Synthesis of soluble rare-earth metal bisphthalocyanines and their Langmuir–Blodgett films for gas sensibility

In the present work, the synthesis of octa-4-(2,4-di-tert-pentylphenoxyl)-substituted rare-earth bisphthalocyanine with Sm, Er and Nd as central metal atom, respectively, is described. These compounds have improved solubility in organic solvents, and can form homogenous and relatively stable films at the air/water interface. The Langmuir film can be transferred by vertical dipping onto substrates with Z-type configuration. In Langmuir–Blodgett (LB) films, rare-earth bisphthalocyanine molecules exist mainly in associated species. The absorption increases linearly with the number of deposited layers indicating reproducible quality, and the layers adhere tenaciously to substrates and to each other. The gas sensibility of the films was investigated. The LB films of Sm and Er bisphthalocyanines have sensibility for the vapors of NH3 and NO2, but that of Nd bisphthalocyanine exhibits sensibility and selectivity only for the vapor of NH3.