An efficient approach to the hydrolysis of 4-(ethoxycarbonyl)phenoxy-substituted boron subphthalocyanine

Two methods were tested to prepare a new boron subphthalocyanine containing six hydrophilic carboxyl groups. The first approach involved template cyclization and post-macrocyclization hydrolysis of ester groups of 4-(ethoxycarbonyl)phenoxy-substituted subphthalocyanine. Boron tribromide was chosen for the deprotection of the ester groups in subphthalocyanine due to the possibility of using mild reaction conditions. The second one is macrocyclization and hydrolysis in one pot. Water-soluble sodium salt of carboxy-substituted subphthalocyanine was prepared. The optical properties and thermal stability of the target subphthalocyanines were investigated.