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Control over the molecular organization of π-conjugated oligothiophenes into different types of supramolecular assemblies is key to their use in organic electronics but difficult to achieve as these chromophores have a pronounced tendency to aggregate. Herein we show that oligoprolines, which do not self-assemble on their own, control the self-assembly of quaterthiophenes. Spectroscopic, microscopic, and diffraction studies with quaterthiophene–oligoproline conjugates revealed the formation of mono- or double-layered sheets or, alternatively, helically twisted ribbons – depending on the length of the oligoproline. The dimensions of the nanoscopic objects, which extend into the micrometer regime, correlate with the molecular dimensions of the quaterthiophene–oligoproline building blocks., Chemical Science, 10 (20), ISSN:2041-6520, ISSN:2041-6539

A combinatorial screening revealed the peptide H-His-d-Leu-d-Asp-NH2 (1) as an additive for the generation of monodisperse, water-soluble palladium nanoparticles with average diameters of 3 nm and stabilities of over 9 months. The tripeptide proved to be also applicable for the size-controlled formation of other noble-metal nanoparticles (Pt and Au). Studies with close analogues of peptide 1 revealed a specific role of each of the three amino acids for the formation and stabilization of the nanoparticles. These data combined with microscopic and spectroscopic analyses provided insight into the structure of the self-assembled peptidic monolayer around the metal core. The results open interesting prospects for the development of functionalized metal nanoparticles.

Ordering π-systems into defined supramolecular structures is important for the development of organic functional materials. In recent years, peptides with defined secondary structures and/or self-assembly properties were introduced as powerful tools to order peptide-chromophore conjugates into different morphologies. This work explores whether or not the directionality of peptides can be used to control the self-assembly. The position of the π-system in conjugates between oligoprolines and perylene monoimide (PMI) chromophores was varied by attaching the PMI moiety to the second-to-last residue from the C- and N-termini, respectively. Microscopic and diffraction analysis revealed that the positional isomers form distinctly different supramolecular architectures that extend into the micrometer regime. NMR spectroscopic studies in solution phase allowed correlation of the self-assembly properties with markedly different conformational preferences of the isomeric building blocks. These insights enabled the design of building blocks with predictable self-assembly properties. Thus, the directionality of peptides offers exciting opportunities for controlling the self-assembly and electronic properties of π-systems.

Over the past two decades, peptides have expanded the toolbox of additives for the preparation of noble metal nanoparticles. Their functional and structural modularity and accompanying molecular recognition and self-assembly properties offer unique opportunities for the controlled formation of NPs. Within this review, we highlight recent examples for the use of peptides to control a) the size and shape of NPs and b) the spatial arrangement of NPs. The article focuses on examples where the peptides are directly involved in the bottom-up synthesis of the noble metal NPs.

Despite recent advances in the synthesis of increasingly complex topologies at the molecular level, nano- and microscopic weaves have remained difficult to achieve. Only a few diaxial molecular weaves exist-these were achieved by templation with metals. Here, we present an extended triaxial supramolecular weave that consists of self-assembled organic threads. Each thread is formed by the self-assembly of a building block comprising a rigid oligoproline segment with two perylene-monoimide chromophores spaced at 18 Å. Upon π stacking of the chromophores, threads form that feature alternating up- and down-facing voids at regular distances. These voids accommodate incoming building blocks and establish crossing points through CH-π interactions on further assembly of the threads into a triaxial woven superstructure. The resulting micrometre-scale supramolecular weave proved to be more robust than non-woven self-assemblies of the same building block. The uniform hexagonal pores of the interwoven network were able to host iridium nanoparticles, which may be of interest for practical applications.

l-proline and the tripeptide H-Pro-Pro-Asp-NH2 (1) have been supported, by adsorption, onto the surface of modified silica gels functionalized with a monolayer of covalently attached 1,2-dimethyl-imidazolium chloride, tetrafluoroborate or hexafluorophosphate ionic moieties, respectively. Three different linkers were used to attach the ionic liquid moiety to the surface of these supports. The resulting materials have been used as catalysts for the aldol reaction between acetone and several substituted benzaldehydes. Good yields and enantioselectivities, comparable to or better than those obtained under homogeneous conditions, were obtained. These materials are easily recovered by filtration, and studies regarding their re-use have been carried out. Studies performed using l-proline-supported materials have shown that the re-use of these materials is dependent on the nature of the linker. The supported tripeptide H-Pro-Pro-Asp-NH2 gave higher enantioselectivities than those obtained with supported-proline. Recycling investigations using tripeptide-supported materials showed continued good selectivities but diminishing conversions over consecutive runs. l-proline-supported materials however, can be used at least nine times without loss of either conversion or selectivity. This journal is