The aniline dimer PADPA (= p-aminodiphenylamine = N-phenyl-1,4-phenylenediamine) was polymerized to poly-(PADPA) at 25 °C with Trametes versicolor laccase (TvL)/O 2 as catalyst and oxidant and in the presence of vesicles formed from sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as templates. In comparison to the previously studied polymerization of aniline with the same type of enzyme−vesicle system, the polymerization of PADPA is much faster, and considerably fewer enzymes are required for complete monomer conversion. Turbidity measurements indicate that PADPA strongly binds to the vesicle surface before oxidation and polymerization are initiated. Such binding is confirmed by molecular dynamics (MD) simulations, supporting the assumption that the reactions which lead to poly(PADPA) are localized on the vesicle surface. The poly(PADPA) obtained resembles the emeraldine salt form of polyaniline (PANI-ES) in its polaron state with a high content of unpaired electrons, as judged from UV/ vis/NIR, EPR, and FTIR absorption measurements. There are, however, also notable spectroscopic differences between PANI-ES and the enzymatically prepared poly(PADPA). Poly(PADPA) appears to be similar to a chemically synthesized poly(PADPA) as obtained in a previous work with ammonium peroxydisulfate (APS) as the oxidant in a mixture of 50 vol % ethanol and 50 vol % 0.2 M sulfuric acid (J. Phys. Chem. B 2008, 112, 6976−6987). ESI-MS measurements of early intermediates of the reaction with TvL and AOT vesicles indicate that the presence of the vesicles decreases the extent of formation of unwanted oxygen-containing species in comparison to the reaction in the absence of vesicles. This is the first information about the differences in the chemical composition of early reaction intermediates when the reaction carried out in the presence of vesicles under optimal conditions is compared with a template-free system.

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.

In order to produce materials with tailored structures and functions via supramolecular self-assembly of molecular precursors in a predictable fashion, it is necessary to develop 'supramolecular methods' based on structurally simple 'supramolecular synthons'. Thus, the formation of one-dimensional aggregates from p-conjugated molecules requires a combination of non-covalent interactions that efficiently suppresses lateral aggregation, promotes one-dimensional aggregation, and is also compatible with a productive p-p overlap of the constituent molecules. In the present work, we demonstrate that oligopeptide-polymer derivatives comprising a flexible polymer segment terminally attached to a b-sheet-forming oligopeptide segment are structurally simple substituents that perfectly fulfill these requirements. We synthesized a matrix of diacetylene model compounds that carried oligopeptide-polymer substituents with varying degrees of polymerization of the attached polymers and different length oligopeptide segments. We combined solution-phase IR spectroscopy, AFM imaging and the topochemical diacetylene polymerization as a highly sensitive probe for the molecular arrangement and the degree of order inside aggregates obtained in organic solvents. The thus determined molecular parameters for the reliable formation of well-defined nanoscopic fibrillar structures with uniform diameters, and defined helical 'core-shell' morphologies were then successfully transferred to analogous perylene bisimide and quaterthiophene derivatives, demonstrating the versatility and robustness of the chosen molecular design.

Synthesis of a poly­(m-phenylene) by Suzuki polycondensation (SPC) using an AB-type m-phenylene monomer is reported (A and B refer to bromo and boron functional groups, respectively). Despite the attempted high molecular weight products, SPC under the conventional conditions using Pd­[P­(p-Tol)3]3 as catalyst gave rise to oligomeric products only. They comprise cycles and several series of open-chain poly­(m-phenylene)­s with various end group patterns. These patterns were caused by side reactions such as ligand scrambling. Buchwald’s SPhos ligand was therefore alternatively employed for high turnover catalysis to accelerate SPC over such detrimental side reactions. This modification indeed led to the formation of high molecular weight products ∼40 kDa (DP ∼ 210), while oligomeric cyclic products still remained prominent. Cycle formation could, however, drastically be reduced by slow monomer addition. SPC was also performed in the presence of an excess monofunctional compound, R–A or R–B. The molecular weights of the products were found to be sensitive to the presence of R–B but not so much to R–A. This suggests a chain-growth-like mechanism as previously reported by Yokozawa et al. The modified SPC protocol was also used to demonstrate an efficient end-functionalization of the SPC products at both A and B termini with distinct chemical moieties. This revealed that the chain directionality expected from the AB monomer was largely retained when Pd­(dba)2 was used as palladium source for the SPC catalyst but not as for Pd­(OAc)2. This is presumably due to involvement of the homocoupling between phenyl boronates leading to reduction of Pd­(II).

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A chain of circumstantial evidence for the existence of the first fully conjugated, double-stranded cycles is presented. The products have the structure of the belt-region of fullerene C(84)(D(2)) and carry either four hexyl chains or four phenyl groups. The unsubstituted parent cycle is also presented. The chain of evidence is mainly based on mass spectrometric analysis and trapping reactions, the latter being supported by quantum mechanical calculations. It is also of importance that the phenyl-substituted and unsubstituted products cannot undergo a [1,5] hydrogen shift, the only reasonable side-reaction that recently could not be excluded for the alkyl-substituted analogue. It is concluded that the fully aromatic targets truly exist in the gas phase. Whether they can be generated in solution under the applied conditions cannot yet be firmly decided; theoretical evidence speaks against.

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