Coordination induced monolayer formation and fabrication of a novel conductive Langmuir-Schaefer film of benzimidazole-containing Schiff bases without a substituted alkyl chain

Two benzimidazole-containing Schiff bases: 2-[(2'-hydroxybenzylidene)amino]benzimidazole (HBA) and 2-[(2'-hydroxynaphthylmethylidene)amino]benzimidazole (HNA), which have no substituted long alkyl chain, have been found to form stable monolayers at the air-water interface when Ag(I) ions are present in the subphase. The monolayers can be further transferred onto solid substrates using the horizontal lifting method. The transferred films were characterized by UV-Vis absorption, X-ray photoelectron spectra (XPS) and X-ray diffraction. It has been found that monolayers were formed through the coordination between the benzimidazole moiety and Ag(I) ions. The transferred Langmuir-Schaefer (LS) films thus formed showed a relatively large conductivity in the order of 10(-1) S cm(-1). In addition, photoirradiation upon the film can cause a change in the conductivity.