Ammonium Pertechnetate in Mixtures of Trifluoromethanesulfonic Acid and Trifluoromethanesulfonic Anhydride

Ammonium pertechnetate reacts in mixtures of trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid under final formation of ammonium pentakis(trifluoromethanesulfonato)oxidotechnetate(V), (NH$_{4}$)$_{2}$ [TcO(OTf) $_{5}$]. The reaction proceeds only at exact concentrations and under the exclusion of air and moisture via pertechnetyl trifluoromethanesulfonate, [TcO$_{3}$(OTf)], and intermediate Tc$^{VI}$ species. $^{99}$Tc nuclear magnetic resonance (NMR) has been used to study the Tc$^{VII}$ compound and electron paramagnetic resonance (EPR), $^{99}$Tc NMR and X-ray absorption near-edge structure (XANES) experiments indicate the presence of the reduced technetium species. In moist air, (NH$_{4}$)2[TcO(OTf)5] slowly hydrolyses under formation of the tetrameric oxidotechnetate(V) (NH$_{4}$)$_{4}$ [{TcO(TcO$_{4}$)$_{4}$}$_{4}$] ⋅10 H$_{2}$O. Single-crystal X-ray crystallography was used to determine the solid-state structures. Additionally, UV/Vis absorption and IR spectra as well as quantum chemical calculations confirm the identity of the species

Hydrothermal Synthesis, Microstructure and Photoluminescence of Eu3+-Doped Mixed Rare Earth Nano-Orthophosphates

Eu3+-doped mixed rare earth orthophosphates (rare earth = La, Y, Gd) have been prepared by hydrothermal technology, whose crystal phase and microstructure both vary with the molar ratio of the mixed rare earth ions. For LaxY1–xPO4: Eu3+, the ion radius distinction between the La3+ and Y3+ is so large that only La0.9Y0.1PO4: Eu3+ shows the pure monoclinic phase. For LaxGd1–xPO4: Eu3+ system, with the increase in the La content, the crystal phase structure of the product changes from the hexagonal phase to the monoclinic phase and the microstructure of them changes from the nanorods to nanowires. Similarly, YxGd1–xPO4: Eu3+, Y0.1Gd0.9PO4: Eu3+ and Y0.5Gd0.5PO4: Eu3+ samples present the pure hexagonal phase and nanorods microstructure, while Y0.9Gd0.1PO4: Eu3+ exhibits the tetragonal phase and nanocubic micromorphology. The photoluminescence behaviors of Eu3+ in these hosts are strongly related to the nature of the host (composition, crystal phase and microstructure)

Potentiation of the activation of cholinergic receptors by multivalent presentation of ligands supported on gold nanoparticles

Gold nanoparticles (NP) with a functionalized ligand shell offer the possibility to potentiate the action of agonists at the receptor site by multivalency. In order to find out whether this can be realized for the pharmacologically important class of cholinergic receptors known to be involved in the regulation of most organ functions, carbachol-functionalized gold NPs (Au-MUDA-CCh) with an average diameter of 14 nm were synthesized. As functional read-out, cholinergic agonist-induced anion secretion was measured as increase in short-circuit current (I-sc) across rat proximal colon in Ussing chambers. Similarly to the corresponding native agonist acetylcholine, Au-MUDA-CCh induced a concentration-dependent increase in I-sc, which represents chloride secretion across the epithelium. This response was inhibited by atropine and hexamethonium indicating the activation of muscarinic and nicotinic receptors by the functionalized NPs. A strong potentiation of ligand-receptor interaction was a key benefit of functionalized NPs over native agonists. This was observed with physiological approaches as measurements of changes in I-sc revealed a nearly equivalent response evoked by 1 pM Au-MUDA-CCh and 500 nM native CCh. To better determine this potentiation at the receptor level, pharmacological approaches based on the signaling cascade of ACh-induced activation of muscarinic receptors were used. FRET (Forster Resonance Energy Transfer) measurements performed on HEK293T cells transiently transfected with M-3-R, G(q)-YFP, G(1)-wt and CFP-G(2), revealed that both Au-MUDA-CCh and native CCh activated G-proteins with EC50 amounting to 127 +/- 0.44 fM and 224 +/- 7.12 nM, respectively. Thus, the functionalization of the NPs with CCh yields a potentiation by over 10(6), a property that could find usage in specific targeting, activation and compensation of pathologically reduced expression of receptors of interest