Substituent effects in soluble phthalocyaninatoiron(II) complexes

Abstract

The synthesis and characterization of 1,4- and 2,3-octa- and tetra-substituted bis(tert-butylisocyanide)phthalocyaninatoiron(II) complexes with linear (n-heptyl, n-octyloxy) and branched (2-ethylhexyloxy) chains are reported. Analytical, spectroscopic and electrochemical studies have been carried out to obtain an insight into the substituent effects of these compounds. ¹H NMR spectroscopy shows a smaller upfield shift of the axial ligand protons for the 1,4-substituted systems than for the 2,3-substituted systems. In the UV–VIS spectra bathochromic shifts are observed for the systems with their side chains in 1,4-positions in comparison with the 2,3-substituted analogues. Cyclic voltammetric measurements were carried out in dichloromethane and pyridine to determine the redox potentials of these complexes. A decrease of the oxidation and an increase of the reduction potentials were found by introducing substituents in the 1,4-positions of the macrocycle. 1,4-Substitution perturbs the electronic structure of phthalocyanine ring systems to a larger extent than 2,3-substitution.