Phthalocyanines (Pc) modified at eight positions with benzyloxyethoxy groups (CuPc(OC2OBz)8 and H2Pc(OC2OBz)8) form discotic mesophases in the bulk and self-assemble into cofacial rodlike aggregates in monolayers. These Pc aggregates form close packed arrays which are simple to process into highly coherent multilayer thin films. When these self-organizing molecular systems are compressed on the surface of an LB trough, the Pc columns align parallel to the compression barriers and form a rigid bilayer film (ca. 5.6 nm thick). Sections of these bilayer films can be mechanically removed from the trough surface with complete retention of integrity of the remaining film. This unprecedented behavior appears to arise from the multiple π−π interactions between adjacent Pcs, resulting in unusually strong noncovalent interactions. AFM and STM studies of monolayer and bilayer films show that they consist of Pc columns which are coherent over distances of 50−100 nm. Thin films consisting of up to 15 bilayers (ca. 84 nm) can be quickly built by a “mechanical stamping” process, and small-angle X-ray scattering characterization of these film materials confirms their unusual coherence. Large electrical and optical anisotropies are observed in multilayer films of CuPc(OC2OBz)8 and H2Pc(OC2OBz)8 which are comparable to those previously reported for thin film assemblies based on side-chain-modified silicon phthalocyanine polymers.

We review here the self-assembly, electrochemical and spectroelectrochemical properties of 2,3,9,10,16,17,23,24-octa(2-benzyloxyethoxy) phthalocyaninato copper ( CuPc ( OC 2 OBz )8), where terminal benzyl groups on the eight ethylene 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 analogue H 2 Pc ( OC 2 OBz )8 and similar copper and dihydrogen phthalocyanines with benzyl — terminated triethylene oxide substituents, CuPc (( OC 2 O )3 Bz )8, and H 2 Pc (( OC 2 O )3 Bz )8, which do not demonstrate the same degree of ordering 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 characterization of multilayer thin films. The oxidative electrochemistry of multilayer thin films prepared from these Pcs is strongly dependent on the chemical identity of the supporting electrolyte anion and on annealing of the thin films. Compliance of the films to counter-ion transport limits the extent of electrochemical doping. Preliminary studies of the oxidative electrochemistry of isolated CuPc ( OC 2 OBz )8 aggregates (diluted into an electroinactive methyl arachidate thin film) on an electroactive, integrated optic waveguide (EA-IOW) are also presented. Monitoring the change in absorbance at 633 nm on the waveguide surface allows the determination of the onset potential for oxidation of the isolated aggregates, which appears to be less positive in potential versus that observed for multilayer Pc assemblies.