Wiktionary
phthalocyanine
n. (context organic compound English) Any of a family of macrocyclic compounds having a structure similar to that of porphyrin; they are blue/green pigments that are used in plastics and enamels
Wikipedia
Phthalocyanine
Phthalocyanine is an intensely blue-green-coloured aromatic macrocyclic compound that is widely used in dyeing. Phthalocyanines form coordination complexes with most elements of the periodic table. These complexes are also intensely colored and also are used as dyes or pigments.