Conjugated Materials from Olefinic Building Blocks

This thesis describes the synthesis of new cyclic and linear olefinic oligomers and studies on their structure-property relationships for molecular electronic applications. In Chapter 2, a new family of cyclic stilbene oligomers is introduced. The stereoselective synthesis of two cyclostilbenes and the mechanism are discussed. These cyclostilbenes emit blue light with high fluorescence quantum yields and form channel architectures in the solid state that can be filled with guest molecules. In Chapter 3, a new method of tuning rectification in single molecule diodes with a stilbene backbone and asymmetric linker groups is explored. We demonstrate through single-molecule current-voltage measurements that the rectification ratio can be predictably and efficiently tuned. This result constitutes the first experimental demonstration of a rationally tunable system of single-molecule rectifiers. In Chapter 4, a combined intra- to intermolecular mechanism for singlet fission in a tunable class of oligoenes is discussed. The versatility of chemical modification in this system can allow us to fine-tune energetic alignment as well as the crystal stacking motifs. Finally, attempts to create a more efficient family of donor-acceptor type intramolecular SF materials with longer triplet lifetimes are described. This study gives insight into the competition between singlet fission and intersystem crossing processes, which can both be mediated by a charge transfer state.