Effect of the Structure of Substituted Naphthalocyanines on Their Optical Properties in Thin Films

— The optical properties of 3,4,12,13,21,22,30,31-octa-(2-naphthyl)-2,3-naphthalocyaninato zinc and 3,4,12,13,21,22,30,31-octa-(2-naphthoxy)-2,3-naphthalocyaninato zinc in chloroform solutions and thin-film samples have been studied. Floating layers and Langmuir–Schaefer films are formed from these compounds. The absorption and fluorescence spectra are obtained for both solutions of compounds and multilayer Langmuir–Schaefer films. It is shown that the position of the Q band in the absorption spectra of the multilayered films, which is responsible for coloring of the compound, is bathochromically shifted by 12–13 nm as compared to the spectra of solutions. This can be explained by the presence of intermolecular dipole interactions between naphthalocyanine molecules oriented in the form of a chain, which are characteristic of J aggregates—one of known types of a structurally ordered formations of dye molecules. The fluorescence is quenched due to the formation of a densely packed boundary layer in thin-film samples.