DOI: 10.1002/chem.200802204 Orientational Organization of Organic Semiconductors within Periodic Nanoscale Silica Channels: Modification of Fluorophore Photophysics through Hierarchical Self-Assembly Le-Le Li, Hao Sun, Yan-Chun Bai, Chen-Jie Fang, and Chun-Hua Yan* [a] Introduction As we have learned from nature)s architectures, such as light-harvesting complexes in green plants, that spatial mo- lecular arrangements are important for controlling the direc- tion and efficiency of electron or energy transfer. [1] Inspired by such systems, control of supramolecular orientation and alignment has attracted considerable interest in the field of semiconductor materials, owing to the ability of supramolec- ular materials to control and tune charge-transport and energy-transfer processes. This has recently led to a new class of supramolecular materials for electronic and optoe- lectronic applications. [2–4] Of the many p-functional organic semiconductors employed in molecular materials, anthra- cene and its derivatives are among the most important kinds of semiconductors owing to their high oxidation potential, small p surface, and high fluorescence quantum yield; they have found applications ranging from light-emitting systems to biomolecular sensors. [5–9] It is generally recognized that the control of the supramolecular arrangement in terms of its shape and size is the key to success in such areas. Thus, much effort has been focused on the organization of these conjugated aromatics in the crystalline phase. [4–6, 10] Never- theless, the importance of inter- and intramolecular van der Waals interactions have received little attention for hier- archical hybrid supramolecular design beyond crystal ACHTUNGTRENNUNGengineering. [11–13] Surfactant-templated mesoporous materials [14, 15] have at- tracted considerable interest as hosts for the encapsulation of organic functionalities, resulting in composite materials with interesting optical properties and providing an interest- ing platform for novel technological applications. [16, 17] These host–guest materials not only offer new opportunities for controlling the local environments of occluded species, but also combine the high stability of the inorganic host system and a new structure-forming mechanism, owing to both their physical attributes and their simple bottom-up, solu- Abstract: A novel hierarchical organ- ic–inorganic self-assembly approach is proposed in driving the orientational organization of small organic semicon- ductors (anthracene, in this case). A cationic surfactant with the special or- ganic 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 organ- ization of the organic semiconductors within periodic nanoscale silica chan- nels. A range of techniques were used to demonstrate that the photophysical and photochemical nature of anthra- cene is significantly altered in the inor- ganic host, consistent with orientational packing of the organic semiconductors and excimer formation within the chan- nels, from which energy migration and significant emission occur. The nano- composite 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 con- trollable and robust fashion. Keywords: anthracene · mesopo- rous materials · optically active materials · organic–inorganic hybrid composites · self-assembly · semiconductors [a] L.-L. Li, H. Sun, Y.-C. Bai, Dr. C.-J. Fang, Prof.Dr. C.-H. Yan Beijing National Laboratory for Molecular Sciences State Key Laboratory of Rare Earth Materials Chemistry and Applications PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry Peking University, Beijing 100871 (P. R. China) Fax: (+ 86) 10-62754179 E-mail : yan@pku.edu.cn Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.200802204. # 2009 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim Chem. Eur. J. 2009, 15, 4716 – 4724 4716