The synthetic quest for 'splendid isolation' within phthalocyanine materials

Phthalocyanine (Pc) derivatives in which substituents hold the Pc units in isolation from one another in the solid slate are potentially useful materi als. Three synthetic approaches to achieve this goal are described: the con struction of a dendrimer about a Pc core; the incorporation of alkyl side c hains which are forced to lie out of the plane of the macrocycle; and the s ythesis of sterically crowded hexadeca-substituted derivatives. The effecti veness of each of these strategies is readily measured by comparing the vis ible 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 t he substituents is of secondary importance for their efficiency in inducing Pc isolation. Of more importance is the substituents' adopted position rel ative to the Pc ring. Copyright (C) 2000 John Wiley &. Sons, Ltd.