- Roles of the methyl and methylene groups of mercapto acids in the photoluminescence efficiency and carrier trapping dynamics of CdTe QDs
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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.
- Chandra Sekhar,De, Apurba,Hossain, Sk Saddam,Samanta, Anunay
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Read Online
- Synthesis of macrocyclic and medium-sized ring thiolactonesviathe ring expansion of lactams
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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.
- Palate, Kleopas Y.,Epton, Ryan G.,Whitwood, Adrian C.,Lynam, Jason M.,Unsworth, William P.
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supporting information
p. 1404 - 1411
(2021/02/27)
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- Green method for synthesizing high value-added mercaptoacid by catalyzing addition reaction of H2S and olefine acid by using ionic liquid as catalyst
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The invention relates to a green method integrating catalysis, reaction and separation, which is used for producing beta-mercapto carboxylic acid through addition of alpha, beta-unsaturated carboxylic acid and H2S by taking amino-functionalized hydrophobic ionic liquid as a catalyst. H2S is activated through tertiary amine alkaline sites contained in the ionic liquid, so that H2S and double bonds of alpha, beta-unsaturated carboxylic acid are subjected to an addition reaction, and recycling of H2S is realized. The product obtained after the reaction can be subjected to water phase liquid-liquid extraction to realize separation of the catalyst and the product, and the ionic liquid can be recycled. In the system, the ionic liquid is both a catalytic medium and a reaction medium, no other organic solvent participates in the system, H2S is efficiently utilized, meanwhile, high-added-value products such as mercapto acid are obtained, and the method is more economical and environmentally friendly and conforms to the development concept of green chemical industry.
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Paragraph 0041; 0051-0052
(2021/05/05)
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- Ruthenium(II)–Arene Thiocarboxylates: Identification of a Stable Dimer Selectively Cytotoxic to Invasive Breast Cancer Cells
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RuII-arene complexes provide a versatile scaffold for novel anticancer drugs. Seven new RuII-arene-thiocarboxylato dimers were synthesized and characterized. Three of the complexes (2 a, b and 5) showed promising antiproliferative activities in MDA-MB-231 (human invasive breast cancer) cells, and were further tested in a panel of fifteen cancerous and noncancerous cell lines. Complex 5 showed moderate but remarkably selective activity in MDA-MB-231 cells (IC50=39±4 μm Ru). Real-time proliferation studies showed that 5 induced apoptosis in MDA-MB-231 cells but had no effect in A549 (human lung cancer, epithelial) cells. By contrast, 2 a and b showed moderate antiproliferative activity, but no apoptosis, in either cell line. Selective cytotoxicity of 5 in aggressive, mesenchymal-like MDA-MB-231 cells over many common epithelial cancer cell lines (including noninvasive breast cancer MCF-7) makes it an attractive lead compound for the development of specifically antimetastatic Ru complexes with low systemic toxicity.
- Stephens, Liam J.,Levina, Aviva,Trinh, Iman,Blair, Victoria L.,Werrett, Melissa V.,Lay, Peter A.,Andrews, Philip C.
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p. 1188 - 1200
(2019/12/24)
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- Preparation method of beta-sulfhydryl carboxylic acid compound
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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.
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Paragraph 0072; 0077; 0078
(2018/06/26)
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- Flavouring and odorant thiols from renewable natural resources by InIII-catalysed hydrothioacetylation and lipase-catalysed solvolysis
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A chemoenzymatic access to thiol compounds, including ethyl 3-thiobutanoate, 3-thio-p-menthene and 8-thio-p-menthan-2-one, three compounds of interest in flavour and fragrance chemistry presenting various fruity notes, is proposed. It involves an indium(III)-catalysed hydrothioacetylation of renewable precursors followed by an enzymatic solvolysis of the obtained thioesters by lipases in aqueous or organic solvents.
