Formation and study of thin films of tert-butyl-substituted thiopyrylium dyes

The formation of thin films of symmetrical and asymmetrical thiopyrylium dyes, containing tert-butyl substituents, on glass supports was studied. The films were deposited by centrifugation of solutions of individual dyes or dye-polymer [poly(methyl methacrylate)] compositions. The dye : polymer ratios necessary for the formation of WORM recording layers based on these dyes were determined. The use of a polymeric matrix increases the film thickness and optical density but decreases its reflection power and does not allow crystallization of the dye on the support to be completely avoided. An increase in the number of tert-butyl groups in the dye molecule prevents crystallization of the recording layer in the case of symmetrical dye molecules, but does not prevent it for asymmetrical molecules. The data obtained were interpreted in terms of geometrical views on the interaction of dye molecules in thin layers.