(O)2N and CHCl2S(O)2N are discussed based on the experimentally-observed products and the calculated potential energy profile.
关键词： decomposition,nitrenes,azides,reaction mechanism,photoisomerization,matrix isolation
更新于2025-09-19 17:15:36
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - New Type Metal-Azides for Low Threshold Laser Initiation
摘要： The exploration and mining of minerals on extraterrestrial bodies in the solar system: planets, moons, planetoids, asteroids and comets requires the development of fundamentally new primary explosives that are not subject to spontaneous detonation during vibration and static discharges when launched from the ground. Available detonators do not fully meet these requirements and pose a danger to future space missions, therefore, are considered undesirable as payload on board. Therefore, the synthesis, research and testing of new energetic materials sensitive exclusively to the selected wavelength, duration and energy of the exciting laser pulses is of particular relevance. Laser radiation is delivered to the detonator by means of an optical fiber, which imposes an upper limit on the energy of the pulses. In addition, lasers for space missions should be quite miniature, consume little power and do not require cooling. Therefore, it is necessary to pay special attention to lowering the threshold for laser initiation of energetic materials. In this work, we synthesized and investigated energetic materials based on both nontrivial and well-known azides with the ultimate goal of reducing the laser initiation threshold.
关键词： metal-azides,energetic materials,laser initiation,space missions,primary explosives
更新于2025-09-12 10:27:22
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Proton-transfer based azides with fluorescence off–on response for detection of hydrogen sulfide. An experimental, theoretical and bioimaging study
摘要： This work describes the synthesis of photoactive proton transfer compounds based on the benzazolic core containing the azide group. The compounds present absorption in the UV region and fluorescence emission in the visible region of the spectra with large Stokes shift due to a phototautomerism in the excited state (ESIPT). The azide location on the benzazolic structure showed to present a noteworthy role on their photophysics leading to fluorescence quenching. A photophysical study was performed in the presence of NaHS to evaluate their application as H2S sensor. The methodology employed was the reduction of azides to amines using NaHS to mimic H2S, resulting in an off–on response fluorescence mechanism. The observed photophysical features were successfully used to explore the azides as fluorescent probes in biological media. In addition, DFT and TD-DFT calculations with CAM-B3LYP/cc-pVDZ and CAM-B3LYP/jun-cc-pVTZ level respectively were performed in order to understand the photophysics features of azide derivatives, where the main interest was investigate fluorescence quenching experimentally observed in the azide derivatives.
关键词： optical sensor,TD-DFT,fluorescence,ESIPT,azides
更新于2025-09-09 09:28:46