Metal induced folding: synthesis and conformational analysis of the lanthanide complexes of two 44-membered hydrazone macrocycles

Hydrazone exchange: a viable route for the solid-tethered synthesis of [2]rotaxanes

Using a hydrazone exchange methodology, resin beads were functionalised with [2]rotaxanes at up to 80% efficiency—higher than using other dynamic or irreversible synthetic approaches to form self-assembled structures on solid supports.

A dynamic combinatorial library for biomimetic recognition of dipeptides in water

Small peptides are involved in countless biological processes. Hence selective binding motifs for peptides can be powerful tools for labeling or inhibition. Finding those binding motifs, especially in water which competes for intermolecular H-bonds, poses an enormous challenge. A dynamic combinatorial library can be a powerful method to overcome this issue. We previously reported artificial receptors emerging form a dynamic combinatorial library of peptide building blocks. In this study we aimed to broaden this scope towards recognition of small peptides. Employing CXC peptide building blocks, we found that cyclic dimers of oxidized CFC bind to the aromatic peptides FF and YY (K ≈ 229–702 M⁻¹), while AA binds significantly weaker (K ≈ 65–71 M⁻¹).

An allosteric receptor by simultaneous "casting" and "molding" in a dynamic combinatorial library

Allosteric synthetic receptors are difficult to access by design. Herein we report a dynamic combinatorial strategy towards such systems based on the simultaneous use of two different templates. Through a process of simultaneous casting (the assembly of a library member around a template) and molding (the assembly of a library member inside the binding pocket of a template), a Russian-doll-like termolecular complex was obtained with remarkable selectivity. Analysis of the stepwise formation of the complex indicates that binding of the two partners by the central macrocycle exhibits significant positive cooperativity. Such allosteric systems represent hubs that may have considerable potential in systems chemistry.

Transient substrate-induced catalyst formation in a dynamic molecular network

In biology enzyme concentrations are continuously regulated, yet for synthetic catalytic systems such regulatory mechanisms are underdeveloped. We now report how a substrate of a chemical reaction induces the formation of its own catalyst from a dynamic molecular network. After complete conversion of the substrate, the network disassembles the catalyst. These results open up new opportunities for controlling catalysis in synthetic chemical systems.

Hydrazone-based switches, metallo-assemblies and sensors

The hydrazone functional group has been extensively studied and used in the context of supramolecular chemistry. Its pervasiveness and versatility can be attributed to its ease of synthesis, modularity, and most importantly unique structural properties, which enable its integration in different applications. This review provides an overview of the utilization of hydrazones in three supramolecular chemistry related areas: molecular switches, metallo-assemblies and sensors. These topics were chosen because they highlight the diversity of hydrazones, and emphasize their uniqueness vis-à-vis the imine functional group. Discussion entails (i) chemical and light activated switching of hydrazones, and how this can be used in controlling the properties of self-assembled systems, (ii) the use of hydrazones in the formation of dynamic and stimuli responsive metallogrids, and (iii) the use of hydrazones in detecting metal cations (Zn(2+), Cu(2+), Hg(2+), etc.), anions (F(-), CN(-), P2O7(4-), etc.) and neutral molecules (amines, water, Cys, etc.).