Selective heavy metal receptor functional phthalocyanines bearing thiophenes: Synthesis, characterization, spectroscopy and electrochemistry

Soft metal ion receptor 2,9,16,23-tetrakis-6-(-thiophene-2-carboxylate)-hexylthio-phthlocyaninato zinc(II) and cobalt(II) complexes derived from 6-(3,4-dicyanophenylthio) hexylthiophene-2-carboxylate have been prepared as an isomeric mixture via cyclotetramerization reactions. The complexes have been fully characterized by elemental analysis, FTIR, 1H and 13C NMR, MS (ESI and MALDI-TOF) and by UV–vis spectral data. Soft metal ion binding ability of the complexes with AgI, PdII, HgII and CdII has been evaluated by UV–vis spectroscopic titration technique. Cyclic and differential pulse voltammetries show that while Zn(II)Pc gives up to two ligand-based reduction and one ligand-based oxidation processes having diffusion-controlled reversible electron transfer properties, Co(II)Pc represents one ligand-based and one metal-based oxidation and one metal-based and one ligand-based reduction processes having diffusion-controlled reversible electron transfer characters. Assignments of the redox couples of Co(II)Pc are confirmed by spectroelectrochemical measurements.