Abstract
Accumulated Langmuir−Blodgett (LB) films that consist of two layers of barbituric acid (BA) and triaminotriazine (TAZ) derivatives (C18BA and 2C18TAZ) were deposited at various surface pressures on a gold-evaporated glass slide covered with a deuterated cadmium stearate (CdSt-d 35) monolayer. The two-monolayer LB films (the CdSt-d 35 layer is considered to be a part of the substrate) were measured by infrared reflection−absorption (IRRA) spectrometry to investigate the hydrogen-bonding network formed between the two layers. The most notable results were given by the LB film that has the layer configuration of IR//C18BA/2C18TAZ/CdSt-d 35/Au. The C18BA layer was deposited at various surface pressures on the 2C18TAZ monolayer. Depending on the surface pressure, the wavenumber of the CO stretching vibration band (ν(CO)), derived from BA, showed drastic change. At 20 mN m-1, the CO groups were found to be in non-hydrogen bonded state (1755 cm-1) to a large extent. The non-hydrogen bonded CO groups are, in general, rarely seen for the interacted BA/TAZ system. The extraordinary non-hydrogen bonded CO groups were explained readily by a novel schematic model that was estimated through the molecular orientational analysis. In consequent, the film-to-film interaction is found to give a quite unique hydrogen bonding network structure.
