Abstract: The formation of stable Langmuir films on the aqueous AgNO3 subphase of 2-alkyl benzimidazoles (BzCn) with various chain lengths (from C5 to C15) and the layer structures of the transferred films were described. From the surface pressure-area isotherm, it has been found that the true monolayer could be formed for the short chain derivatives, while multilayer structures for the long ones. All of the Langmuir films could be transferred to solid substrate. The measurement of the UV spectra of the transferred LB films confirmed the coordination between benzimidazole group and Ag(I) ion in the Langmuir films. The effect of the length of alkyl chains on the structure of the transferred LB films was revealed by application of atomic force microscopy, FT-IR spectra and X-ray diffraction (XRD) measurement. It showed that except for BzC15, a regular layer structure was formed. Characterization of the morphology points to the formation of the neat LB film for the short derivatives and multilayer structure for BzC15.

Key words: LB films, Benzimidazole, AgNO₃, Layer structure