Chiral assemblies of achiral rigid-flexible molecules at the air/water interface induced by silver(I) coordination

Chiral films are obtained from achiral rigid-flexible molecules. Due to hydrogen bonding and steric constraints, these molecules can self-assemble into chiral assemblies at the air/water interface upon compression. When the molecules are spread on a subphase containing AgNO(3), they form a stable monolayer through coordination with Ag(I) ions, as confirmed by surface pressure-area isotherms, UV/Vis and FTIR spectroscopy, and AFM. More interestingly, macroscopic chirality was detected in the Ag(I)-coordinated films by circular dichroism measurements. The formation mechanisms of the two kinds of chiral films are briefly discussed.