Chiral supramolecular assemblies from some achiral Schiff bases without alkyl chain through the organization at the air/water interface

Two novel Schiff bases, 1-benzthiazolyliminomethyl-2-naphthol (TSN) and 1-(6′-chlorobenzthiazolyliminomethyl)-2-naphthol (ClTSN), were synthesized and their molecualr assemblies at the air/water interface were investigated. Both of the compounds could be spread on water surface although they have no alkyl chains. The Schiff base molecules formed J- or H-aggregate in the Langmuir–Schaefer (LS) films transferred from water surface. In AFM, a multilayer film formation was observed. It is interesting to note that the LS films of achiral TSN and ClTSN transferred from water surface showed chirality. The supramolecular chirality in these LS films was suggested to be due to a cooperative stereoregular π–π stacking of the functional groups in a helical sense.