2423-29-2Relevant articles and documents
Tunable NIR-II emitting silver chalcogenide quantum dots using thio/selenourea precursors: Preparation of an MRI/NIR-II multimodal imaging agent
Basel, Siddhant,Bhardwaj, Karishma,Borthakur, Sukanya,Brito, Beatriz,Clarke, Mitchell,Pariyar, Anand,Pradhan, Sajan,Roy, Pankaj,Saikia, Lakshi,Shankar, Amit,Stasiuk, Graeme J.,Tamang, Sudarsan,Thapa, Surakcha
supporting information, p. 15425 - 15432 (2020/11/18)
Aqueous-stable, Cd- and Pb-free colloidal quantum dots with fluorescence properties in the second near-infrared region (NIR-II, 1000-1400) are highly desirable for non-invasive deep-tissue optical imaging and biosensing. The low band-gap semiconductor, silver chalcogenide, offers a non-toxic and stable alternative to existing Pd, As, Hg and Cd-based NIR-II colloidal quantum dots (QDs). We report facile access to NIR-II emission windows with Ag2X (X = S, Se) QDs using easy-to-prepare thio/selenourea precursors and their analogues. The aqueous phase transfer of these QDs with a high conservation of fluorescence quantum yield (retention up to ～90%) and colloidal stability is demonstrated. A bimodal NIR-II/MRI contrast agent with a tunable fluorescence and high T1 relaxivity of 408 mM-1 s-1 per QD (size ～ 2.2 nm) and 990 mM-1 s-1 per QD (size ～ 4.2 nm) has been prepared by grafting 50 and 120 monoaqua Gd(iii) complexes respectively to two differently sized Ag2S QDs. The size of the nanocrystals is crucial for tuning the Gd payload and the relaxivity.
Synthesis of isothiocyanates by reaction of amines with phenyl chlorothionoformate via one-pot or two-step process
Li, Zheng-Yi,Ma, Hong-Zhao,Han, Chen,Xi, Hai-Tao,Meng, Qi,Chen, Xin,Sun, Xiao-Qiang
, p. 1667 - 1674 (2013/07/19)
A facile and efficient synthesis of isothiocyanates from amines is described. This method involves the reaction of amines with phenyl chlorothionoformate in the presence of solid sodium hydroxide by either a one-pot process or a two-step approach. The one-pot process is useful for preparing alkyl and electron-rich aryl isothiocyanates, whereas the two-step approach is more versatile, working very well not only for alkyl and electron-rich aryl isothiocyanates, but also for highly electron-deficient aryl and heterocyclic isothiocyanates. Georg Thieme Verlag Stuttgart, New York.
Aminolysis of aryl chlorothionoformates with anilines in acetonitrile: Effects of amine nature and solvent on the mechanism
Oh, Hyuck Keun,Ha, Joo Suk,Sung, Dae Dong,Lee, Ikchoon
, p. 8219 - 8223 (2007/10/03)
The aminolysis of aryl chlorothionoformates (7, YC6H 4OC(=S)Cl) with anilines (XC6H4NH2) in acetonitrile at 5.0 °C has been investigated. The rates are slower than those for the corresponding reactions of aryl chloroformates (6, YC 6H4OC(=O)Cl). This rate sequence is a reverse of that for alkyl chloroformates (1 4) in water, for which rate-limiting formation of a tetrahedral intermediate, T±, is predicted. On the basis of the large negative cross-interaction constant, ρXY = -0.77, failure of the reactivity-selectivity principle, normal kH/k D values involving deuterated nucleophiles (XC6H 4ND2), and low ΔH≠ with large negative ΔS≠ values, a concerted mechanism with a four-membered hydrogen bonded cyclic transition state (11) is proposed for the title reaction series. It has been shown that the solvent change from water to acetonitrile for the aminolysis of 6 and 7 causes a mechanistic change from stepwise to concerted.
