10.1021/ja3083818
The research discusses the interconversion of nitrogen oxides, nitrite (NO2?) and nitric oxide (NO), mediated by a heme/Copper (Cu) assembly, mimicking the active site of cytochrome c oxidase. The study focuses on the role of this assembly in cellular processes, particularly in oxygen sensing and nitric oxide signaling. Experiments involved the reaction of a partially reduced heme/Cu complex with nitrite to produce nitric oxide, with the heme acting as the reductant and CuII ion facilitating the process. Conversely, a μ-oxo heme-FeIII?O?CuII complex was used to oxidize NO back to nitrite. Reactants included the iron(II) complex (F8)FeII and a preformed copper(II)?nitrito complex [(tmpa)CuII(NO2)][B(C6F5)4], with reactions carried out under a nitrogen atmosphere in acetone at room temperature. Analyses used to characterize the products and monitor the reactions included UV?vis, electron paramagnetic resonance (EPR), and IR spectroscopies, as well as capillary electrophoresis for nitrite analysis. The research provides insights into the biological chemistry of nitrogen oxides and the role of heme/Cu assemblies in these redox reactions.
10.1016/S0040-4039(00)96070-2
The research aimed to study the photodecomposition of α-nitratomethylbenzoin using electron spin resonance (ESR) spectroscopy. The purpose of the study was to understand the radical formation and behavior when α-nitratomethylbenzoin was irradiated in aromatic solvents. The researchers observed the formation of a single radical, identified as benzoyl benzoylmethyl nitroxide, which they hypothesized was formed through the trapping of both a benzoyl and a benzoylmethyl radical by nitric oxide. The study concluded that, in addition to the expected α-cleavage, an O-NO2 bond cleavage must have occurred, leading to the formation of the observed nitroxide. The chemicals used in this process included α-nitratomethylbenzoin, benzene as the solvent, and nitric oxide as a spin trapping agent. The researchers also mentioned the use of sulphonic and carboxylic esters of α-hydroxymethylbenzoin in their comparative analysis.
10.1021/ma021292m
The research focuses on the synthesis, kinetic, and stability studies of dendrimeric-containing nitronyl nitroxides as spin traps for nitric oxide (NO?). The purpose of this study was to develop a family of dendrimers that could effectively trap NO?, a free radical with a long lifetime in biological environments, and to overcome the limitations of traditional spin traps, such as iron chelates, which are unstable in biological milieus. The researchers synthesized a series of dendrimers with terminal nitronyl nitroxide groups and evaluated their reaction rates with NO?, their spin-trapping capacity, and their stability under various experimental conditions. The key chemicals used in the synthesis process included 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline 3-oxide, N-hydroxysuccinimide, 1,3-dicyclohexylcarbodiimide, and various dendrimers like poly(propyleneimine tetraamine) dendrimers (DAB-Am).
10.1021/jo800367r
The study presents a concise and efficient total synthesis of biologically interesting natural products mallotophilippens C and E. Mallotophilippens C and E are pyranochalcones isolated from Mallotus philippinensis, known for their potential in inhibiting nitric oxide production and other biological activities, making them promising candidates for new drug development. The key strategies in the synthesis involve ethylenediamine diacetate-catalyzed benzopyran formation reactions and base-catalyzed aldol reactions. The synthesis of mallotophilippen C starts from 2,4,6-trihydroxyacetophenone (4), which undergoes a series of reactions including geranylation, cyclization, methoxymethylation, and condensation to form the final product. Similarly, mallotophilippen E is synthesized from 2,4,6-trihydroxyacetophenone (4) through prenylation, cyclization, protection, and condensation steps. The synthetic routes are concise, involving only five steps, and provide a more efficient method compared to previous approaches. The synthesized compounds' spectral data match those reported in the literature, confirming their structures.
10.1016/j.molstruc.2005.01.038
The research investigates the synthesis, spectroscopic characterization, and X-ray structure of two rhenium complexes: [ReBr3(MeCN)(dppe)] (1) and [ReBr3(NO)(dppe)]0.57[ReOBr3(dppe)]0.43 (2). The study begins with the preparation of complex 1 through the reaction of [ReOBr3(dppe)] with acetonitrile in the presence of excess triphenylphosphine. This complex then reacts with gaseous nitric oxide to form the mixed complex 2, which contains rhenium atoms in both +2 and +5 oxidation states. The researchers used various techniques, including UV–vis spectroscopy, IR spectroscopy, and magnetic susceptibility measurements, to characterize the complexes. They also employed density functional theory (DFT) and time-dependent DFT (TDDFT) calculations to optimize the geometries and calculate the electronic transitions of the complexes. The study provides valuable insights into the reactivity of rhenium complexes with nitric oxide and the electronic structure of the resulting compounds.
10.1021/jp962686g
The research investigates the reactions of the cyanomethylene (HCCN) radical with nitric oxide (NO) and molecular oxygen (O2) at 298 K using infrared kinetic spectroscopy. The study determines the overall second-order rate constants for these reactions as (3.5 ± 0.6) × 10^-11 cm3 molecule^-1 s^-1 for HCCN + NO and (1.8 ± 0.4) × 10^-12 cm3 molecule^-1 s^-1 for HCCN + O2. For the reaction with NO, hydrogen cyanide (HCN) and fulminic acid (HCNO) were observed as products, while for the reaction with O2, HCN, hydrogen isocyanide (HNC), and carbon dioxide (CO2) were identified. The study also searched for but did not detect several other potential products, including isocyanic acid (HNCO), cyanic acid (HOCN), formyl radical (HCO), isofulminic acid (HONC), hydroxyl radical (OH), and ethynyl radical (C2H). The research concludes that the observed products are likely formed through secondary processes rather than directly from the reactions of HCCN with NO or O2.
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