"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 incorporate, decorporate and exchange their components. On the other hand, such ability to undergo constitutional variation, in response to physical stimuli or chemical effectors, may be conferred upon molecules themselves by introduction of covalent bonds formed by reversible chemical reactions. Together, these features define a Constitutional Dynamic Chemistry (CDC) at both molecular and supramolecular levels. CDC takes advantage of constitutional dynamics to allow variation and selection, so as to achieve adaptation.The overall objective of the present proposal is to further explore the scope of CDC through:1) establishment of novel reversible covalent reactions, (in particular the synthetically important Diels-Alder and C=C bond forming reactions) without or with catalysis, and the physicochemical studies of the CDC processes;2) investigation of the modulation of dynamic libraries by either physical stimuli or chemical effectors and their adaptation to these sollicitations;3) development of constitutional dynamic materials, of either technological or biological interest, in particular dynamic polymers such as dynamic polyamides and dynamic biomolecules;4) elaboration of multiple dynamic systems, combining dynamic processes of different types, and their implementation in allosterically switchable synthetic reactions and in dynamic information processing devices.CDC represents a paradigm shift with respect to constitutionally static chemistry. In the process of reaching higher levels of complexity, it gives access to the generation of constitutional dynamic networks of interconverting constituents, that provide an approach to the chemistry of adaptive and evolutive systems."