Closing and coupling: metal linked biliazine dimers

Abstract

Biliazines, tetradentate chelates similar to the bilin class of heme metabolites, are ring open phthalocyanine analogs where the chelate ring is closed by a hydrogen bond. Linked dimers of biliazines, incorporating both pyrazole and indazole units, can be produced via a self-assembly reaction between the diiminoisoindoline-pyrazole and indazole chelate precursors and zinc ion in a 4 : 3 ratio. The dimers are comprised of zinc metalated biliazines linked by a third tetrahedral zinc metal ion. The closure of the ring with zinc ion does not induce the formation of an aromatic ring current in either the pyrazole or indazole-based dimers.