Wesley R Browne

Publications (125) View all

• Article: Photo-induced oxidation of [FeII(N4Py)CH3CN] and related complexes

  Apparao Draksharapu, Qian Li, Gerard Roelfes, Wesley Browne
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  ABSTRACT: The photochemistry of the complexes [Fe(N4Py)(CH3CN)](ClO4)2 (1) , where 5 N4Py is 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine and [Fe(MeN4Py)(CH3CN)](ClO4)2 (2), where MeN4Py 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)ethanamine, in water, dichloromethane and methanol, is described. Under UV or visible irradiation both 1 and 2 undergo enhancement of the rate of outer sphere electron transfer to 3O2 to yield the superoxide radical anion and the complexes in the Fe(III) redox state. 10 Addition of ascorbic acid to the photoproduct leads to a recovery of the initial UV/Vis spectrum of 1 and 2, indicating that ligand oxidation does not occur. The results are discussed within the context of the recent report of the enhancement of the oxidative DNA cleavage activity of 1 under UV and visible irradiation (Inorg. Chem. 2010, 49, 11009).
  Dalton Transactions 03/2012; · 3.84 Impact Factor
• Article: Off-line reaction monitoring of the oxidation of alkenes in water using drop coating deposition Raman (DCDR) spectroscopy.

  Shaghayegh Abdolahzadeh, Nicola M Boyle, Apparao Draksharapu, Andrew C Dennis, Ronald Hage, Johannes W de Boer, Wesley R Browne
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  ABSTRACT: The application of drop coating deposition Raman (DCDR) spectroscopy to the field of reaction progress monitoring is addressed in this contribution. Although, DCDR spectroscopy has seen recent application in the study of biological fluids, its application in other areas has not yet been explored. Here we apply the technique to the catalysed oxidation of alkenes to epoxides in aqueous solutions at concentrations <10 mM. The effect of surface characteristics, background interferences, homogeneity of distribution of analytes, drying time, as well as instrumental limits of detection and calibration are discussed. We demonstrate that reproducible spectra can be obtained routinely, with relatively little variance, with short acquisition times and samples volumes of 2-10 μl and as little as 1 μg of analyte. The utility of the technique compared with online reaction monitoring by (1)H NMR and Raman spectroscopy is demonstrated in the excellent correlation between data obtained off and on-line.
  The Analyst 04/2013; · 4.23 Impact Factor
• Article: Palladium-Catalyzed Selective Anti-Markovnikov Oxidation of Allylic Esters.

  Jia Jia Dong, Martín Fañanás-Mastral, Paul L Alsters, Wesley R Browne, Ben L Feringa
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  ABSTRACT: An aldol alternative: The palladium(II)-catalyzed anti-Markovnikov oxidation of allylic esters to aldehydes at room temperature provides a viable alternative to valuable cross aldol products. High regioselectivity towards the aldehyde product was achieved using the ester protecting group for the allylic alcohol. Rapid isomerization and the much higher rate of oxidation of the branched isomer result in the same product forming from both linear and branched allylic esters.
  Angewandte Chemie International Edition 04/2013; · 13.45 Impact Factor
• Article: Photo-induced oxidation of [Fe(II)(N4Py)CH(3)CN] and related complexes.

  Apparao Draksharapu, Qian Li, Gerard Roelfes, Wesley R Browne
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  ABSTRACT: The photochemistry of the complexes [Fe(N4Py)(CH(3)CN)](ClO(4))(2) (), where N4Py is 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)methanamine and [Fe(MeN4Py)(CH(3)CN)](ClO(4))(2) (), where MeN4Py is 1,1-di(pyridin-2-yl)-N,N-bis(pyridin-2-ylmethyl)ethanamine, in water, dichloromethane and methanol is described. Under UV or visible irradiation both and undergo enhancement of the rate of outer sphere electron transfer to (3)O(2) to yield the superoxide radical anion and the complexes in the Fe(iii) redox state. Addition of ascorbic acid to the photoproduct leads to a recovery of the initial UV/Vis spectrum of and , indicating that ligand oxidation does not occur. The results are discussed within the context of the recent report of the enhancement of the oxidative DNA cleavage activity of under UV and visible irradiation (Inorg. Chem. 2010, 49, 11009).
  Dalton Transactions 09/2012; 41(42):13180-90. · 3.84 Impact Factor
• Source

  Available from: Bin Mao

  Article: Oxidation of Alkenes with H2O2 by an in-Situ Prepared Mn(II)/Pyridine-2-carboxylic Acid Catalyst and the Role of Ketones in Activating H2O2

  Jia Jia Dong, Pattama Saisaha, Tim G. Meinds, Paul L. Alsters, Edwin G. Ijpeij, Ruben P. van Summeren, Bin Mao, Martín Fañanás-Mastral, Johannes W. de Boer, Ronald Hage, Ben L. Feringa, Wesley R. Browne
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  ABSTRACT: doi: 10.1021/cs3002226
  ACS Catalysis 04/2012; 2(6):1087-1096.