title: How Anionic Vesicles Steer the Oligomerization of Enzymatically Oxidized p-Aminodiphenylamine (PADPA) toward a Polyaniline Emeraldine Salt (PANI-ES)-Type Product.
abstract: The oxidation of the aniline dimer, p-aminodiphenylamine (PADPA), with Trametes versicolor laccase and O2 in an aqueous solution of pH 3.5 is controlled by negatively charged AOT (sodium bis(2-ethylhexyl) sulfosuccinate) vesicles. With vesicles, a product resembling polyaniline in its emeraldine salt form (PANI-ES) is obtained, in contrast to the reaction without vesicles where no such product is formed. To understand this observation, the product distribution and structures from the reaction with and without vesicles were determined by using partially selectively deuterated PADPA as a starting material and analyzing the products with HPLC-MS. We found that in the presence of vesicles the main product is obtained in about 50% yield, which is the N-C-para-coupled PADPA dimer that has spectroscopic properties of PANI-ES, as determined by time-dependent density functional theory (TD-DFT) calculations. A secondary reaction route leads to longer PADPA oligomers that must contain a phenazine core. Without vesicles, PADPA and its products undergo partial hydrolysis, but in the presence of vesicles, hydrolysis does not occur. Because molecular dynamics (MD) simulations show that the main intermediate oxidation product is embedded within the vesicle membrane, where the water content is very low, we propose that the microenvironment of the vesicle membrane protects the oxidation products from unwanted hydrolysis.
authors: Laboratory of Polymer Chemistry, Department of Materials, ETH Zürich , Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland.
authors: Sandra
authors: S
authors: Luginbühl
authors: Laboratory of Organic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich , Vladimir-Prelog-Weg 3, 8093 Zürich, Switzerland.
authors: Louis
authors: L
authors: Bertschi
authors: Materials Science Education, Department of Materials, ETH Zürich , Leopold-Ruzicka-Weg 4, 8093 Zürich, Switzerland.
authors: Martin
authors: M
authors: Willeke
authors: xirrus GmbH, Buchzelgstrasse 36, 8053 Zürich, Switzerland.
authors: Lukas D
authors: LD
authors: Schuler
authors: Laboratory of Polymer Chemistry, Department of Materials, ETH Zürich , Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland.
authors: Peter
authors: P
authors: Walde
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D000838:Anions; D001704:Biopolymers / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D056004:Molecular Dynamics Simulation; D012492:Salts / Q000737:chemistry; D013057:Spectrum Analysis / Q000379:methods; D015091:beta-Alanine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D000814:Aniline Compounds; D000838:Anions; D001704:Biopolymers; D012492:Salts; C416807:polyaniline; D015091:beta-Alanine; C072992:N(3)-(bromoacetyl)-2,3-diaminopropanoic acid