In the past few decades, people tried many times to make the bulk materials to possess the same properties as the underlying molecular functionalities. However, it was not successful in many cases. It turns out the key factors for controlling the bulk material properties are not only the molecular chemical functionalities, but also the physical structures that can transfer and amplify these functions. It is evident that hierarchical structures constructed by Janus building blocks play an important role in transferring the molecular information from primary structure to 3D supramolecular structures across different length scales. The objective of this research is to design and develop functional hybrid materials with novel hierarchical structures and exceptional properties based on well-defined geometrically and chemically asymmetric building blocks. The transferring of molecular information from the primary molecular structure to three dimensional hierarchical structures was studied.
Two projects related to the hierarchical structure determination of shape and interaction amphiphile molecules are discussed through thermal analysis and diffraction methods. The first project discusses polyhedral oligomeric silsesquioxane (POSS) and [60]fullerene conjugated molecule (POSS-C60). Crystals of the insulator-conductor dyad exhibited polymorphism with two different crystal structures: an orthorhombic and a hexagonal unit cell with P21212 and P6 cell symmetry, respectively. The crystals are ideal for electronic applications because of the conductive fullerene layers between insulating POSS layers. The second project reveals the supramolecular structure of an amphiphilic Janus bisamide. The molecular information was transferred to macroscopic length scale through three levels hierarchical structure. Three ordered phases attributed to intermolecular hydrogen bonding were identified and characterized, including a phase-separated columnar LC phase, a metastable crystalline phase, and a stable 3D ordered monoclinic crystal phase that can be obtained through isothermal annealing. The results provided a new approach of fine-tuning not only in the Janus supramolecular structures but also in the formation pathway of the self-assembling process in order to meet the specific requirements for optical and biological applications.