QUINOIDAL OLIGO(9, 10-ANTHRYL) HYDROCARBONS WITH TUNABLE GROUND STATES AND METASTABLE EXCITED STATES

Abstract

Diradicaloids are molecules with partial electronic occupation of their lowest unoccupied natural orbital (LUNO). Diradicaloids are interesting materials due to their unique optical, electronic and magnetic properties. Their diradical character can be controlled through steric manipulation of the chemical structure and/or electron density manipulation. A good example is the quinoidal oligo(9,10-anthryl)s. These quinoidal polycyclic hydrocarbons are pro-aromatic systems with addition of aromatic rings in the closed-shell quinoidal form. However, the steric repulsion of the anthryl units contorts the structure of the molecule towards the more flexible open-shell form. This balance of aromatic stabilization and steric repulsion plays a critical role in determining the ground state of the quinoidal oligo(9,10-anthryl)s. In this thesis project, we will look at the structure-property relationship between the opposing stabilization forces and how this delicate balance can be influenced to create new novel materials with interesting properties (e.g. stimuli sensitivity, chromism etc).