Anion binding: A new direction in porphyrin-related research

Abstract
A new approach to the chelation of anionic substrates, based on the use of large, pyrrole-containing macrocycles, the so-called "expanded porphyrins", is described. This anion binding, which is without precedent in simpler porphyrin-type systems, is manifest both in the solid state and in solution. In the present paper, it is illus- trated in terms of solid state structural results obtained from single-crystal X-ray diffraction structural analyses of various anion complexes of three prototypic sys- tems, namely the sapphyrins, anthraphyrins, and rubyrins.