Synthesis of Materials with Self-Ordering Chiral Macromolecules

Abstract

The present work focuses on chirality, functionalization, and molecular shape to establish links between molecular architecture and the spatial organization of polymer chains in organic materials. The approach used was to synthesize chiral and racemic homologous polymers exhibiting a preference for extended chain conformations and having the strongly dipolar cyano group as a substituent of the stereogenic center. The strong dipole moment at the chiral center offered potential to combine strong long-range forces with chiral recognition. Electron and optical microscopies were our selected tools to probe three-dimensional structures, and nonlinear optics was used to measure the properties of the materials obtained. We found that the relative stereochemistry of the repeat unit dipole impacts significantly on global chain symmetry and its packing mode. Enantiomeric enrichment of chains changed hexagonally packed cylindrical molecules to board-like molecules which pack edge-to-edge in an orthorhombic lattice. Interestingly, enantiomeric enrichment of chains enhanced the second-order nonlinear optical susceptibility of films prepared from these macromolecules.