REVIEW COMMENTARY p-p INTERACTIONS IN SELF-ASSEMBLY

The recent surge of interest in the control of molecular organization in both the solution state (i.e. self-assembly) and the solid state (i.e. crystal engineering) has led researchers to recognize increasingly the importance of weak noncovalent interactions. The design and synthesis of an efficient molecular construction set are dependent upon a very close interplay between x-ray crystallography and synthetic chemistry. p‐p Stacking interactions between p-donors, such as hydroquinone, resorcinol or dioxynaphthalene residues, and p-accepting ring systems, such as bipyridinium or pextended viologen units, can govern the self-assembly of a variety of complexes and interlocked molecular compounds in both the solid and solution states. Non-covalent bonding interactions (i.e. p‐p interactions) can be considered as information vectors: they define and rule the self-assembly processes that lead to the formation of the desired molecular and supramolecular architectures, and thereafter they still govern the dynamic processes occurring within the selfassembled structures and superstructures. The manner in which such molecules and supermolecules can contribute to an understanding of non-covalent interactions at both structural and superstructural levels is described, with reference to numerous examples of self-assembly processes in synthesis, of dynamic processes in the solution state, and of the packing of molecules and molecular complexes in the solid state. © 1997 by John Wiley & Sons, Ltd.