The synthetic quest for ‘splendid isolation’ within phthalocyanine materials

Abstract

Phthalocyanine (Pc) derivatives in which substituents hold the Pc units in isolation from one another in the solid state are potentially useful materials. Three synthetic approaches to achieve this goal are described: the construction of a dendrimer about a Pc core; the incorporation of alkyl side chains which are forced to lie out of the plane of the macrocycle; and the synthesis of sterically crowded hexadeca-substituted derivatives. The effectiveness of each of these strategies is readily measured by comparing the visible absorption spectrum of a spin-coated film with that obtained from the non-aggregated Pc in dilute solution. These studies show that the size of the substituents is of secondary importance for their efficiency in inducing Pc isolation. Of more importance is the substituents' adopted position relative to the Pc ring.