Monomeric, not tetrameric species are responsible for the colossal dielectric constant of copper phthalocyanine derived from pyromellitic dianhydride†
Abstract
Mass spectrometric analysis indicates that the copper(II) phthalocyanine derived from pyromellitic dianhydride is a mononuclear species, not a tetranuclear species as previously thought. The peripheral substitution of the phthalocyanine core with eight carboxylic acid groups, rather than extended conjugation, is responsible for the extraordinary dielectric constant associated with this material.