Inclusion of liquid crystalline azo-dyes in nanometric porous anodic aluminas: A comparative morphological and optical study

Prepared amorphous porous anodic alumina with average nanometric porous dimensions of 67 nm in diameter and 50 μm in depth was successfully used as host network for different liquid crystalline azobenzene compounds bearing oligo(ethylene glycol) segments. Since the implemented optical chromophores were specifically designed for quadratic non-linear optical applications, the obtained ordered hybrid structures were fully characterized according to the second harmonic generation technique following the Maker-Fringes method. Comparative linear optical absorption, Raman and X-ray photoelectron spectroscopic investigations were also carried out in order to evaluate the optical performance of these molecular systems within the 1D-nanotube-like confinement. Finally, atomic force microscopic studies of both the dissolved barrier layer and the porous cap were performed on the samples in order to explore surface morphology and assure best possible insertion of these azo-dyes within the pores of anodic alumina.