Derivatizable phthalocyanine with single carboxyl group: Synthesis and purification

Phthalocyanine zinc (ZnPc) is an important class of photosensitizers. Derivatization of phthalocyanine ring with chemical functional groups provides anchor points for covalent attachment of biological targeting agents, thus increasing the selectivity of the photosensitizers. ZnPc with symmetric and multiple functional groups, e.g., tetracarboxyphthalocyanine zinc, is easy to be prepared but is unfavorable for linking targeting agents due to many reasons. On the other hand, single-substituted ZnPc, is more challenging to synthesize and, especially, to purify. Here we report the synthesis of an unsymmetrical phthalocyanine, 2-carboxyphthalocyanine zinc 1, with a single carboxylic group on phthalocyanine ring, and the design of its chromatographic purification.