Surface and Solution Mediated Studies of Small Molecule Enediyne Reactivity
Enediyne chemistry is a field with growing potential especially in the industries of material synthesis, catalysis, and therapeutic drug design. Enediynes offer a flexible synthetic handle with which to design these materials. However reactivity of enediynes is complex and in need of extensive and unambiguous characterization (Chapter 1). Imaging techniques like non-contact atomic force microscopy (nc-AFM) and scanning tunneling microscopy (STM) can be utilized for unambiguous determination of reaction products. Using, nc-AFM and STM, supported with ab initio density functional theory (DFT), we provide a glimpse into the reactive capabilities of enediynes and precisely characterize the complex product mixture from a reaction of 1,2-bis((2-ethynylphenyl)ethynyl)benzene (Chapter 2). Tailoring reaction conditions, including enediyne structure, can also result in tailoring the product of enediyne cyclization reactions. We characterize the chemical and electronic structure of individual chains of oligo-(E)-1,1’-bi(indenylidene), a poly-acetylene derivative that we have obtained through cooperative C1–C5 thermal enediyne cyclizations on Au(111) surfaces followed by a step-growth polymerization of the (E)-1,1’-bi(indenylidene) diradical intermediates (Chapter 3). These chemical transformations offer contrast to those from our initial investigation prompting a comprehensive study of the molecular energetics and conformational dynamics underlying these transformations. We report the detailed investigation of a surface-catalyzed cross-coupling and sequential cyclization cascade of 1,2-bis(2-ethynyl phenyl)ethyne on Ag(100) supported by theoretical simulations. These simulations indicate that the kinetic stabilization of experimentally observable intermediates is observably influenced by selective energy dissipation to the substrate and entropic changes associated with key transformations along the reaction pathway (Chapter 4). Finally, we begin to build on a motif by which to synthesize one-dimensional materials using the reactivity lessons learned from surface studies of enediynes. Synthesis of new small molecule enediynes is discussed, the thermodynamics of Bergman cyclization is considered and evaluated, and polymers are synthesized using Bergman Cyclization Polymerization (BCP) (Chapter 5).