On the importance of experimental details for an enzyme-catalyzed oligomerization of p-aminodiphenylamine in the presence of AOT vesicles

摘要

The oxidation of the aniline dimer, p-aminodiphenylamine (PADPA), with Trametes versicolor laccase (TvL) and O_2 was investigated in aqueous solution at pH = 3.5 in the presence of vesicles from sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The vesicles serve as dispersed anionic "templates". Under selected experimental conditions we previously found out, that the reaction yields oligomeric products which resemble the conductive emeraldine salt form of polyaniline (PANI-ES), with high absorption at λ ≈ 1000 nm. The entire reaction mixture is complex. It consisted of (i) an aqueous solution of pH = 3.5 (called "pH=3.5 solution"), (ii) PADPA as monomer, (iii) TvL/O_2 as catalyst/oxidant system, and (iv) 80-100 nm-sized unilamellar AOT vesicles as templates. The AOT concentration was kept constant at 1.5 mM and the concentration of PADPA at the start of the reaction was 1.0 mM, see Fig. 1.