Coordination chemistry of expanded porphyrins

Expanded porphyrins are a class of porphyirinoid macrocycles possessing more than four pyrrole/other heterocyclic rings and multiple meso-carbon bridges in their conjugated structural frame-work. Expanded porphyrins are different from tetrapyrrolic porphyrin macrocycles in having larger pi-Celectron circuit, larger sized macrocyclic core and are capable of exhibiting Huckel and Mobius topologies. The coordination chemistry of expanded porphyrins is distinct compared to porphyrins as they are capable of binding larger sized metal ions and also more than one metal ion in their macrocyclic core. In this review article, we summarize the syntheses, structure and properties of coordination complexes of expanded porphyrins spanning pentaphyrins (including sapphyrins and smaragdyrins), hexaphyrins (including rubyrins, amethyrins, and isoamethyrins), heptaphyrins, octaphyrins, nonaphyrins, decaphyrins and larger macrocycles containing different types of linkages between interconnected pyrrole units. (C) 2019 Elsevier B.V. All rights reserved.