Georges Tsoucaris - Böcker

The Supramolecular Compounds refer to organised multi-molecular assemblies and associated phenomena. The stability and the properties of these compounds strongly involve structural three-dimensional (3D) information. The crystal itself can be considered as a giant supermolecule. Thus, a thorough understanding of crystal structures and crystal growth provides a unique information on the intermolecular interactions. Indeed, each crystal reflects in a particular way the recognition properties of molecules. More so, modern crystallography allows to study in detail two- or three-component crystalline solids in which the recognition processes can be seen from the structural standpoint. Crystallography of smaller and smaller single crystals, faster and faster experiments, time-resolved x-ray crystallography, are extremely potent source of physico-chemical information. The present Advanced Study Institute (A.S.I.) - which was planned five years ago as the 22nd Course of the International School of Crystallography (director: T. L. BLUNDELL), 1-11 June 1995, E.Majorana Centre, Erice, Italy - is probably the first international meeting specifically devoted to the Crystallography of Supramolecular Compounds. The presence of crystallographers, chemists and physicists enhanced the coherence of the typical sequence: Conception and Design - Synthesis - Structure and Visualisation - Properties. The interactive and interdisciplinary character of this research is central to the development of general structural models for a large spectrum of compounds: ionophores, cryptates, fullerenes, calixarenes, cyclodextrins, cyclotriveratrylenes, pillar type compounds, zeolites, hydrates, solvates and others.

There have been several recent breakthroughs in the supramolecular domain: larger molecular components are being synthesized; 2D layers involving multiple recognition sites; crystals with intricate building blocks are being designed; more components are being used in assembly and self-assembly "algorithms" (some having molecular weights as high as 15,000); and there is an increasing versatility in applications. The difficulty in characterizing and obtaining structural information on such large assemblies has increased to such a level that no single technique is now adequate. Various methods have now been upgraded and are being combined: X-ray diffraction (structures with hundreds of independent atoms), NMR, AFM/STM (manipulation of a single molecule), FAB/MS, time-resolved techniques up to the picosecond range, new computational approaches, and others. The present book aims to shed light on the most recent developments in both the synthesis of novel assemblies and on current methods for their characterization.

This work delineates the contours of molecular and structural archaeology as an emergent interdisciplinary field based on structural analysis at the molecular level and examines novel methodologies to reconstruct the synthesis and long-term transformation of materials used in antiquity. The focus of this volume is on cosmetic and therapeutic materials. As such, it casts an entirely new light on the knowledge possessed by the ancients, based on the complete identification of complex materials and preparations found in closed vessels in ancient tombs. It appears that as early as 2000 BCE the necessary technology was available to conduct wet chemical synthesis of new compounds not known as natural products. The materials as we analyse them today have their own prior history, and disentangling the effects of extreme long-term storage forms part of the puzzle, which may possibly be resolved by means of simulation experiments.

This work delineates the contours of molecular and structural archaeology as an emergent interdisciplinary field based on structural analysis at the molecular level and examines novel methodologies to reconstruct the synthesis and long-term transformation of materials used in antiquity. The focus of this volume is on cosmetic and therapeutic materials. As such, it casts an entirely new light on the knowledge possessed by the ancients, based on the complete identification of complex materials and preparations found in closed vessels in ancient tombs. It appears that as early as 2000 BCE the necessary technology was available to conduct wet chemical synthesis of new compounds not known as natural products. The materials as we analyse them today have their own prior history, and disentangling the effects of extreme long-term storage forms part of the puzzle, which may possibly be resolved by means of simulation experiments.

The objectives of the ARW were: - identifying areas and highlighting approaches by which large Supramolecular (SM) Assemblies can be synthesised - reviewing and combining methods to characterise and analyse such assemblies. The first part of the ARW is devoted to reviewing synthetic achievements in recent years for several families of SM compounds, and to bringing out principles for crystal structure design, including novel quantum mechanical methods. Synthesis pertains both to the chemical synthesis of components for SM assembly, and to the subsequent assembly process based on complementarity and non-covalent interactions. The elaboration of multiple recognition "algorithms" concurrently employed (for instance, 1t-1t and hydrogen bonds) has recently reached a high degree of sophistication in the sequence: Molecules -7 Supermolecule -7 SM array -7 Crystal or Conglomerate Novel Large Assemblies comprise synthetic entities with molecular weight as high as 15000, and hybrid SM assemblies between synthetic molecules and DNA. Further developments are foreseen at a higher level of organisation, such as between supermolecules or with electromagnetic fields in photochemical processes. Creation of 2D Assemblies is now a powerful tool for creation and study of SM interactions. Moreover, much is to be learned in going from 2D to 3D assemblies in crystal growth and other forms of organisation such as micelles or liquid crystals. On the other hand, crystal engineering based on Molecular Recognition in the Crystal State leads to novel 2D assemblies occurring within predesigned crystal structures (hydrophobic organic clays or nanoporous networks).