Fabrication of Ultrathin Films of Liquid Crystals Assisted by (Octaalkoxyphthalocyanato)cobalt at the Air/Water Interface

Abstract

The generation of molecular films of hybrid liquid crystals (LCs) assisted by (octaeicosyloxyphthalocyanato)cobalt (C20PcCo) at the air/water interface is described. C20PcCo in a flat-laid orientation on a water surface has a space surrounded by the Pc ring plane and eight long-alkoxy chains as a wall so that hybrid molecular films are assembled by incorporating LC molecules due to hydrophobic interactions. Uniform molecular films are formed by spreading mixtures of C20PcCo and single-component LCs with hydrophobic terminal chains at subphase temperaures where LCs are in a nematic phase, while LCs bearing hydrophilic groups result in phase separation even in a nematic phase and give rise to no homogeneous hybrid molecular films. Homogeneous floating films of LCs were obtained even though the mixing ratio of C20PcCo:LC was 1:24, implying the multilayered structuring of LC molecules on a C20PcCo molecular sheet. Homeotropic orientation of guest LC molecules was suggested by using a liquid crystalline azobenzene.