Octakis(dodecyl)phthalocyanines: Influence of Peripheral versus Non-Peripheral Substitution on Synthetic Routes, Spectroscopy and Electrochemical Behaviour.

Non-peripherally octakis-substituted phthalocyanines (Pc's), MPc(CH) with M = 2H () or Zn (), as well as peripherally octakis-substituted phthalocyanines (Pc's) with M = Zn (), Mg () and 2H (), were synthesized by cyclotetramerization of 3,6- () or 4,5-bis(dodecyl)phthalonitrile (), template cyclotetramerization of precursor phthalonitriles in the presence of Zn or Mg, metal insertion into metal-free phthalocyanines, and removal of Mg or Zn from the phthalocyaninato coordination cavity. The more effective synthetic route towards Pc was demetalation of . Pc's were more soluble than Pc's. The Q-band λ of Pc's was red-shifted with ca. 18 nm, compared to that of Pc's. X-ray photoelectron spectroscopy (XPS) differentiated between N-H, N and N nitrogen atoms for metal-free phthalocyanines. Binding energies were ca. 399.6, 398.2 and 397.7 eV respectively. X-ray photoelectron spectroscopy (XPS) also showed zinc phthalocyanines and have four equivalent N and four equivalent N-Zn core nitrogens. In contrast, the Mg phthalocyanine has two sets of core N atoms. One set involves two N atoms strongly coordinated to Mg, while the other encompasses the two remaining N atoms that are weakly associated with Mg. Pc's , , and have cyclic voltammetry features consistent with dimerization to form [Pc][Pc] intermediates upon oxidation but Pc's and do not. Metalation of metal-free Pc's and Pc's shifted all redox potentials to lower values.