26473-49-4Relevant articles and documents
Roles of the methyl and methylene groups of mercapto acids in the photoluminescence efficiency and carrier trapping dynamics of CdTe QDs
Chandra Sekhar,De, Apurba,Hossain, Sk Saddam,Samanta, Anunay
, p. 1536 - 1542 (2017)
Surface protection using an appropriate ligand is essential for controlling the size, stability and luminescence properties of the quantum dots (QDs). Though 3-mercaptopropanoic acid (3-MPA) is regarded as the most suitable protecting ligand among the mercapto acids for water soluble CdTe QDs, one receives a different picture from recent studies, which report a much higher luminescence efficiency of 3-mercaptobutyric acid (3-MBA) capped QDs compared with those capped by 3-MPA and attribute the observation to the influence of the side methyl group of mercapto acids. Herein we report the luminescence properties and carrier trapping dynamics of four different, but structurally related mercapto acid capped CdTe QDs prepared using a different method. The results show that these QDs are much more fluorescent than those prepared directly in an aqueous environment and surprisingly, no enhanced luminescence for the QDs capped by mercapto acids containing a side methyl group is observed. Ultrafast pump-probe measurements confirm these results in addition to providing insight into the carrier trapping dynamics of these systems. It is shown that our findings, which appear to be in conflict with the recent literature, can be rationalized and the exact role of the side methyl group of the mercapto acids can be understood by careful analysis of the results taking into consideration the difference in the methods of preparation of the QDs in the two cases.
Synthesis of macrocyclic and medium-sized ring thiolactonesviathe ring expansion of lactams
Palate, Kleopas Y.,Epton, Ryan G.,Whitwood, Adrian C.,Lynam, Jason M.,Unsworth, William P.
supporting information, p. 1404 - 1411 (2021/02/27)
A side chain insertion method for the ring expansion of lactams into macrocyclic thiolactones is reported, that can also be incorporated into Successive Ring Expansion (SuRE) sequences. The reactions are less thermodynamically favourable than the analogous lactam- and lactone-forming ring expansion processes (with this notion supported by DFT data), but nonetheless, three complementary protecting group strategies have been developed to enable this challenging transformation to be achieved.
Preparation method of beta-sulfhydryl carboxylic acid compound
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Paragraph 0072; 0077; 0078, (2018/06/26)
The invention provides a preparation method of a beta-sulfhydryl carboxylic acid compound. A solid base catalyst used in the method has suitable alkali strength, so that not only is hydrogen sulfide enabled to be activated and a reaction promoted to be carried out, but the binding between carboxyl groups and active sites in raw materials or products is also inhibited, and the active sites are prevented from being deactivated slowly. Furthermore, the solid base catalyst selects a polyhydroxy compound as a carrier, and a great deal of hydroxyl groups on the surface of the carrier can promote thehydrogen sulfide to be dissolved in a reaction system and adsorbed on the surface of the catalyst so as to enable the hydrogen sulfide to be migrated to the positions around the active sites for being activated, so that the high conversion rate and high selectivity of the reaction also can be enabled to be reached at the lower pressure, and the catalytic stability is better. In addition, the preparation method is mild in reaction conditions, and the gas-liquid phase reaction is carried out under the conditions of low temperature and low pressure, so that the method is easily applied to industry. Experiments prove that the reaction conversion rate and selectivity of the beta-sulfhydryl carboxylic acid compound prepared by the method are respectively not less than 98% and 88%. After the compound is continuously evaluated for 100h, the catalytic stability of the compound is proved to be better.
