Floating layers and thin films of mesogenic mix-substituted phthalocyanine holmium complex

Abstract

The supramolecular organization of the A3B-type phthalocyanine holmium complex (A3B–Ho) was investigated in floating layers at the air–water interface and in Langmuir-Schaefer thin films at the air–solid interface. The floating layers formed under different experimental conditions on the water subphase using the Langmuir technique. They were studied by Brewster angle microscopy, grazing incidence X-ray diffraction and X-ray reflectometry. It was established that molecules of A3B–Ho form stable ordered floating monolayer on the water surface. Experimental conditions required for this monolayer formation were determined as following: the initial degree of coating of the water surface was 18%, the compression rate of barriers was 6 cm2/min and the surface pressure was 0.4 mN/m. Under these conditions a stable crystalline monolayer structure was obtained with an area per one molecule 3.9 nm2. It has a two-dimensional face-on packing with the intralayer period of 2.06 nm. The Langmuir-Schaefer thin film was obtained on the basis of the above mentioned monomolecular floating layer. The film possesses a single two-dimensional structure with the packing of the molecules parralel to the substrate surface that was revealed by electron diffraction. The lattice parameters of the monomolecular film were a = 1.65 nm, b = 1.92 nm, γ1 = 75. It was shown that the film preserves the structure of the floating monolayer.