Synthesis of novel boron-coordinated fluorophores and the synthesis toward an ene-imine 1H-isoindole oligomer

Abstract

Nitrogen containing heterocycles are widely incorporated into small, conjugated molecules and extended π-systems that possess desirable properties for use in organic electronics (OE) and fluorescent dyes. Of particular interest is the ene-imine moiety, which is a critical component in porphyrin and boron-dipyrromethene (BODIPY) chromophores. BODIPYs are known for their intense fluorescence, small Stokes shifts, narrow optical bands, and large quantum yields. Despite the importance of the ene-imine motif, it is rarely observed outside of the aforementioned systems due to synthetic inaccessibility. Recent work has led to the synthesis of a new class of ene-imine bearing BODIPY-like fluorophores, the lactam BODAZAs (Boron-DiAZA-methene). Lactam BODAZAs possess large Stokes shifts, broad optical bands, and retain fluorescence in the solid state, all of which are rare feats for BODIPYs. This thesis details the expansion of the lactam BODAZA series using a generalized synthetic methodology and has resulted in the synthesis of two new lactam BODAZA fluorophores and the investigation of their optical properties. Recent advances in the development of ene-imine molecular building blocks have allowed for an investigation into the linear extension of the moiety via oligomerization. By tethering 1H-isoindole building blocks together, a linear conjugation pathway of ene-imine fragments can be produced and facilitate an investigation into the effect of conjugation length on the optical and electronic properties of the moiety. The synthesis toward an extended ene-imine conjugated system is detailed in this thesis.