The thermodynamic concept was introduced in order to elucidate the dynamic flexibility of the amide derivative of p-phenylenediacrylic acid “1” for the formation of its monolayer. The phase transition region appeared in the surface pressure - area isotherms was interpreted in terms of molecular comformational changes between two extreme forms; bent comformation and erect comformation. The LB films prepared at higher temperatures possessed highly oriented and closely packed molecular assembly, as revealed by means of spectroscopy. Even though, the LB films prepared at lower temperatures exhibited a higher photoreactivity.