Formation and spectroelectrochemical characterization of multilayer and submonolayer thin films of 2,3,9,10,16,17,23,24-octa(2-benzyloxyethoxy) phthalocyninato copper (CuPc(OC(2)OBz)(8))

We review here the self-assembly, electrochemical and spectroelectrochemica l properties of 2,3,9,10,16,17,23,24-octa(2-benzyloxyethoxy) phthalocyanina to copper (CuPc(OC(2)OBz)(8)), where terminal benzyl groups on the eight et hylene oxide side chains assist in forming unusually ordered, mechanically rigid thin films. New spectroscopic characterization of cast CuPc(OC(2)OBz) (8) films is discussed in comparison with cast films of its metal-free anal ogue H2Pc(OC(2)OBz)(8) and similar copper and dihydrogen phthalocyanines wi th benzyl- terminated triethylene oxide substituents, CuPc((OC2O)(3)Bz)(8), and H2Pc((OC2O)(3)Bz)(8), which do not demonstrate the same degree of orde ring as CuPc(OC(2)OBz)(8). AFM studies of horizontally transferred LB films of CuPc(OC(2)OBz)(8) show column-column distances of ca 2.8 nm and confirm the high degree of ordering previously surmised from spectroscopic charact erization of multilayer thin films. The oxidative electrochemistry of multi layer thin films prepared from these Pcs is strongly dependent on the chemi cal identity of the supporting electrolyte anion and on annealing of the th in films. Compliance of the films to counter-ion transport limits the exten t of electrochemical doping. Preliminary studies of the oxidative electroch emistry of isolated CuPc(OC(2)OBz)(8) aggregates (diluted into an electroin active methyl arachidate thin film) on an electroactive, integrated optic w aveguide (EA-IOW) are also presented. Monitoring the change in absorbance a t 633 nm on the waveguide surface allows the determination of the onset pot ential for oxidation of the isolated aggregates, which appears to be less p ositive in potential versus that observed for multilayer Pc assemblies. Cop yright (C) 1999 John Wiley & Sons, Ltd.