Organic nanowires and microfibers are excellent model systems for charge transport in organic semiconductors under nanoscopic confinement and may be relevant for future nanoelectronic devices. For this purpose, however, the preparation of well-ordered organic nanowires with uniform lateral dimensions remains a challenge to achieve. Here, we used the self-assembly of oligopeptide-substituted perylene bisimides and quaterthiophenes to obtain well-ordered nanofibrils. The individual nanofibrils were investigated by spectroscopic and imaging methods, and the preparation of hierarchically structured microfibers of aligned nanofibrils allowed for a comprehensive structural characterization on all length scales with molecular level precision. Thus, we showed that the molecular chirality resulted in supramolecular helicity, which supposedly serves to suppress lateral aggregation. We also proved that, as a result, the individual nanofibrils comprised a single stack of the π-conjugated molecules at their core. Moreover, the conformational flexibility between the hydrogen-bonded oligopeptides and the π-π stacked chromophores gave rise to synergistically enhanced strong π-π interactions and hydrogen-bonding. The result is a remarkably tight π-π stacking inside the nanofibrils, irrespective of the electronic nature of the employed chromophores, which may render them suitable nanowire models to investigate one-dimensional charge transport along defined π-π stacks of p-type or n-type semiconductors.

Nanostructured carbonaceous materials, that is, carbon materials with a feature size on the nanometer scale and, in some cases, functionalized surfaces, already play an important role in a wide range of emerging fields, such as the search for novel energy sources, efficient energy storage, sustainable chemical technology, as well as organic electronic materials. Furthermore, such materials might offer solutions to the challenges associated with the on-going depletion of nonrenewable energy resources or climate change, and they may promote further breakthroughs in the field of microelectronics. However, novel methods for their preparation will be required that afford functional carbon materials with controlled surface chemistry, mesoscopic morphology, and microstructure. A highly promising approach for the synthesis of such materials is based on the use of well-defined molecular precursors.

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.

We developed MUSIC-mode atomic force microscopy (AFM) to emulate intermittent contact mode AFM without a feedback loop and in the absence of lateral forces. This single-pass approach is based on maps of amplitude-phase-distance curves and allows the height and phase images to be simultaneously obtained for almost any amplitude set point. This is advantageous for determining the shape and nanomechanical properties of very soft and fragile samples. As an example, we studied supramolecular aggregates of oligothiophenes, which form ≈15 nm wide fibrils with a rigid core and a soft shell.

Carbon-rich organic compounds containing a series of conjugated triple bonds (oligoynes) are relevant synthetic targets, but an improved access to oligoynes bearing functional groups would be desirable.