Langmuir, Vol.16, No.22, 8390-8395, 2000
Fabrication of ultrathin films of liquid crystals assisted by (octaalkoxyphthalocyanato)cobalt at the air/water interface
The generation of molecular films of hybrid liquid crystals (LCs) assisted by (octaeicosyloxyphthalo-cyanato)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 temperatures 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.