Nobel Centennial Symposia
"Frontiers of Molecular Science"

December 4-7, 2001
Friiberghs Manor, Örsundsbro and Stockholm University

Steps Towards Complex Matter: Information, Self-organization and Adaptation in Molecular and Supramolecular Systems

by Jean-Marie Lehn
ISIS, Université Louis Pasteur, Strasbourg and Collège de France, Paris

One of the major lines of development of chemical science in the coming century resides in the ever clearer perception, deeper analysis and more deliberate application of information features in the elaboration and transformation of matter, thus tracing the path from merely condensed matter to more and more highly organized matter towards systems of increasing complexity.

A most basic and far-reaching contribution of supramolecular chemistry is the implementation in chemical science of the concept of molecular information and its corollaries, instructions and programmed chemical systems, with the aim of gaining progressive control over the organization of matter, over its spatial (structural) and temporal (dynamical) features.

Supramolecular chemistry is actively exploring systems undergoing self-organization, i.e. systems capable of spontaneously generating well-defined functional supramolecular architectures by self-assembly from their components. Self-organization processes may be directed via the molecular information stored in the covalent framework of the components and read out at the supramolecular level through specific interactional algorithms, thus behaving as programmed chemical systems.

The control provided by self-organization processes allows the development of functional supramolecular devices, defined as structurally organized and functionally integrated systems built from suitably designed molecular components performing a given function (e.g. photoactive, electroactive, ionoactive, etc.) and containing the features required for assembly into an organized supramolecular architecture. Self-organization processes also give access to advanced functional supramolecular materials, such as supramolecular polymers and liquid crystals.

The design of molecular information controlled, "programmed" self-organising systems provides an original approach to nanoscience and nanotechnology. In particular, the spontaneous but controlled generation of well-defined, functional supramolecular architectures of nanometric size through self-organization represents a means of performing programmed engineering and processing of nanomaterials.

Technologies resorting to self-organization processes are in principle able to provide a powerful alternative nanofabrication and nanomanipulation procedures by making use of the spontaneous but controlled generation of the desired superstructures and devices from suitably instructed and functional building blocks.

Supramolecular chemistry is also intrinsically a dynamic chemistry in view of the lability of the interactions connecting the molecular components of a supramolecular entity. Furthermore, because of the ability of supramolecular species to exchange their constituents, they have also combinatorial capacity.

Consequently, supramolecular devices and materials are by nature dynamic species, whose constituents are linked through reversible connections and undergo spontaneous and continuous assembly/deassembly processes in a given set of conditions. Because of their intrinsic ability to exchange their constituents, they have also combinatorial character so that they may be considered as dynamic combinatorial devices and materials. Being instructed, dynamic and combinatorial, they may in principle select their constituents in response to external stimuli or environmental factors and therefore behave as adaptive systems.

The same considerations apply to molecular entities constructed from components linked through reversible covalent connections. Together, such molecular and supramolecular systems embody a dynamic combinatorial chemistry.

The merging of the features of supramolecular systems: - information and programmability, - dynamics and reversibility, - combinatorics and structural diversity, points towards the emergence of adaptive chemistry, where design meets selection. A further development will concern the inclusion of the arrow of time, i.e. of non-equilibrium, irreversible processes and the exploration of the frontiers of chemical evolution towards the establishment of evolutive chemistry, where the features acquired by adaptation are conserved and transmitted. In combination with the corresponding fields of physics and biology, chemistry thus plays a major role in the progressive elaboration of a science of informed, organized, evolutive matter, a science of complex matter.

General references

J.-M. LEHN, Supramolecular Chemistry: Concepts and Perspectives, VCH, Weinheim, 1995.
J.-M. LEHN in Supramolecular Chemistry: Where It is and Where It is Going (R. Ungaro, E. Dalcanale, eds.), Kluwer Dordrecht, 1999, pp.287-304.
J.-M. LEHN, Chem. Eur. J., 1999, 5, 2455.
J.-M. LEHN, Chem. Eur. J., 2000, 6, 2097.