Tetratopic bis(4,2′:6′,4′′-terpyridine) and bis(3,2′:6′,3′′-terpyridine) Ligands as 4-Connecting Nodes in 2D-Coordination Networks and 3D-Frameworks

Ditopic, 4,2':6',4''-terpyridine (4,2':6',4''-tpy) and 3,2':6',3''-terpyridine (3,2':6',3''-tpy) present a divergent N,N' -donor set (the central N atom typically being non-coordinated) and are ideal building blocks for the assembly of coordination polymers and networks. The step from ditopic to tetratopic ligands which contain two interconnected 4,2':6',4''-tpy or 3,2':6',3''-tpy metal-binding domains renders the ligand capable of acting as a 4-connecting node and is a successful route to increasing the dimensionality of the assembly. In this short overview, we illustrate the recent development of the use of bis(4,2':6',4''-tpy) and bis(3,2':6',3''-tpy) ligands and compare strategies using either ditopic or tetratopic ligands.