Ligand directed self-assembly of polymetallic [n × n] grids: rational routes to large functional molecular subunits?

Poly-(n)-topic ligands with a linear arrangement of coordination pockets self-assemble, generally in high yield, to produce square [n × n] grid complexes. Oligomeric, non-grid intermediates, identified by structural studies, have shown alternative construction pathways, but have also indicated possible mechanistic routes to grid assembly. Various factors are considered critical to grid formation, including reaction pH, metal ion identity, CFSE, and metal ion redox behaviour. Ultimately the design of the ligand is pivotal to successful grid self-assembly, and the size of the [n × n] grid is largely limited only by the synthetic limitations of the ligands themselves.