Localized Supramolecular Peptide Self‐Assembly Directed by Enzyme‐Induced Proton Gradients

Electrodes are ideal substrates for surface localized self‐assembly processes. Spatiotemporal control over such processes is generally directed through the release of ions generated by redox reactions occurring specifically at the electrode. The so‐used gradients of ions proved their effectiveness over the last decade but are in essence limited to material‐based electrodes, considerably reducing the scope of applications. Herein is described a strategy to enzymatically generate proton gradients from non‐conductive surfaces. In the presence of oxygen, immobilization of glucose oxidase (GOx) on a multilayer film provides a flow of protons through enzymatic oxidation of glucose by GOx. The confined acidic environment located at the solid–liquid interface allows the self‐assembly of Fmoc‐AA‐OH (Fmoc=fluorenylmethyloxycarbonyl and A=alanine) dipeptides into β‐sheet nanofibers exclusively from and near the surface. In the absence of oxygen, a multilayer nanoreactor containing GOx and horseradish peroxidase (HRP) similarly induces Fmoc‐AA‐OH self‐assembly.     

Building Supramolecular DNA‐Inspired Nanowires on Gold Surfaces: From 2D to 3D

Three building blocks have been designed to chemically link to a gold surface and vertically self‐assemble through thymine–adenine hydrogen bonds. Starting from these building blocks, two different films were engineered on gold surface. Film 1 consists of adenine linked to lipoic acid (Lipo–A) to covalently bind to the gold surface, and ZnTPP linked to a thymine (T–ZnTPP). Film 2 has an additional noncovalently linked layer: a helical undecapeptide analogue of the trichogin GA IV peptide, in which four glycines were replaced by four lysines to favor a helical conformation and reduce flexibility and the two extremities were functionalized with thymine and adenine to enable Lipo–A and T–ZnTPP binding, respectively. These films were characterized by electrochemical and spectroscopic techniques, and were very stable over time and when in contact with solution. Under illumination, they could generate current with higher efficiency than similar previously described systems.     

Supramolecular Nanotubules as a Catalytic Regulator for Palladium Cations: Applications in Selective Catalysis

Despite the recent development of highly efficient and stable metal catalysts, conferral of regulatory characteristics to the catalytic reaction in heterogeneous systems remains a challenge. Novel supramolecular nanotubules were prepared by alternative stacking from trimeric macrocycles, which was found to be able to coordinate with Pd cations. The Pd complexes exhibited a high catalytic performance for C−C coupling reaction. Notably, the tubular catalyst was observed to be controlled by supramolecular reversible assembly and showed superior heterogeneous catalytic activity, which was maintained for a number of cycles or reuse under an aerobic environment. Furthermore, the supramolecular catalyst showed unprecedented selectivity for the multifunctional coupling reaction and was able to serve as a new constructor of asymmetrical compounds.     

Cation‐Driven Self‐Assembly of a Gold(I)‐Based Metallo‐Tweezer

A combination of self‐complementary π–π‐stacking interactions and metallophilic interactions triggered the self‐assembly of a new digold(I) metallo‐tweezer in the presence of several types of M⁺ ions. Titrations by fluorescence spectroscopy enabled the determination of the association constants of the resulting inclusion duplex complexes.