Electron Rich Cobaltocenium Derivatives as Tunable Mechanophores for Mechanochemistry

In this dissertation, metallocene-containing polymers are investigated and probed for tunability in mechanochemistry. These metallocene moieties are experimentally and computationally characterized. In chapter 1, relevant background and recent developments of metallocene-containing polymers are discussed. Additionally, the field of mechanochemistry is briefly introduced including applications and future directions within the field. In chapter 2, design and synthesis of these metallocene-containing polyelectrolytes via ring opening metathesis polymerization (ROMP) are outlined. These polymers then undergo mechanophore activation via ultrasonication and relevant analysis and characterization of polymers both before and after ultrasonication are detailed. These polymers are comprised of differing electron donating substituents on the metallocene moiety as well as associated counterions. These metallocene derivates are designed in order to evaluate effects of electron donating groups (EDG) and counterions on mechanical strength in respects to cobaltocenium mechanophores. In chapter 3, computational modeling of these organometallic polymers are outlined with specific emphasis on the dissociation mechanism of the metallocene complex. These computational modeling techniques include geometry optimization and constrained geometries simulate exterinal force (CoGEF) methods. These computationally modeled polymers include metallocenes with methyl and t-butyl substituents on the cobaltocenium moieties. Additionally, the counterion associated with the cationic metallocene are altered between chloride (Cl-) and hexafluorophosphate (PF6-) when modeling these polymers. This provides easy investigation into the impacts that these alterations have on the mechanophore structure evolution during the heterolytic dissociation. In chapter 4, a summary of this dissertation as well as outlook and future research is provided.