How experimental details matter. The case of a laccase-catalysed oligomerisation reaction

Abstract

A laccase-catalysed oligomerisation of p-aminodiphenylamine was investigated in an aqueous medium containing 80–100 nm-sized anionic vesicles formed from AOT, the sodium salt of bis(2-ethylhexyl)sulfosuccinic acid.

Effect of Template Type on the Trametes versicolor Laccase-Catalyzed Oligomerization of the Aniline Dimer p-Aminodiphenylamine (PADPA)

“…These are the conditions that we found to be ideal for a reproducible reaction with 100 nm sized AOT vesicles at an AOT concentration of 1.5 mM. 22…”

Synthesizing Polyaniline With Laccase/O2 as Catalyst

“…Applications of laccase-catalyzed in vitro reactions include the laccase/O 2 -mediated syntheses of polymeric (or oligomeric) products from methyl methacrylate or styrene (with acetylacetone as mediator, see Tsujimoto et al, 2001), acrylamide (Ikeda et al, 1998), phenols (Mita et al, 2003; Marjasvaara et al, 2006; Sun et al, 2013; Su et al, 2018a, 2019a), pyrrole (Song and Palmore, 2005; Junker et al, 2015), dopamine (Tan et al, 2010; Li et al, 2018), 3,4-ethylenedioxythiophene (Shumakovich et al, 2012b; Vasil'eva et al, 2018), or various arylamines (Ćirić-Marjanović et al, 2017; Zhang T. et al, 2018; Su et al, 2019a,b). With respect to the latter type of monomers, the focus often was—and still is—on the synthesis of oligo- or polyaniline (PANI) from aniline (Karamyshev et al, 2003; Vasil'eva et al, 2007, 2009; Streltsov et al, 2008, 2009; Shumakovich et al, 2010, 2012a, 2014; Leppänen et al, 2013; Zhang et al, 2014, 2016; Zhang Y. et al, 2018; Junker et al, 2014a; de Salas et al, 2016; Su et al, 2018b) or from p -aminodiphenylamine (PADPA), the linear para N-C-coupled aniline dimer Shumakovich et al, 2011; Junker et al, 2014b; Janoševic Ležaić et al, 2016; Luginbühl et al, 2016; Kashima et al, 2018;Kashima et al, 2019).…”

“…The obtained product mixture can be separated by high performance liquid chromatography (HPLC) with UV/vis diode array or mass spectrometry detection. This is at least the case for the products obtained from the Trametes versicolor laccase/O 2 -catalyzed oxidation of PADPA at pH = 3.5 in the presence (or absence) of AOT vesicles as templates (Junker et al, 2014b; Luginbühl et al, 2016; Kashima et al, 2018). Reaction product extraction into an organic solvent ( t -butylmethylether) and analysis are possible for the specific reaction conditions used.…”

“…After the entire product separation and identification of the molecules present, information on original protonation and oxidation states is lost. Only through the combination of the HPLC analysis—which was also carried out with partially deuterated PADPA monomers and H218O—and complementary in situ UV/vis/NIR, EPR and Raman spectroscopy measurements of the entire reaction mixture recorded during the reaction and after reaching reaction equilibrium, clear conclusions about the effect of the AOT vesicle template on the outcome of the reaction could be drawn (Luginbühl et al, 2016; Kashima et al, 2018). Three essential findings are worth mentioning.…”

“…(i) The main product of the reaction in the presence of the vesicles is the para -N-C-coupled PADPA dimer in its half-oxidized, protonated state, i.e., the tetraaniline repeating unit of ideal PANI-ES (Figure 2A). This is the shortest possible PANI-ES type molecule and contributes most substantially among all formed products to the in situ recorded absorption spectrum of the reaction mixture, with λ max ≈ 1,070 and ≈ 430 nm (Junker et al, 2014b; Kashima et al, 2018; Figure 2C), the in situ recorded EPR spectrum (Janoševic Ležaić et al, 2016; Kashima et al, 2018), and the in situ recorded Raman spectrum with characteristic band positions at ν ≈ 1,350–1,380 cm −1 (Janoševic Ležaić et al, 2016; Kashima et al, 2018; Figure 2D). Higher PANI-ES-type oligomers are also formed but to a much lesser extent.…”