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N-Acylthioureas 1 can be easily transformed into 2,4-diamino-6-aryl-1,3,5-oxadiazinium salts 12, 2,4-diamino-6-aryl-1,3,5-thiadiazinium salts 13,3-amino-5-aryl-1,2,4-dithiazolium salts 19 and 2-acylimino-benzothiazolines 22, respectively by reaction with different electrophiles. The structure of the compounds prepared is confirmed by analytical data as well as by chemical transformations. 相似文献
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Florian Modicom Ellen M. G. Jamieson Elise Rochette Stephen M. Goldup 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(12):3915-3919
We report the unexpected discovery of a tandem active template CuAAC‐rearrangement process, in which N2 is extruded on the way to the 1,2,3‐triazole product to give instead acrylamide rotaxanes. Mechanistic investigations suggest this process is dictated by the mechanical bond, which stabilizes the CuI‐triazolide intermediate of the CuAAC reaction and diverts it down the rearrangement pathway; when no mechanical bond is formed, the CuAAC product is isolated. 相似文献
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Johannes Karges Uttara Basu Olivier Blacque Hui Chao Gilles Gasser 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14472-14478
The use of photodynamic therapy (PDT) to treat cancer has received increasing attention over the last years. However, the clinically used photosensitisers (PSs) have some limitations that include poor aqueous solubility, hepatotoxicity, photobleaching, aggregation, and slow clearance from the body, so the design of new classes of PSs is of great interest. We present the use of bis(dipyrrinato)zinc(II) complexes with exceptionally long lifetimes as efficient PDT PSs. Based on the heavy‐atom effect, intersystem crossing of these complexes changes the excited state from singlet to a triplet state, thereby enabling singlet oxygen generation. To overcome the limitation of quenching effects in water and improve water solubility, the lead compound 3 was encapsulated in a polymer matrix. It showed impressive phototoxicity upon irradiation at 500 nm in various monolayer cancer cells as well as 3D multicellular tumour spheroids, without observed dark toxicity. 相似文献
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Cai Sun Xiao‐Qing Yu Ming‐Sheng Wang Guo‐Cong Guo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9575-9578
Breaking the intrinsic rule of semiconductors that conductivity increases with increase of temperature and realizing a dramatic dropping of conductivity at high temperature may arouse new intriguing applications, such as circuit overload or over‐temperature protecting. This goal has now been achieved through T‐type electron‐transfer photochromism of one organic semiconductor assembled by intermolecular cation???π interactions. Conductivity of the viologen‐based model semiconductor (H2bipy)(Hox)2 (H2bipy=4,4′‐bipyridin‐1,1′‐dium; ox=oxalate) increased by 2 orders of magnitude after photoinduced electron transfer (a record for photoswitchable organic semiconductors) and generation of radical cation???π interactions, and fell by approximately 81 % at 100 °C through reverse electron transfer and degeneration of the radical cation???π interactions. The model semiconductor has at least two different electron transfer pathways in the decoloration process. 相似文献
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The 57Fe Mössbauer effect in [Fe(pythiaz)2] (BF4)2 (I) and [Fe(pythiaz)2] (C&O4)2 (II) has been studied between 298 and 4.2°K (pythiaz = 2,4-bis(2-pyridyl)thiazole). At 298°K compound I shows a doublet with ΔEQ(5T2) = 1.29 mm sec?1 and δ1S(5T2) = +0.93 mm sec?1 characteristic of a 5T2 ground state. At 236°K, a second doublet, typical for a 1A1 ground state appears. The transition 5T2 å 1A1 progresses as the temperature is lowered but levels off below ≈ 120°K. At 4.2°K, 59% of the intensity is due to the 1A1 state, and ΔEQ(1A1) = 1.59 mm sec?1 and δ1S(1A1) = +0.26 mm sec?1. In an applied magnetic field, Vzz(1A1) < 0 has been determined Similar results have been obtained with compound II.Debye-Waller factors f5T2 and f1A1. were determined from the Mössbauer spectra under the assumption of Curie-Weiss dependence of the magnetism for the 5T2 and constant μeff for the 1A1 ground state. The resulting temperature dependence of f1A1 is highly unusual thus suggesting complicated magnetic behaviour of both ground states in the transition region. Two mechanisms for the nature of the transition are discussed, a “spin-flip” mechanism being the physically more reasonable one. The assumption of a simple Boltzmann distribution (“spin equilibrium”) may be ruled out for the solid but could be encountered in solutions. 相似文献
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