Monolayer formation and Langmuir–Blodgett films of benzimidazole derivatives without alkyl chain

The monolayer formation and morphology of two benzimidazole derivatives, 2-phenylbenzimidazole (PhBz) and 2-(2′-pyridyl)benzimidazole (PyBz), which have no alkyl chains, have been investigated. These compounds can form monolayers on subphases containing concentrate AgNO3. No monolayers are formed on water or subphases containing other ions. Differences are found in the behaviors of the two compounds owing to the different hydrophilicity of the pyridyl and phenyl rings. Similar iceberg-like domains are observed in both the monolayers immediately after spread using a Brewster angle microscopy. The monolayers can be transferred onto solid substrates as X-type LB films. X-ray diffraction shows the regular layer structure of the LB films with long spacings of 1.19 and 1.33 nm for PhBz and PyBz, respectively.