Orientational organization of organic semiconductors within periodic nanoscale silica channels: modification of fluorophore photophysics through hierarchical self-assembly.

Smart nanomaterials: The orientational organization of small organic semiconductors (anthracene, in this case) within periodic nanoscale silica channels (see figure) is achieved through a novel hierarchical self-assembly approach. This elicits interesting optical effects and improved mechanical properties that could be of potential importance for functional materials.A novel hierarchical organic-inorganic self-assembly approach is proposed in driving the orientational organization of small organic semiconductors (anthracene, in this case). A cationic surfactant with the special organic semiconductor anthracene at the hydrophobic tail was synthesized and used as both the structure-directing agent and as functional nanobuilding blocks. The self-assembly procedure was rapid and allowed for the uniform and molecular-level controllable organization of the organic semiconductors within periodic nanoscale silica channels. A range of techniques were used to demonstrate that the photophysical and photochemical nature of anthracene is significantly altered in the inorganic host, consistent with orientational packing of the organic semiconductors and excimer formation within the channels, from which energy migration and significant emission occur. The nanocomposite has also been demonstrated to show an interesting selective sensor function with respect to small solvent molecules. We suggest that this method could be used to drive the assembly of a wide range of organic semiconductor guests, offering the development of a variety of useful, smart nanomaterials that are able to self-assemble in a controllable and robust fashion.