Functional alcohol-soluble double-decker phthalocyanines: synthesis, characterization, electrochemistry and peripheral metal ion binding

Abstract

In this study we report the preparation, physical characterization and electrochemistry of peripherally functionalized substituted ionophore double-decker lanthanide phthalocyanines, lanthanide bis-[(4,4″,4″,4‴)-tetrakis-(6-hydroxyhexylthio)phthalocyaninates], { M [ Pc ( S - C 6 H 13 OH )4]2} ( M = Pr III, Yb III, and Lu III). All benzenes on the double-decker phthalocyanines are functionalized with hydroxyhexylsulfanyl moieties for potential use as metal ion binding and surface anchors. The double-decker phthalocyanines synthesized from the anhydrous metal salts { Ln ( acac )3} and the corresponding 4-(6-hydroxyhexylthio)-1,2-dicyanobenzene exhibit ion-specific optical changes in the presence of Ag + and Pd 2+. Thio donors of the complexes coordinate to Ag + and Pd 2+ to give 4:1 metal-phthalocyanine complexes. Newly synthesized lanthanide double-decker phthalocyanines are soluble in methanol ( MeOH ), ethanol ( EtOH ), tetrahydrofuran ( THF ), dimethylformamide ( DMF ), dimethylsulfoxide ( DMSO ), chloronapthalene, quinoline and less soluble in i- PrOH and acetonitrile. Electrochemical studies reveal that all lanthanide-base complexes undergo ligand-based redox processes. The smaller HOMO-LUMO gaps of the complexes indicate the existence of strong π-orbital interactions between the rings of the sandwich. The newly synthesized compounds have been characterized by elemental analysis, FTIR, 1H and 13 C NMR, MS (ESI and Maldi-TOF), UV-vis and EPR spectral data.