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theses

The functionalization of π-conjugated polycyclic aromatic hydrocarbons (PAHs) with main group elements (i.e., B, Si, P) has been a topic of intense interest over the past several years. Especially conjugated organoboron compounds have attracted considerable attention owing to their unusual optical and electronic properties. Recently, tetra-coordinated organoboron compounds have attracted increasing attention for applications in organic field effect transistors (OFETs), organic light emitting diodes (OLEDs), solar cells, sensory and biological imaging materials, and as photoresponsive materials. This dissertation focuses on the investigation of the effects of the B-N Lewis pair functionalization on larger π-conjugated scaffolds based on anthracene. Several new types of BN-substituted anthracenes were targeted as new low band gap materials for use as optoelectronic materials, as well as for singlet oxygen uptake and release applications.

We developed a new class of B-N functionalized PAHs by electrophilic aromatic borylation of pyridylanthracenes. The formation of B-N Lewis pairs at the periphery of anthracene results in unique structural features and electronic properties. In addition, we discovered that the BN-fused anthracenes undergo self-sensitized uptake of singlet oxygen and subsequent controlled release by thermolysis. The controlled capture/release of singlet oxygen opens the possibility for applications in photodynamic therapy (PDT) and sensing.

In continuation of this work, we investigated the effects of substituents on the structural features and electronic properties. A series of BN-fused dipyridylanthracenes with Me groups in different positions of the pyridyl rings were synthesized. The results suggest that minor structural modifications on the pyridyl moiety can alter dramatically the reactivity of the BN-anthracenes, which can be exploited for applications as singlet oxygen sensitizers on one hand and materials for delivery of singlet oxygen on demand on the other hand.

To achieve a further decrease in the band gap of BN Lewis pair-functionalized PAHs, we designed the borane-modified dianthracenylpyrazine derivatives. DFT calculations indicated that BN-fused dianthracenylpyrazine compounds show a large decrease in the HOMO-LUMO gap compared to the previously described BN-fused dipyridylanthracenes. The B-N doped polycyclic species have significant absorbance at greater than 700 nm. Thus, the attachment of BN Lewis pairs to PAHs is also a promising strategy toward low band gap materials.

ETD_10393

Ph.D.

Includes bibliographical references

doi:10.7282/t3-4q2d-kf12

ETD doctoral

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