Highly Ordered Monolayers of an Optically Active Amphiphilic Pyrene Derivative at the Air–Water Interface
Shigeru Negi, Mami Hamori, Hiroaki Kitagishi, Koji Kano
Abstract
Abstract To study the possibility of controlling molecular assemblies such as monolayers by using chirality, we synthesized 1-[1-(6-stearyl)pyrenyl]ethanol (SP6E), a novel amphiphilic molecule with a chiral center in the hydrophilic part and a pyrene ring in the long-chain alkyl backbone. The structures of racemic and optically active monolayers of SP6E were characterized using the π–A isotherm and analyzed by Brewster angle microscopy, surface fluorescence spectroscopy, and atomic force microscopy (AFM). The results showed that (±)-SP6E formed solid solution-like monolayers without any regular structure. By contrast, a one-dimensional columnar structure was observed in the (S)-(−)-SP6E monolayer by AFM, thereby confirming the formation of a relatively controlled monolayer structure. The successful structural control in (S)-(−)-SP6E is considered achieved through the cooperative effects of chirality and π–π stacking of the pyrene ring. Thus, this study demonstrates the possibility of controlling the structure and orientation of molecular assemblies by appropriately combining chirality and other intermolecular interactions based on molecular design. This approach is a promising strategy for developing surface materials and interfacial nanoarchitectonics with precisely controlled molecular orientations.