Molecular assembly and photophysical properties of Langmuir-Blodgett films with novel lanthanide complexes of long chain para-dodecanoyl and para-myristoyl oxybenzoate

Several ultrathin luminescent Langmuir-Blodgett (LB) films have been prepared by using the subphase containing the rare earth ions (Eu3+, Dy3+). The effect of the rare earth ions on the monolayer of p-dodecanoyloxybenzoate (12-OBA) and p-myristoyloxybenzoate (14-OBA) was investigated. IR spectra showed the rare earth ions were bound to the carboxylic acid head groups and the coordination took place between the polar head group and the rare earth ions. The layer structure of the LB films was demonstrated by low-angle X-ray diffraction. The AFM study revealed that the LB films were uniform and crack free, and the films mainly consisted of closely packed grains with an average size of 241 nm. The LB films can give off strong fluorescence, and the signal can be detected from a single layer. The characteristic luminescence behaviors of LB films have been discussed compared with those of the complexes.