Bridging ligands , supramolecular assembly

A review13 with 53 references of the transition-metal mediated supramolecular self-assembly is presented. Focus is on the self-assembly of macrocycles, catenanes, and cages from (en)Pd(N03)2 and pyridine-based bridging ligands. 

A helical homobimetallic mercury(II) complex with a bridging bis(NHC) ligand serves as a starting point for a supramolecular assembly. Also tetrameric cyclic palladium(II) complexes have been obtained with bridging NHC-pyridine ligands. 

In this section, we describe the construction of metal-containing polymers and supramolecular assemblies, in which metallic centers are linked by a bridging diisocyanide ligand along with their photophysical properties (Fig. 3). 

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 . 

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