Selective synthesis and ester cleavage property of 3,2-anhydro-3-deoxy-3-thio-β-cyclodextrin

The title compound was synthesized by the conversion of 2^A,3^A-alloepoxy-β-cyclodextrin to the 2^A,3^A-mannoepithio derivative with thiourea and subsequent ring-opening by intramolecular nucleophilic substitution. Its thiol group and the distorted cavity demonstrated good synergetic effect in promoting the cleavage of m-nitrophenyl acetate but did not cooperate with each other toward the p-isomer.     

Modified polypropylene fabrics and their metal ion sorption role in aqueous solution

Polypropylene non-woven fabrics were grafted with glycidyl methacrylate by the electron beam irradiation method and the introduced epoxide rings were chemically conversed to hydroxyl and thiol groups. The modified polypropylene fabrics showed sufficient hydrophilicity to adsorb the metal ions from the aqueous solutions. The modified fibers were examined as adsorbents for metal ions dissolved in seawater and its model solutions at various conditions. The amount of ions adsorbed on the fabrics was determined by a sequential plasma spectrometry. The modified polypropylene fabrics adsorbed extremely high amount of Au(III) and Hg(II) ions. The equilibrium adsorption of Au(III) was almost not disturbed, even if Cu(II), Cd(II), Pb(II) and the other ions coexisted in the same aqueous solution. Nowadays, the most widely advantages of this technique are the recovery of metal ions dissolved in water and the treatment of industrial wastewater systems.     

The regulation of biothiol-responsive performance and bioimaging application of benzo[c][1,2,5]oxadiazole dyes

The different oxidation states of sulphur atom play a significant role on functional materials. In this work, a aryl-thioether and its sulphone substituted benzo[c][1,2,5]oxadiazole dyes were synthesized and utilized to determine thiol-containing amino acids. The result of selectivity experiments showed they detected the cysteine and homocysteine under physiological condition with negligible interference from other amino acids. In comparison to the thioether dye, the sulphone-based dye exhibited much faster response time for Cys and Hcy. However, the sulphone restricted its thiol-reactivity and bioimaging performance in living cells. By reducing the oxidation state of sulphur atom, we amazedly found that the sulfoxide-based dye still maintained high selectivity ultrafast response time for Cys/Hcy under physiological condition. It was worth mentioning that it also had high reactivity and good bioimaging performance that sulfone compounds did not have.     

Fluorescence resonance energy transfer between green fluorescent protein and doxorubicin enabled by DNA nanotechnology

DNA nanotechnology is a rapidly growing research area, where DNA may be used for wide range of applications such as construction of nanodevices serving for large scale of diverse purposes. Likewise a panel of various purified fluorescent proteins is investigated for their ability to emit their typical fluorescence spectra under influence of particular excitation. Hence these proteins may form ideal donor molecules for assembly of fluorescence resonance emission transfer (FRET) constructions. To extend the application possibilities of fluorescent proteins, while using DNA nanotechnology, we developed nanoconstruction comprising green fluorescent protein (GFP) bound onto surface of surface active nanomaghemite and functionalized with gold nanoparticles. We took advantage of natural affinity between gold and thiol moieties, which were modified to bind DNA fragment. Finally we enclosed doxorubicin into fullerene cages. Doxorubicin intercalated in DNA fragment bound on the particles and thus we were able to connect these parts together. Because GFP behaved as a donor and doxorubicin as an acceptor using excitation wavelength for GFP (395 nm) in emission wavelength of doxorubicin (590 nm) FRET was observed. This nanoconstruction may serve as a double‐labeled transporter of doxorubicin guided by force of external magnetic force owing to the presence of nanomaghemite. Further nanomaghemite offers the possibility of using this technology for thermotherapy.     

Epoxide–quinone transformations: Multi-parametric indicators for assessing animal welfare

The use of a novel epoxide label system as the basis of a new approach to monitoring thiol species relevant to animal welfare contexts is presented. The need for the development of on-site/field testing is demonstrated through the analysis of equine saliva before and after exercise and the implication of delays in the analysis process exposed. The system is selective for thiols and, in contrast to simpler labelling systems, could offer potential for speciation studies.     

Ceric ammonium nitrate (CAN) as a green and highly efficient promoter for the 1,4-addition of thiols and benzeneselenol to α,β-unsaturated ketones

A mild and efficient process for the 1,4-addition of thiols and benzeneselenols to various α,β-unsaturated ketones using a catalytic amount of CAN with excellent product yields is described. This inexpensive, nontoxic, and readily available catalytic ceric(IV) ammonium nitrate system efficiently catalyzes conjugate addition reactions between thiol derivatives and various α,β-unsaturated ketones under solvent-free conditions. A plausible mechanism for the role of CAN, both as a promoter in free radical chain addition reactions as well as a catalyst for the conjugate addition process is proposed.     

Indium(III) chloride-catalyzed thiolysis of meso-aziridines

Indium(III) chloride efficiently catalyzed the thiol addition to meso-aziridines at very low substrate-catalyst ratios giving rise to 1,2-amino sulfides in excellent yields and complete diastereocontrol.     

Thermal expansion of a polydiacetylene single crystal

Summary Fractural length changes l/l of a polydiacetylene (toluene sulfonate) single crystal and its monomer have been measured along the crystallographica-,b-, andc-direction in the temperature range 100 to 400 K. Small steps in the temperature dependence of l/l at 194 K for the polymer and 159 K for the monomer are assumed to be caused by a well known phase transition. From the volume coefficient of thermal expansion the bulk Grüneisenparameter _b has been calculated. Temperature dependence as well as absolute values of _b for the polymer crystal are found to be in accordance with current theories assuming that both inter and intrachain vibrations strongly influence the thermoelastic behaviour of polymer crystals.

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Zusammenfassung Die relative Längenänderung l/l eines Polydiacetylen (Toluolsulfonat) Einkristalls und des zugehörigen Monomerkristalls wurde entlang der kristallographischena-,b-undc-Richtung im Temperaturbereich 100 bis 400 K gemessen. Kleine Stufen im Temperaturverlauf von l/l bei 194 K für den Polymerkristall und bei 159 K für den Monomerkristall werden als Einfluß einer bekannten Phasenumwandlung gedeutet. Aus dem Volumenausdehnungskoeffizienten wurde der Bulk-Grüneisenparameter _b berechnet. Sowohl die Temperaturabhängigkeit als auch absolute Werte von _b für den Polymerkristall befinden sich in Einklang mit theoretischen Modellen, wenn man annimmt, daß sowohl Inter- als auch Intrakettenschwingungen das thermoelastische Verhalten von Polymerkristallen beeinflussen.

     

Thiol-mediated tandem Michael-aldol reaction: a convenient method for the synthesis of fused cyclopentenones

A simple, convenient, one-pot synthetic approach towards substituted cyclopentenone derivatives via thiol-mediated tandem Michael-aldol reaction followed by acid-catalyzed thiol elimination and isomerization of 3-(2-formyl-3,4-dihydronapthalene 1-yl)-acrylic acid esters has been developed.