- Dia, Reine-Marie,Belaqziz, Rim,Romane, Abderrahmane,Antoniotti, Sylvain,Du?ach, Elisabet
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scheme or table
p. 2164 - 2167
(2010/06/13)
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- METHOD OF PRODUCING β-MERCAPTOCARBOXYLIC ACIDS
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The invention relates to a method for efficiently producing β-mercaptocarboxylic acids using a solid acid catalyst such as zeolite, which product corresponds to respective starting materials selected from α, β-unsaturated carboxylic acids (α, β-unsaturated carboxylic acid, a, β-unsaturated carboxylic acid ester, ex, β-unsaturated amide, a, β-unsaturated aldehide and α, β-unsaturated ketone) and hydrogen sulfides (hydrogen sulfide, sulfide salt and hydrosulfide salt), wherein a solvent compatible with water is used in the reaction. According to the invention, β-mercaptocarboxylic acids which are useful as additives in synthetic materials for pharmaceutical or agricultural agents and in polymer compounds can be industrially produced efficiently by using easily available a, β-unsaturated carboxylic acid (such as crotonic acid) at high yield.
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Page/Page column 28-29
(2009/04/25)
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- METHOD FOR PRODUCING -MERCAPTO CARBOXYLIC ACIDS
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An object of the present invention is to provide a method for industrially producing beta-mercapto carboxylic acids that are useful as synthetic raw materials for medicines and agrochemicals or as additives for polymer compounds from easily available alpha,beta-unsaturated carboxylic acids in high yields and productivity. The present invention is characterized in that a solvent having an amide group and represented by the formula (1) is used when the alpha,beta-unsaturated carboxylic acids are reacted with hydrogen sulfides to produce the beta-mercapto carboxylic acids. Particularly, it is more preferable to carry out the reaction at a pH range of 6.0 to 8.5: (In the formula (1), R1 represents any one of a hydrogen atom, an alkoxy group having 1 to 5 carbon atoms, an alkyl group having 1 to 5 carbon atoms, an amino group, and an alkylamino group having 1 to 5 carbon atoms; R2 and R3 each represents independently any one of a hydrogen atom and an alkyl group having 1 to 5 carbon atoms; when both R2 and R3 are not a hydrogen atom, R2 and R3 may together form a ring structure through an alkylene group; and when both R1 and R2 are not a hydrogen atom, R1 and R2 may form a ring structure through an alkylene group).
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Page/Page column 51; 52
(2009/10/22)
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- Downfield chemical shifts at α-protons and carbons of β-propiothiolactones
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Both the α-protons and carbons of β-propiothiolactones exhibit atypical downfield chemical shifts. The α-protons of β-propiothiolactones with no heteroatom at the α-position appear at 3.53-5.35ppm, whereas the α-carbons appear at 56.9-86.2 ppm. The major cause of the unexpected deshielding effect was rationalized by assuming a through-space interaction between the occupied orbital of the α-carbon and the vacant orbital of sulfur. Copyright
- Lee, Hee Bong,Park, Hyung-Yeon,Lee, Bon-Su,Kim, Young Gyu
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p. 468 - 471
(2007/10/03)
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- Thiopyrano[2,3,4-cd]indoles as 5-lipoxygenase inhibitors: Synthesis, biological profile, and resolution of 2-[2-[1-(4-chlorobenzyl)-4-methyl-6- [(5-phenylpyridin-2-yl)methoxy]-4,5-dihydro-1H-thiopyrano[2,3,4-cd]indol-2- yl]ethoxy]butanoic acid
