Current Challenges on Large Supramolecular Assemblies

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).