Supramolecular chirality at the air/water interface [Invited]

Second Harmonic Generation (SHG) was used to study the nonlinear optical properties of a two-dimensional film formed by the achiral amphiphilic compound 5-(octadecyloxy)-2-(2-thiazolylazo) phenol (TARC18) at the air-water interface. The S-polarized SHG intensity was measured as a function of the incident fundamental wave polarization angle during the monolayer compression. The method was applied to follow the emergence of chirality during the film compression and at constant surface pressure. The formation of molecular aggregates revealing supramolecular chirality was then demonstrated. It was shown furthermore that the origin of chirality was dominated by the magnetic contributions. (C) 2011 Optical Society of America