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Leukotriene biosynthesis inhibitors have potential as new therapies for asthma and inflammatory diseases. The recently disclosed thiopyrano[2,3,4- cd]indole class of 5-lipoxygenase (5-LO) inhibitors has been investigated with particular emphasis on the side chain bearing the acidic functionality. The SAR studies have shown that the inclusion of a heteroatom (O or S) in conjunction with an α-ethyl substituted acid leads to inhibitors of improved potency. The most potent inhibitor prepared contains a 2-ethoxybutanoic acid side chain. This compound, 14d (2-[2-[1-(4-chlorobenzyl)-4-methyl-6-[(5- phenylpyridin-2-yl)methoxy]-4,5-dihydro-1H-thiopyrano[2,3,4-cd]indol-2- yl]ethoxy]butanoic acid, L-699,333), inhibits 5-HPETE production by human 5- LO and LTB4 biosynthesis by human PMN leukocytes and human whole blood (IC50s of 22 nM, 7 nM and 3.8 μM, respectively). The racemic acid 14d has been shown to be functionally active in a rat pleurisy model (inhibition of LTB4, ED50 = 0.65 mg/kg, 6 h pretreatment) and in the hyperreactive rat model of antigen-induced dyspnea (50% inhibition at 2 and 4 h pretreatment; 0.5 mg/kg po). In addition, 14d shows excellent functional activity against antigen-induced bronchoconstriction in the conscious squirrel monkey [89% inhibition of the increase in R(L) and 68% inhibition in the decrease in C(dyn) (0.1 mg/kg, n = 3)] and in the conscious sheep models of asthma (iv infusion at 2.5 μg/kg/min). Acid 14d is highly selective as an inhibitor of 5-LO activity when compared to the inhibition of human 15-LO, porcine 12-LO and ram seminal vesicle cyclooxygenase (IC50 > 5 μM) or competition in a FLAP binding assay (IC50 > 10 μM). Resolution of 14d affords 14g, the most potent diastereomer, which inhibits the 5-HPETE production of human 5-LO and LTB4 biosynthesis of human PMN leukocytes and human whole blood with IC50s of 8 nM, 4 nM, and 1 μM respectively. The in vitro and in vivo profile of 14d is comparable to that of MK-0591, which has showed biochemical efficacy in inhibiting ex vivo LTB4 biosynthesis and urinary LTE4 excretion in clinical trials.
- Hutchinson,Riendeau,Brideau,Chan,Falgueyret,Guay,Jones,Lepine,Macdonald,McFarlane,Piechuta,Scheigetz,Tagari,Therien,Girard
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p. 1153 - 1164
(2007/10/02)
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- Development of a Linker with an Enhanced Stability for the Preparation of Peptide Thioesters and Its Application to the Synthesis of a Stable-Isotope-Labelled HU-Type DNA-Binding Protein
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An S-alkyl-thioester-moiety-containing linker with an enhanced stability on a resin has been developed.A linker containing S-alkyl thioester with a spacer group, -CO-SC(CH3)2CH2CO-Nle-, was stable during the peptide chain elongation cycle.This thioester was stable under HF treatment conditions, and was rapidly activated by silver ions in the presence of N-hydroxysuccinimde (HONSu) to form a peptide bond.Using this linker, peptide segments covering the HU-type DNA-binding protein of Bacillus stearothermophilus (HBs), which was site-specifically labelled with 2H, 13C,and 15N, were prepared.Using these peptide segments, multi-labelled HBs was synthesized.Distinct signals of 2H, 13C, and 15N in HBs were detected by NMR spectrometry.
- Hojo, Hironobu,Kwon, Yeondae,Kakuta, Yoshimitsu,Tsuda, Sakae,Tanaka, Isao,et al.
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p. 2700 - 2706
(2007/10/02)
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- Azole derivatives
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Azole derivatives of the formula SPC1 Wherein R1 is free or esterified carboxyl or other functionally modified carboxyl group, R2 and R3 each are aryl; A is Cn H2n in which n is an integer from 1 to 10, inclusive; and Z is O or S; and the physiologically acceptable salts thereof, possess, with good compatibility, excellent antiphlogistic activity and, in particular, influence favorably the chronic progressive diseases of the joints, e.g., arthritis. They can be prepared from compounds of the formula SPC2 Wherein X1 is a group convertible into the group --S--A--R1, and R2 and R3 have the values given above.
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