Ditopic and Tetratopic 4,2':6',4''-Terpyridines as Structural Motifs in 2D- and 3D-Coordination Assemblies

We overview the coordination chemistry of ditopic and tetratopic ligands with 4,2':6',4''-terpyridine metal-binding domains and illustrate the adaptability of these divergent ligands as building blocks in 2Dand 3D-coordination networks. The ditopic ligands we discuss are limited to roles as linkers in coordination assemblies, while the tetratopic ligands have the potential to be 4-connecting nodes. Both diand tetratopic ligands are equipped with functionalities, typically alkyloxy chains, the nature of which has a profound effect upon the coordination assembly. Combinations of 4-connecting ligand nodes with metal-linkers lead to both 2Dand 3D-networks, while combinations of 4-connecting metal and ligand nodes give 3D-architectures. We also demonstrate constraint of the coordination assembly to 2-dimensions by depositing ditopic 4,2':6',4''-terpyridine ligands onto Au(111) or Cu(111) platforms with Cu adatoms in the former case; highly ordered ladder assemblies result which are independent of solvent molecules or anions.