Spectroscopic and structural characteristics of Langmuir–Blodgett films of bis[2,3,9,10,16,17,24,25-octakis(octyloxy)phthalocyaninato] rare earth complexes

The monolayer behavior of bis[2,3,9,10,16,17,24,25-octakis(octyloxy)phthalocyaninato] rare earth complexes M[Pc(OC8H17)8]2 (M = Eu, Dy, Er) at the air–water interface and their ordered molecular assemblies fabricated by Langmuir–Blodgett technique have been investigated by a series of techniques including surface pressure–area isotherms, electronic absorption spectra, polarized absorption spectra, low-angle X-ray diffraction patterns, and transmission electron microscope (TEM). The results indicated that bis(phthalocyaninato) rare earth molecules form well-ordered stable monolayers with a face-to-face configuration and edge-on arrangement to the water surface at the air–water interface and lamellar multilayers on solid substrates. The orientation angle of phthalocyanine rings with respect to the quartz plate surface in the Langmuir–Blodgett films has been determined to be 64.6°, 63.5°, and 63.3° for the Eu, Dy, and Er double-decker complexes, respectively, by the polarized absorption spectroscopy. High-resolution TEM reveals that a series of well-ordered rodlike aggregates of bis(phthalocyaninato) rare earth complexes, which can be considered as molecular cable arrays, were formed by self-organization in the monolayers.