Interfacial assembly of a series of trigonal Schiff base amphiphiles in organized molecular films

A new series of trigonal Schiff base amphiphiles with symmetric aromatic cores and different substituted headgroups were designed and their interfacial assemblies were investigated. When on the metal ions subphases, an in situ coordination can occur for all compounds. The coordinated films could be transferred onto solid substrates and subsequently characterized by various spectroscopic methods such as UV–vis and Fourier infrared spectra as well as the morphological characterization with atomic force microscopy measurement. In addition, on acidic or alkaline subphases with different pH values, the interfacial behaviors and morphologies changed obviously due to the dissociation of the phenol group at alkaline subphase and protonation of the azomethine at strong acidic subphase. Depending on the trigonal molecular structures and different substituted headgroups, these amphiphiles showed distinct assembly behaviors in the organized molecular films. At the same time, a rational explanation about the influence of molecular structures and headgroups on regulating the assembly behaviors was proposed.

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► Some trigonal amphiphiles with different substituted headgroups are synthesized.
► These amphiphiles showed obvious headgroup effect in the LB films.
► On acidic or alkaline subphases, the interfacial behaviors changed obviously.