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Diazonium Ions (diazonium + ion)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Encapsulation and Stabilization of Reactive Aromatic Diazonium Ions and the Tropylium Ion Within a Supramolecular Host

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2004
Julia L. Brumaghim
Abstract Supramolecular assemblies with internal cavities are being developed as nanoscale reaction vessels to protect or modify the reactivity of guest species through encapsulation. Diazonium cations and the tropylium cation were examined for their ability to encapsulate in the tetrahedral [Ga4L6]12, supramolecular assembly. The 4-(diethylamino)benzenediazonium cation 1 readily formed a 1:1 host,guest complex with this assembly, and this encapsulation prevented 1 from reacting with 2,4-pentanedione in D2O. The tropylium cation also formed a 1:1 host,guest complex with the [Ga4L6]12, assembly, greatly slowing its decomposition in D2O. Encapsulation in the protected environment of this host cavity alters the reactivity of these guest molecules, giving them greater stability. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Palladium,Imidazolium-Catalyzed Carbonylative Coupling of Aryl Diazonium Ions and Aryl Boronic Acids.

CHEMINFORM, Issue 7 2003
Merritt B. Andrus
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Activation barriers for DNA alkylation by carcinogenic methane diazonium ions

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 3 2006
Kaushalya S. Ekanayake
Abstract Methylation reactions of the DNA bases with the methane diazonium ion, which is the reactive intermediate formed from several carcinogenic methylating agents, were examined. The SN2 transition states of the methylation reactions at N7, N3, and O6 of guanine; N7, N3, and N1 of adenine; N3 and O2 of cytosine; and O2 and O4 of thymine were calculated using the B3LYP density functional method. Solvation effects were examined using the conductor-like polarizable continuum method and the combined discrete/SCRF method. The transition states for reactions at guanine N3, adenine N7, and adenine N1 are influenced by steric interactions between the methane diazonium ion and exocyclic amino groups. Both in the gas phase and in aqueous solution, the methylation reactions at N atoms have transition states that are looser, and generally occur earlier along the reaction pathways than reactions at O atoms. The forming bonds in the transition states in water are 0.03 to 0.13 Å shorter than those observed in the gas phase, and the activation energies are 13 to 35 kcal/mol higher. The combined discrete/SCRF solvation energy calculations using base-water complexes with three water molecules yield base solvation energies that are larger than those obtained from the CPCM continuum method, especially for cytosine. Reactivities calculated using barriers obtained with the discrete/SCRF method are consistent with the experimentally observed high reactivity at N7 of guanine. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 277,286, 2006 [source]

Inhibition of acid-induced decomposition of diphenyltriazenes by complexation with cyclodextrins

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2010
Tingting Xu
Acid-promoted NN bond 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 (a microsolvent effect). Association equilibrium constants for 1:1 host,guest complexes increase in the order ,-CD <,-CD , permethyl-,-CD < hydroxypropyl-,-CD, with values for X = 4-OCH3 being larger than those for X = H. In the case of ,-CD, formation of 2:1 host,guest complexes is also involved. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 567,574, 2010 [source]

Activation barriers for DNA alkylation by carcinogenic methane diazonium ions

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 3 2006
Kaushalya S. Ekanayake
Abstract Methylation reactions of the DNA bases with the methane diazonium ion, which is the reactive intermediate formed from several carcinogenic methylating agents, were examined. The SN2 transition states of the methylation reactions at N7, N3, and O6 of guanine; N7, N3, and N1 of adenine; N3 and O2 of cytosine; and O2 and O4 of thymine were calculated using the B3LYP density functional method. Solvation effects were examined using the conductor-like polarizable continuum method and the combined discrete/SCRF method. The transition states for reactions at guanine N3, adenine N7, and adenine N1 are influenced by steric interactions between the methane diazonium ion and exocyclic amino groups. Both in the gas phase and in aqueous solution, the methylation reactions at N atoms have transition states that are looser, and generally occur earlier along the reaction pathways than reactions at O atoms. The forming bonds in the transition states in water are 0.03 to 0.13 Å shorter than those observed in the gas phase, and the activation energies are 13 to 35 kcal/mol higher. The combined discrete/SCRF solvation energy calculations using base-water complexes with three water molecules yield base solvation energies that are larger than those obtained from the CPCM continuum method, especially for cytosine. Reactivities calculated using barriers obtained with the discrete/SCRF method are consistent with the experimentally observed high reactivity at N7 of guanine. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 277,286, 2006 [source]