This critical review surveys factors involved in the convergent self-assembly of square [n×n] (n = 2–5) polymetallic grids, using ligands with encoded coordination information appropriate to the metal ion’s coordination algorithm. While entropic factors drive these reactions, other effects, including metal ion CFSE, ligand conformational character, electrostatic factors etc., can lead preferentially to non-grid oligomers. It will be of interest to the general supramolecular community, particularly coordination chemists attempting to create predetermined architectures, with applications oriented molecular based properties (86 references).

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.

The first X-ray structural determinations of pristine fullerene C₆₀, cocrystallized 1 : 1 with corannulene and with its pentaalkyl-substituted derivative, 1,3,5,7,9-penta-tert-butyl-corannulene, have now been achieved.