2684-02-8Relevant articles and documents
Diazotisations in Highly Concentrated Mineral Acids: The Nitrosation Mechanism of Anilinium and Hydroxylammonium Ions through Proton Loss from the Ammonio Group
Zollinger, Heinrich
, p. 1661 - 1664 (1988)
It is shown that the acidity dependence of the rate of nitrosation of aromatic amines and of hydroxylamine in strongly acidic aqueous solutions does not necessarily involve the rearrangement of a charge transfer complex (consisting of the NO+ ion and the substrate with an NH3+ group) in concert with a proton loss at the NH3+ group.More likely, proton loss of the charge complex preceeds the ? -> N rearrangement of the NO+ ion.
New tridentate azo-azomethines and their copper(II) complexes: Synthesis, solvent effect on tautomerism, electrochemical and biological studies
Sarigul, Munire,Deveci, Pervin,Kose, Muhammet,Arslan, Ugur,Türk Dagi, Hatice,Kurtoglu, Mukerrem
, p. 64 - 73 (2015)
In this study, three azo-azomethines and their copper(II) complexes were prepared and characterized by analytical and spectroscopic methods. The complexes prepared were found to be mononuclear and the chelation of the ligands to the copper(II) ions occurs
Swift photoswitching in a binuclear Zn(ii) metallacycle relative to a salen-type ligand
Kumar, Amit,Pandey, Rampal,Gupta, Rakesh Kumar,Mishra, Veenu,Mobin, Shaikh M.,Pandey, Daya Shankar
, p. 6365 - 6376 (2014/04/17)
The synthesis, characterization and photoswitching behavior of a new salen type Schiff base N,N′-bis(2-hydroxy-5-phenylazobenzilidene)-2,4,6- trimethylbenzene-1,3-diamine (H2L) and a binuclear zinc(ii) metallacycle [{Zn(L)}2·2H2O] (1) have been described. Both H2L and 1 have been characterized by satisfactory elemental analyses, spectral (FT-IR, 1H, 13C NMR, ESI-MS, electronic absorption, emission) and electrochemical studies. Crystal structures of both H2L and 1 have been authenticated by single crystal X-ray diffraction analyses. These exhibit trans-cis photoisomerization upon exposure to UV light (365 nm) and get back to a more stable trans-form after withdrawal of the light. Electronic absorption, emission, 1H NMR and cyclic voltammetric studies revealed that trans-cis isomerization in metallacycle 1 is rather rapid (～5.0 s) relative to H2L (～25 s) which has been supported by theoretical studies (DFT). Relatively fast photoisomerization in 1 compared to H2L is facilitated by a small energy gap between HOMO levels of the trans- and cis-isomers. The percentage trans-cis conversion ratio for both H2L and 1 has been evaluated (55-45, H2L; 60-40%, 1) by 1H NMR studies. This journal is the Partner Organisations 2014.
Modifying a known gelator scaffold for nitrite detection
Zurcher, Danielle M.,Adhia, Yash J.,Romero, Julian Diaz,McNeil, Anne J.
supporting information, p. 7813 - 7816 (2014/07/08)
The process of selecting and modifying a known gelator scaffold to develop a new nitrite-based sensor is described. Five new azo-sulfonate gelators were discovered and characterized. The most promising scaffold exhibits a stable diazonium intermediate, proceeds in a high yield, and gels nitrite-spiked tap, river, and pond water. This journal is the Partner Organisations 2014.
Inhibition of Acid-induced decomposition of diphenyltriazenes by complexation with cyclodextrins
Xu, Tingting,Asadi, Atefeh Vaez-Zadeh,Barra, Monica
supporting information; experimental part, p. 567 - 574 (2011/04/26)
Acid-promotedN Nbond cleavage in 1,3-diphenyltriazenes (X-Ph-N=N-NH-Ph-X X = H, 4-OCH3), leading to formation of diazonium ions and anilines, is strongly inhibited in aqueous solutions in the presence of cyclodextrins (CDs). The inhibition is ascribed to the formation of inclusion complexes that render the guest diphenyltriazene significantly less basic as a result of the less polar nature of the CD cavity (amicrosolvent effect). Association equilibrium constants for 1:1 host-guest complexes increase in the order α-CD 3 being larger than those for X = H. In the case of α-CD, formation of 2:1 host-guest complexes is also involved.
