Abnormally enhanced Eu emission in Y2O2SO4:Eu inherited from their precursory dodecylsulfate-templated concentric-layered nanostructure

A new nanostructure-mediated approach was demonstrated to synthesize Eu³⁺-doped yttrium oxysulfates Y₂O₂SO₄:Eu³⁺ giving rise to abnormally enhanced Eu³⁺ emission. Yttrium and europium salts, sodium dodecylsulfate (SDS), and urea at various Eu³⁺ concentrations were reacted in aqueous solution at 80, 85, and 87 °C to yield Eu³⁺-doped dodecylsulfate-templated yttrium oxide mesophases with straight-layered (S-type), concentric-layered (C-type) and layer-to-hexagonal transient-layered (T-type) structures, respectively. On calcination at 1000 °C, all of these mesophases were converted into Y₂O₂SO₄:Eu³⁺ to exhibit luminescence bands including the ⁵D₀-⁷F₂ transition with a tendency in intensity to saturate or reach a maximum at 10-12 mol% Eu doping. The Eu³⁺ emissions for Y₂O₂SO₄:Eu³⁺ mediated by the T- and C-type mesophases were enhanced in intensity by a factor of about two and three times, respectively, stronger than those for not only compositionally the same sulfate Y₂O₂SO₄:Eu³⁺ obtained from yttrium-based sulfates but also Y₂O₃:Eu³⁺ obtained in the SDS-free system. In contrast, the emission intensities for the S-type-mesophase-mediated Y₂O₂SO₄:Eu³⁺ were close to those for the latter sulfates. The abnormally enhanced emission is likely based on specific deformation of sulfate groups induced through the conversion of concentric dodecylsulfate-layers to straight sulfate-layers in the oxysulfate framework upon calcination.     

Development of a Versatile Protein Labeling Tool for Live-Cell Imaging Using Fluorescent β-Lactamase Inhibitors

To understand the function of protein in live cells, real-time monitoring of protein dynamics and sensing of their surrounding environment are important methods. Fluorescent labeling tools are thus needed that possess fast labeling kinetics, high efficiency, and long-term stability. We developed a versatile chemical protein-labeling tool based on fluorophore-conjugated diazabicyclooctane β-lactamase inhibitors (BLIs) and wild-type TEM-1 β-lactamase protein tag. The fluorescent probes efficiently formed a stable carbamoylated complex with β-lactamase, and the labeled proteins were visualized over a long period of time in live cells. Moreover, use of an α-fluorinated carboxylate ester-based BLI prodrug enabled the probe to permeate cell membranes and stably label intracellular proteins after unexpected spontaneous ester hydrolysis. Lastly, combining the labeling tool with a pH-activatable fluorescent probe allowed visual monitoring of lysosomal protein translocation during autophagy.     

Intramolecular ring opening of a 2,3-epoxy alcohol by a xanthate anionic center; stereospecific preparation of 2-mercapto-1,3-diol units

Stereospecific ring openings of optically active 2,3-epoxy alcohols were performed by the reaction of 1 , 3 , 5 , and 7 with carbon disulfide and sodium hydride to give the five-membered xanthates 2 , 4 , 6 , and 8 . Both enantiomers of 2-mercapto-1,3-diol triacetates, 11 and 14 , were derived from 4 and 6 , respectively. The ring opening reaction proceeded at −78°C to −30°C, and the yields were around 80%. However, at a higher temperature between 0°C to room temperature, a complicated reaction took place and led to the formation of two isomers of the cyclic thiol carbonates 15 and 16 from 1 or 5 . These processes were also stereospecific, and mechanisms have been proposed. In the case of the 3,4-epoxy alcohol 20 , the epoxide ring opening gave the six-membered xanthate 21 stereospecifically.