Most chemical reactions proceed predominantly in one direction: reactants are converted into products and the system eventually reaches a stable end state. In this sense, many reactions resemble chemical “one-way streets”. In contrast, Project SUPRANET focused on a fascinating and much less explored class of reactions that proceed in both the forward and the backward direction. Such reversible reactions form chemical “two-way streets”, enabling molecules to continuously interconvert and explore many different structures. These reversible processes are the foundation of dynamic chemical networks, in which many compounds coexist and transform into one another until the most stable or best-adapted structures emerge. Chemical “two-way streets” can operate in two conceptually different ways. First, molecules can move forward and backward along the same reaction pathway, analogous to walking along the same trail in both directions. Second, they can undergo cyclic or “round-trip” processes, where forward and backward transformations follow different routes through the reaction network. Project SUPRANET explored both types of dynamic behaviour and used them as design principles to construct adaptive supramolecular systems.
The scientific challenge addressed by the project was to harness such dynamic reaction networks to discover and control complex functional molecules. Conventional molecular design typically relies on stepwise synthesis of predetermined targets. In contrast, dynamic chemical networks allow molecules to be selected and amplified from mixtures through processes such as self-assembly, template effects, or kinetic trapping. Understanding and exploiting these processes is a central question in modern chemistry because they provide a pathway toward adaptive molecular systems resembling the behaviour of biological chemistry.
The importance of this research extends beyond fundamental science. Dynamic molecular systems underpin key biological functions such as molecular recognition, membrane transport, and the emergence of self-replication. By learning how to construct and control similar behaviour in synthetic systems, chemists can develop new strategies for sensing, drug delivery, ion transport, responsive materials, and other technologies relevant to medicine and biotechnology.
Within this context, SUPRANET pursued four overarching objectives.
First, the project aimed to identify and construct new anion and ion-pair receptors, particularly for chloride ions, using dynamic covalent self-assembly. Such receptors may ultimately contribute to strategies addressing diseases linked to dysfunctional ion transport, such as cystic fibrosis.
Second, the project sought to develop supramolecular host structures capable of kinetically trapping ions—conceptually described as molecular “prisons”—that could enable controlled transport of ions across membranes and their release under defined conditions.
Third, the project investigated network-based chemical replication processes, exploring how dynamic reaction cycles might generate self-amplifying behaviour and thereby shed light on fundamental questions about the chemical origins of life.
Fourth, the project explored fuel-driven and network-controlled self-assembly, including transient vesicle-like systems that could function as delivery platforms for molecular cargo.
