Preperation and Characterization of N-Alkylbipyridinium Salt-Phthalocyanine Adduct LB Film

Abstract

Hexa-coordinate iron phthalocyanines were synthesized to prepare stable monolayers and highly oriented. Langmuir-Blodgett (LB) films. Monolayer of [{ N-docosyJ-4, 4'-bipyr idinium (1+)-N'} (pyridine) (phthalocyaninato)iron (II)] bromide [2] was formed at air-water interface and was depo sited onto a substrate as a Z-type film by vertidal lifting method, whereas LB film could not be obtained in the case of bis(pyridine)(phthalocyaninato)iron(II) [1] without long alkyl chains. From the X-ray diffraction measurement of [2] LB film, the d-spacing was 37±2A. From this, phthalocyanine rings were considered to be inclined at ca. 35 degrees against substrate. This result was in good agreement with those of polarized infrared absorption measurement and zero-bressureextrapolated area of π-A isotherm. These results also suggested overlap of phthalocyanine rings in LB film. The [2] LB film showed large anisotropy in electric conduction. that is, the conductivity along the direction parallel to the substrate was 10^-7±2S/cm, whereas that along the perpendicular direction was less than 10^-12S/cm. The conductivity along the parallel direction is higher than that of iron phthalocyanine and is comparable to those of one dimensional phthalocyanine-ligand polymers. This increase of conductivity is considered to be caused by the formation of π-orbital overlap of phthalocyanine rings to increase the conductivity.