Microemulsion-controlled Reaction Sites in Biocatalytic Films for Electrochemical Reduction of Vicinal Dibromides.
From: Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269-3060, USA.
Langmuir : the ACS journal of surfaces and colloids
- Publish Date: Dec 2006
- ISSN: 0743-7463
- Volume: 22
- Issue: 25
- Pages: 10788-95
- Medium: Print
- Language: English
- Citation (JAMA): Vaze Abhay, Rusling James F, et al. Microemulsion-controlled Reaction Sites in Biocatalytic Films for Electrochemical Reduction of Vicinal Dibromides.. Dec 2006;22:10788-95
Abstract
We report herein the electrochemical dehalogenation of vicinal dibromides in microemulsions using cross-linked films of the redox protein myoglobin (Mb) and poly-l-lysine (PLL) covalently bonded to carbon electrodes. Catalytic reduction of the dibromides to olefins was more efficient in an SDS microemulsion than in a CTAB microemulsion. SDS shifts the Mb redox potential more negative, but a comparison to Mb-SDS films suggests that the activation free energy of the reduction is controlled by an inner-sphere mechanism. SDS also enters the positively charged Mb-PLL films and preconcentrates the dibromide reactants, enhancing catalytic efficiency in SDS microemulsions. Shifts in formal potential and Soret absorbance bands for Mb-PLL films suggested binding of trans-1,2-dibromocyclohexane in the iron heme distal pocket with little catalysis. Results are consistent with active catalytic reduction sites for reactant bound on the protein surface and less-reactive sites in the distal heme pocket. Preconcentration into catalytic PLL films using SDS incorporated from microemulsions may be a general way to improve catalytic efficiency for nonpolar reactants in microemulsions.
Mesh Headings (Keywords): Alkenes, Binding Sites, Carbon, Catalysis, Cyclohexanes, Electrochemistry, Electrodes, Emulsions, Ethane, Membranes, Artificial, Models, Molecular, Myoglobin, Oxidation-Reduction, Polylysine, Quartz, Structure-Activity Relationship, Surface Properties
Check for Full Text / PubMed Unique Identifier (PMID): 17129061
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