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

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-C6H13OH)(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 Pd2+. Thio donors of the complexes coordinate to Ag+ and Pd2+ 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 pi-orbital interactions between the rings of the sandwich. The newly synthesized compounds have been characterized by elemental analysis, FTIR, H-1 and C-13 NMR, MS (ESI and MALDI-TOF), UV-vis and EPR spectral data. Copyright (c) 2006 Society of Porphyrins & Phthalocyanines.