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Frontiers in Supramolecular Chemistry
Towards Adaptive Chemistry

Final Report Summary - SUPRADAPT (Frontiers in Supramolecular ChemistryTowards Adaptive Chemistry)

Molecular chemistry has developed a wide range of very powerful procedures for mastering the organisation of matter and building ever more complicated molecules from atoms linked by strong connections, covalent bonds. Supramolecular chemistry lies beyond molecular chemistry. It aims at constructing and implementing highly complex chemical systems from molecular components held together by non-covalent intermolecular forces.
Supramolecular chemistry is intrinsically a dynamic chemistry in view of the lability of the interactions connecting the molecular components of a supramolecular entity and the resulting ability of supramolecular species to exchange their constituents. The same holds for molecular chemistry when the molecular entity contains covalent bonds that may form and break reversibility, so as to allow a continuous change in constitution by reorganization and exchange of building blocks. These features define a Constitutional Dynamic Chemistry (CDC) on both the molecular and supramolecular levels. CDC introduces a paradigm shift with respect to the traditional constitutionally static chemistry. The latter relies on design for the generation of a target molecular entity, whereas CDC takes advantage of dynamic molecular diversity to perform component selection and to allow for constitutional variation and thus for the adaptation of a chemical system to specific conditions.
The present project explores and exploits CDC, in particular with respect to its ability to operate on dynamic constitutional diversity in response to either internal or external factors. We have investigated how constitutional dynamics allow for adaptation, through component exchange and selection with generation of the fittest constituent(s) in response to different agents:
- physical stimuli such as light, leading to photo-induced constitutional change with photoselection of components,
- chemical effectors such as metal ions, leading to constitutional change induced by metal ion complexation with metalloselection of components,
- environmental effects, such as phase change and distribution between organic and aqueous phases, towards the redistribution of components leading to constituents best adapted to each phase.
The implementation of CDC processes in extended dynamic networks, their introduction into out-of-equilibrium conditions and the operation of learning features represent three important steps towards the design of complex chemical systems.
The introduction of constitutional dynamics into materials science opens perspectives towards adaptive materials and technologies, presenting attractive behavioural features (such as self-healing), in particular dynamic polymers may undergo modification of their properties (mechanical, optical, etc.) through component exchange and recombination in response to physical or chemical agents. We thus have obtained polymeric materials based on covalent dynamic polymers that present self-healing properties. Such adaptive materials offer novel properties opening numerous opportunities for soft matter technologies.
Multiple developments towards a chemistry presenting adaptive features await to be implemented from the practical point of view too. In particular, there is little doubt that constitutional dynamic materials, dynamic polymers and CDC in general are likely to find their applications in the development of adaptive technologies, involving both the materials and the processes to access them.