Grid complex

Latticial metal complex or grid complex is a supramolecular complex of several metal atoms and coordinating ligands which form a grid-like structural motif. The structure formation usually occurs while on thermodynamic molecular self-assembly. They have properties that make them interesting for information technology as the future storage materials.^[1] Chelate ligands are used as ligands in tetrahedral or octahedral structures, which mostly use nitrogen atoms in pyridine like ring systems other than donor centers. Suitable metal ions are in accordance with octahedral coordinating transition metal ions such as Mn or rare tetrahedral Coordinating such as Ag used. ^[1]

Nomenclature

The nomenclature is based on [n × m] G, n corresponds to the number of ligands above the metal ion level, m the number below ones. In case of using only one ligand type, the homoleptic grid is formed in a square [nxn] structure. When using different ligands arise heteroleptic complexes, however, compete with the homoleptic. The number of metal ions is always n + m.

Application

The grid complexes exhibit pH-dependent changes in the optical absorption, electronic spin states and reversible redox states. The latticial metal complexes may thus be used theoretically for information storage and processing in the future.^[2][3][4]

Other Uses

An interwoven grid complex has been used to template the synthesis of a doubly-twisted [2]catenane (otherwise known as a Solomon Link).^[5] The unique arrangement of interwoven ligands around the planar array of iron, zinc, or cobalt ions generated the crossing points required to covalently trap the interlocked structure using ring-closing metathesis. Building on this discovery, 2 × 2 interwoven grids were used to template the synthesis of more topologically complex molecules: a six-crossing doubly-interlocked [2]catenane and a granny knot.^[6] In 2021, the first report of a 3 × 3 interwoven grid was published. It was used to template the synthesis of a molecular Endless Knot.^[7]

References

1. J.-M. Lehn et al., Angew. Chem., 2004, 116, S. 3728–3747.
2. Ruben, Lehn, Chem. Commun., 2003, S. 1338–1339.
3. Ruben et al., Chem. Eur. J., 2003, 9, S. 291–299.
4. Müller, Lehn et al., Angew. Chem., 2005, 117, S. 8109–8113.
5. Beves, Jonathon E.; Danon, Jonathan J.; Leigh, David A.; Lemonnier, Jean-François; Vitorica-Yrezabal, Iñigo J. (22 June 2015). "A Solomon Link through an Interwoven Molecular Grid". Angewandte Chemie International Edition. 54 (26): 7555–7559. doi:10.1002/anie.201502095. PMC 4479027. PMID 25960366.
6. Danon, Jonathan J.; Leigh, David A.; Pisano, Simone; Valero, Alberto; Vitorica-Yrezabal, Iñigo J. (15 October 2018). "A Six-Crossing Doubly Interlocked [2]Catenane with Twisted Rings, and a Molecular Granny Knot". Angewandte Chemie International Edition. 57 (42): 13833–13837. doi:10.1002/anie.201807135. PMC 6221036. PMID 30152565.
7. Leigh, David A.; Danon, Jonathan J.; Fielden, Stephen D. P.; Lemonnier, Jean-François; Whitehead, George F. S.; Woltering, Steffen L. (15 February 2021). "A molecular endless (74) knot". Nature Chemistry. 13 (2): 117–122. doi:10.1038/s41557-020-00594-x. S2CID 229163544.