Stabilization of p-Phenylenebis(N-tert-butylaminoxyl) Relative to p-Benzoquinonediimine N,N′-Dioxide

Steric interactions between methoxy and tert -butyl groups are the reason that 2 only exists as p-phenylenebis(N-tert-butylaminoxyl) B . The p-phenylenebis(N-tert-butylaminoxyl) 1 has the p-quinonediimine N,N′-dioxide structure Q in solution as well as in the crystalline state.     

Nitric Oxide: Chemical Puzzles Posed by a Biological Messenger

Recent years have seen a massive growth of interest in the biological effects of nitric oxide (NO): It acts as a signaling molecule in blood vessels and the brain, and as a defense against pathogens in the immune system. Discussed are the chemical events underlying the physiology of this versatile little molecule.     

A Triphenylamine Derivative with Three p-(N-tert-Butyl-N-oxylamino)phenyl Radical Units and Yet a Doublet Ground State

A superexchange interaction through the lone pair of electrons on the central nitrogen atom in 1 is invoked to explain the existence of a doublet ground state; two spins on the aminoxyl radical centers couple antiferromagnetically, and one spin remains intact. This proposal is supported by EPR spectroscopic and magnetic measurements.     

A Dendritic Macrocyclic Organic Polyradical with a Very High Spin of S=10

Designed as a ferromagnetically coupled spin pentamer , the macrocyclic polyradical 1 possesses an average spin of S=10 in the ground state. This is the highest spin quantum number that has yet been measured for an organic molecule. Ar=tBuC₆H₄.     

Two-Dimensional Nitroxide-Based Molecular Magnetic Materials

Manganese(II ) complexes of imidazolyl-substituted chelating nitronylnitroxides are characterized by a stereoselective arrangement of the metal centers and the ligands to give a honeycomblike layer structure (shown on the right). The magnetic properties at high temperature indicate the presence of a ferrimagnetic structure within the layers. At low temperatures, ferromagnetic ordering is observed.     

A novel chromogenic and fluorogenic scaffold for detection of oxidative radicals

Radicals have profound biorelevance and their robust detections are warranted. We have devised a novel “covalent-assembly” type scaffold for sensitive detection of oxidative radicals.     

Triplet halocarbene chemistry: p-nitrophenylchlorocarbene and p-nitrophenylbromocarbene

Reactions of p-nitrophenylchlorocarbene with cumene and of p-nitrophenylbromocarbene with toluene afford C-H abstraction-recombination products that suggest the involvement of triplet arylhalocarbenes.     

Transformations of radicals and ions in irradiated sodium sulfate doped with nitrate ions

The structure and properties of the paramagnetic centers formed by γ-irradiation at 77 K in sodium sulfate doped with nitrate ions have been investigated by the EPR method. The NO^2? ₃, NO₂ and SO^? ₄ radicals have been identified. The orientation of NO^2? ₃ relation to crystallographic axes is determined. In the 77-400 K temperature range the transformations of observable radicals have been studied. The mechanisms of their formation and thermal annealing have been discussed. The symmetry of nitrate ions in sodium sulfate was investigated by diffuse reflectance infrared Fourier transform spectroscopy. At the concentration of NO^? ₃ up to 5.5 × 10¹⁸ g^?1 the nitrate ion was supposed to have a planar or pyramidal configuration of the D_3h or C_3V symmetries. At the concentration of the dopant higher than 5.5 × 10¹⁸ g^?1 the nitrate ions with the C_2V symmetry were observed.     

升麻多糖提取及其抗氧化作用

研究了升麻多糖的提取及其对羟基自由基的清除作用.采用热水浸提及醇沉法从升麻中提取多糖,通过比色法研究其清除羟基自由基的能力.升麻多糖清除能力与多糖浓度有明显的量效关系,清除50％羟基自由基所需要的多糖浓度为2.4mg/mL,结果表明升麻多糖具有良好的清除羟基自由基的能力.     

The BΣ state of the SO radical

Spectra of the B³Σ⁻- X³Σ⁻ transition in SO above the first dissociation limit are recorded using degenerate four wave mixing. These spectra are combined with earlier work involving laser induced fluorescence, absorption spectra and Fourier transform emission spectra, to enable a rotational analysis and deperturbation of vibrational levels of the B state up to v′ = 16. Numerous perturbations were noted within the B³Σ⁻ state, and the origin of these is discussed. In a number of cases, these perturbations can be attributed to interactions with specific other electronic states of SO, such as A³Π, C³Π, d¹Π, and A″ ³Σ⁺.