Search results for "Nitroxyl"

Interaction between nitroxyl radicals and CdTe quantum dots: Determination of fluorescence-quenching mechanisms in aqueous solution

2019

Abstract The present work characterizes the optical properties of CdTe quantum dots (CdTe QDs) after interaction with nitroxyl radicals based on steady-state and time-resolved fluorescence spectroscopy studies. QDs of different sizes were exposed to 2 different nitroxyl radicals, i.e., TEMPO and 4-amino-TEMPO radicals. A clear dependence of dynamic and static Stern-Volmer constants values, KD and KS, respectively, was observed as a function of the size of QDs used, with a change from a mostly static mechanism (for smaller QD sizes) to a dynamic mechanism predominating as the nanoparticles increase in size. All observed effects are dependent on both the concentration of the radical and the s…

Waste-free electrochemical oxidation of alchools in water

2006

We describe a new sol-gel molecular electrode made of a thin layer of organosilica doped with the nitroxyl radical TEMPO (2,2,6,6-tetrame-thylpiperidine-1-oxyl) electrodeposited on the surface of an ITO-coated glass and its employment as a selective and versatile oxidation catalyst in the electrochemical conversion of different alcohols to carbonyl compounds. Environmentally friendly water or a water/acetonitrile mixture buffered with bicarbonate is used as solvent. The electrode is highly stable and it can be reused for a prolonged period of time allowing easy separation from the products.

Structural insight on organosilica electrodes for waste-free alcohol oxidations

2007

Organic modification of sol-gel catalytic glassy electrodes made of a thin layer of organosilica doped with nitroxyl radical TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) crucially enhances stability in the waste-free oxidation of alcohols to carbonyls in water. Structural comparison between analogous films made of organosilica and unmodified SiO2 shows that the origin of the pronounced stable activity of the ORMOSIL film lies in high hydrophobic and also in the pronounced low degree of hydrophilicity.

Synthesis, structural characterization and electrochemical and magnetic studies of M(hfac)2 (M = CuII, CoII) and Nd(hfac)3 complexes of 4-amino-TEMPO

2020

Three mononuclear complexes [M(hfac)x(ATEMPO)y], where M = Cu (11) and Co (12), x = y = 2; M = Nd (13), x = 4, y = 1, and two polynuclear complexes [{Cu(hfac)2(ATEMPO)}n], where n = 2 (14) and 4 (15), were obtained by the reaction of M(hfac)x (M = CuII, CoII, NdIII; x = 2, 3) with 4-amino-TEMPO (4-amino-2,2,6,6-tetramethylpiperidin-N-oxyl) in good yields and their structural, electrochemical and magnetic properties were examined. In all cases, the radical is coordinated to the metal through the amino group, except 15, and the metal ions have an octahedral geometry, except 13. Different coordination architectures of the copper complexes were obtained as a function of the stoichiometry and so…

Nitroxyl Radical‐Mediated Oxidation of Alcohols in Continuous Microreactors

2019

Endor Determined Structure and Conformation of Spin-Labeled Methyl L-Phenylalanate in Frozen Solutions

1990

The conformation of L-phenylalanine and methyl L-phenylalanate acylated at the amino nitrogen position with the nitroxyl spin-label 2,2,5,5-tetramethyl- l-oxypyrroline-3-carboxylic acid has been determined by ENDOR spectroscopy and computer based molecular modeling. ENDOR spectra of spin-labeled L- phenylalanine and the corresponding methyl ester of L-phenylalanine and of their 8-fluoro and £-fluoro derivatives in perdeuterated methanol or chloroform/toluene exhibited well resolved resonance absorptions from protons and fluorines of the amino acid moiety. From the analysis of the dependence of the ENDOR spectra on Hq, we have identified principal hyperfine coupling (hfc) components of each …