Crystalline Self-Assembly into Monolayers of Folded Oligomers at the Air-Water Interface
作者:Kay Lederer、Adelheid Godt、Paul B. Howes、Kristian Kjaer、Jens Als-Nielsen、Meir Lahav、Gerhard Wegner、Leslie Leiserowitz、Isabelle Weissbuch
DOI:10.1002/1521-3765(20000616)6:12<2173::aid-chem2173>3.0.co;2-e
日期:2000.6.16
Insertion of the 1,3-bis(ethynylene)benzene unit as a rigid spacer into a linear alkyl chain, thus separating the two resulting stems by 9 A. induces chain folding at the air-water interface. These folded molecules self-assemble into crystalline monolayers at this interface, with the plane of the folding unit almost perpendicular to the water surface, as determined by synchrotron grazing-incidence X-ray diffraction. Three distinct molecular shapes, of the types U, inverted U, and M, were obtained in the two-dimensional crystalline state, depending upon the number of spacer units, and the number and position of the hydrophilic groups in the molecule. The molecules form ribbons with a higher crystal coherence in the direction of stacking between the molecular ribbons, and a lower coherence along the ribbon direction. A similar molecule, but with a spacer unit that imposes a 5 A separation between alkyl chains, yields the conventional herringbone arrangement.