Utilizing the Idenofluorene Scaffold to Access Stable and Tunable Diradicals
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Date
2020-09-24
Authors
Dressler, Justin
Journal Title
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Publisher
University of Oregon
Abstract
The concept of an organic molecule that possess two distinct radical centers yet is stable enough to be isolated and studied has intrigued chemists since the first reported diradical compound in 1904. In the last ten years the research of open-shell molecules has undergone a renaissance as chemists strive to get a fundamental understanding of the inherent electronic and magnetic properties that diradical polycyclic hydrocarbons (PCHs) display. The recent surge in reports of diradical PCHs is accredited to the development of new synthetic methods and spectroscopic techniques to fully characterize these unusual compounds. Although there has been an increase in the number of new diradicaloids there are very few reports in which structural modifications are made to a known diradical scaffold to tailor the properties towards the potential needs of industry. In this thesis I present studies in which we aim to produce series of open-shell compounds with moderate to good stability, with which we discover structure property connections to incrementally fine tune the singlet-triplet energy gap of a series of diradicals.
In Chapter I the Haley lab’s first foray into the field of diradicals along with a short introduction of diradical character is presented. The mentality and direction behind our groups work on diradicals in the last five years is also discussed. Chapter II describes the discovery of the second ever diradical reported by the Haley lab which possess a unique ground state triplet. Chapter III examines the synthesis of an uncommon open-shell compound named indenoindenodibenzothiophene (IIDBT) that was coined as a persistent singlet diradical. Chapter IV expands on the work done in the previous chapter and the singlet-triplet energy gap (ΔEST) is altered through molecule isomerism. Chapter V builds on the original synthesis of diindenoanthracene (DIAn) and a series of diradicals based on DIAn is synthesized to fine tune diradical character and ΔEST based on changes in bond order. In Chapter VI, late stage modification is used to modify the antiaromaticity and diradical character of indacenodibenzothiophenes (IDBT) and IIDBT derivatives, to impart meaningful change with less synthetic effort.
This dissertation contains previously published and unpublished coauthored material.