Synthesis and Characterization of Electronically Labile Molecules

Abstract

Valence tautomers are molecules that change electronic states as a function of an external stimulus such as temperature, pressure and light. The purpose of the dissertation research has been to explore different aspects of the behavior of valence tautomeric molecules. The research work is divided into three exploratory avenues: 1) Intermolecular contributions to the behavior of surface-confined valence tautomers, 2) the effects of structural changes to the intramolecular coupling in dinuclear valence tautomeric systems, and 3) the synthetic control of the intramolecular delocalization of the semiquinonate-catecholate donor-acceptor pair. For the first project it was discovered that intermolecular interactions in surface-confined valence tautomers change the thermodynamic parameters of the valence tautomeric conversion. The second project yielded results that conclusively demonstrated that large spin-density distribution on the ligands of valence tautomers and small through-bond distance between valence tautomeric centers are necessary in order to electronically couple multinuclear valence tautomers. Finally, it was shown that it is possible to synthetically control the delocalization of the semiquinate-catecholate donor-acceptor pair of the low-temperature mixed-valent valence tautomeric state by substituting the bipyridine counterligand with different functional groups.