Chirality in Supramolecular Coordination Compounds

Supramolecular chirality is widely manifested in nature for example, the DNA double helix,the protein single helices and, in humans, rhinovirus 14, a member of the major rhinoviras receptor class, possesses a protein capsid that is composed of 60 protomers arranged in an icosahedrally symmetric arrayJ As shown previously in this book, at the molecular level, chirality is very important in asymmetric catalysis for the creation of novel chiral molecules however, more recently an increasing amount of attention has been drawn to chiral supramolecular assemblies. On the supramolecular level, chirality involves the nonsymmetric arrangement of molecular subunits in a noncovalent assembly via weak interactions such as hydrogen bonding, metal coordination and n-n interaction. 

In the first part of this chapter, we will present chiral supramolecular architectures formed from achiral building units that are linked via metal-ligand coordination, where chirality of the assembly results only from the asymmetric arrangement of the molecular components. In the second section, we will deal with chiral assemblies that result from resolved chiral bridging ligands, where chiral information can be transferred to the metal centre and hence a predetermination of the absolute configuration at the metal centre can be achieved and, eventually, the control of the chirality of the supramolecular architecture which can also be defined as stereoselective asymmetric supramolecular assembly . 

Although the number of examples of chiral assemblies formed by the first method have been increasing steeply, and include helicates, trigonal antiprisms, tetrahedral, trigonal bipyramid and cuboctahedra, interest in stereoselective syntheses in coordination chemistry has only been developed in recent years and only a few examples have been reported. 

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