Direction of copper phthalocyanine crystallization using in situ generated tethered phthalocyanines

Copper phthalocyanine in the metastable α crystal polymorph can be obtained directly from phthalonitrile or from phthalodiimide, which would normally give the more stable β crystal form, by the inclusion of 3% or greater of the sulfide 2 or the diimide 3. The resulting α form material does not revert to the β form upon treatment in boiling xylene, unlike conventionally prepared α copper phthalocyanine.