Synthesis and electrochemistry of soluble phthalocyanine complexes containing four peripheral dihexyl and dihexylhexylmalonate residues

Abstract

Tetrasubstituted phthalocyanines bearing four dihexylmalonate or dihexylhexylmalonate residues on the periphery (M[Pc(CH(COOC6H13)(2))(4)] or M[Pc(C(COOC6H13)(2)C6H13)(4)]; M = Pd(II), Cu(II), Co(II)) were synthesized from the anhydrous metal salts and the corresponding phthalonitriles. The complexes were only slightly soluble in polar solvents such as methanol and ethanol, but more soluble in less polar solvents such as benzene, toluene, and even hexane. The spectroscopic properties of the complexes were affected strongly by the electron withdrawing malonate units. Cyclic voltammetry on a platinum electrode in dichloromethane showed ligand-based one-electron transfers for Cu and Pd compounds, whereas the Co complex displayed metal-based or/and ligand-based one-electron transfers depending on the supporting electrolyte anion. The structures were confirmed by elemental analysis, H-1 NMR, C-13 NMR, IR, mass (EI and FAB), and UV/Vis spectroscopy.