Generation and reactivity of the phenyl cation in cryogenic argon matrices: Monitoring the reactions with nitrogen and carbon monoxide directly by IR spectroscopy
Winkler, Michael,Sander, Wolfram
, p. 6357 - 6367 (2007/10/03)
The phenyl cation 1 has been prepared by co-deposition of iodobenzene 6 or bromobenzene 7 with a microwave-induced argon plasma and characterized by IR spectroscopy in cryogenic argon matrices. The cation can clearly be identified by its strongest absorpt
Mechanism of acid-catalysed decomposition of 3-alkyl-1,3-diphenyltriazenes by trichloroacetic acid in hexane
Pytela, Oldrich,Bednar, Roman,Kavalek, Jaromir
, p. 343 - 349 (2007/10/03)
Eight 3-alkyl-1,3-diaryltriazenes with methyl, ethyl, propyl, butyl, pentyl, isopropyl, sec-butyl and cyclohexyl substituents were synthesized and their rate constants of decomposition by trichloroacetic acid (0.01-0.25 mol dm-3) in hexane at 25°C were measured. The kinetic model and mechanism thereof were studied by modelling of the dependences of k obs on the concentration of trichloracetic acid. On the basis of this kinetic model and the interpretation of solvent effects, a reaction mechanism was suggested according to which the triazene reacts with monomer and obviously also opens the dimer of trichloroacetic acid in a single reaction step. At the same time, a non-reactive associate between the N1 nitrogen of triazene and two molecules of trichloroacetic acid is formed in the reaction mixture. The equilibrium and rate constants depend on the addition of trichloroacetic acid as the co-solvent. Copyright
Substituent effects on the thermal cis-to-trans isomerization of 1,3-diphenyltriazenes in aqueous solution
Chen, Nan,Barra, Monica,Lee, Ivan,Chahal, Navjot
, p. 2271 - 2277 (2007/10/03)
The thermal cis-to-trans isomerization of some symmetrically p,p′-disubstituted 1,3-diphenyltriazenes has been studied by means of laser-flash photolysis techniques. The geometric isomerization is catalyzed by general acids and general bases as a result of acid/base-promoted 1,3-prototropic rearrangements. Acid catalysis becomes more prominent as the electron-donating character of the para substituent increases, while base catalysis becomes more important as the electron-withdrawing character of the para substituent increases. In addition, the rate ascribed to the interconversion of neutral cis rotamers through hindered rotation around the nitrogen-nitrogen single bond is found to decrease as the electron-withdrawing character of the para substituent increases. Rates of interconversion of neutral cis rotamers are also found to decrease with decreasing solvent polarity, which is indicative of the involvement of a polar transition state. On the other hand, kinetic investigations of the acid-catalyzed decomposition of target triazenes are consistent with an A1 mechanism.
Oxidation of xenobiotics by plant microsomes, a reconstituted cytochrome P450 system and peroxidase: A comparative study
Stiborova,Schmeiser,Frei
, p. 353 - 362 (2007/10/03)
The microsomal fraction from tulip bulbs (Tulipa fosteriana, L.) contains cytochrome P450 (CYP3, EC 1.14.14.1) and peroxidase (EC 1.11.1.7.) enzymes catalyzing the NADPH - and hydrogen peroxide - dependent oxidation of the xenobiotic substrates, N-nitrosodimethylamine (NDMA), N- nitrosomethylaniline (NMA), aminopyrine and 1-phenylazo 2-hydroxynaphthalene (Sudan I), respectively. Oxidation of these model xenobiotics has also been assessed in a reconstituted electron-transport chain with a partially purified CYP fraction, phospholipid and isolated tulip NADPH:CYP reductase (EC 1.6.2.4.). Peroxidase isolated from tulip bulbs (isoenzyme C) oxidizes these xenobiotics, too. Values of kinetic parameters (K(m), V(max)), requirements for cofactors (NADPH, hydrogen peroxide), the effect of inhibitors and identification of products formed from the xenobiotics by the microsomal fraction, partially purified CYP and peroxidase C were determined. These data were used to estimate the participation of the CYP preparation and peroxidase C in oxidation of two out of the four studied xenobiotics (NMA, Sudan I) in tulip microsomes. Using such detailed study, we found that the CYP-dependent enzyme system is responsible for the oxidation of these xenobiotics in the microsomal fraction of tulip bulbs. The results demonstrate the progress in resolving the role of plant CYP and peroxidase enzymes in oxidation of xenobiotics. (C) 2000 Elsevier Science Ltd.
Cytochrome P-450 from Tulip Bulbs (Tulipa fosteriana l.) oxidizes an azo dye sudan I (1-Phenylazo-2-Hydroxynaphthalene, solvent yellow 14) in vitro
Stiborova, Marie,Hansikova, Hana
, p. 1689 - 1696 (2007/10/03)
The microsomal fraction from tulip bulbs (Tulipa fosteriana L.) contains cytochrome P-450 enzymes catalyzing the NADPH-dependent oxidation of the xenobiotic substrate, an azo dye Sudan I (1-phenylazo-2-hydroxynaphthalene, Solvent Yellow 14). C-Hydroxy derivatives [1-(4-hydroxyphenylazo)-2-hydroxynaphthalene, 1-phenylazo-2,6-dihydroxynaphthalene, 1-(4-hydroxyphenylazo)-2,6-dihydroxynaphthalene] and the benzenediazonium ion are the products of the Sudan I oxidation. The oxidation of Sudan I has also been assessed in a reconstituted electron-transport chain with the isolated cytochrome P-450, isolated plant NADPH-cytochrome P-450 reductase and phospholipid. The results are discussed from the point of view of the role of cytochromes P-450 in the metabolism of xenobiotics in plants.
