Metal-ion sensing and aggregation studies on reactive phthalocyanines bearing soft-metal receptor moieties; synthesis, spectroscopy and electrochemistry

Tetrasubstituted metal-free {2H[Pc(S(CH₂)₆OCOC₄H₃S)₄]} and copperphthalocyanine {Cu[Pc(S(CH₂)₆OCOC₄H₃S)₄]}, bearing thiophene-2-carboxylate-hexylthio moieties, have been prepared as isomeric mixtures via cyclo-tetramerization. Both new compounds have been characterized by elemental analysis, FTIR, ¹H and ¹³C NMR, MS (Maldi-TOF) and UV-Vis spectral data. The cation binding abilities of the functional phthalocyanines with Ag^I, Pd^II, Hg^II, Pb^II and Cd^II are evaluated by a monomer-oligomer formation technique with UV-Vis spectroscopy. Spectroscopic properties of the complexes were affected strongly by the electron-donating sulfanyl units on the periphery. Cyclic voltammetry and differential pulse voltammetry studies show that both compounds give up to three ligand-based reduction processes and one ligand-based oxidation process having diffusion-controlled one-electron transfer properties.