DFT studies on 3-hydroxyflavone, 2-phenylbenzoxazole and photoinduced borylation

Abstract

This thesis explains the anti-kasha effect and supramolecular chemistry of 3-hydroxyflavone, the aggregation induces emission enhancement of 2-phenylbenzoxazole, and the photoinduced borylation.

For 3-hydroxyflavone, the excitation wavelength affected the ratio of normal form to tautomer form. Such a performance violates Kasha’s rule. By excited state calculation, another structure in higher excited state was optimized and that state was proposed for proton transfer. Three supramolecular hosts were selected to enhance the fluorescence intensity in aqueous medium. The Our own N-layered Integrated molecular Orbital and molecular Mechanics (ONIOM) approach was adopted to find out the preferred supramolecular interaction. After understanding the interaction, the difference in ratio of tautomer form to normal form would be explained.

For 2-phenylbenzoxazole, OMIOM was used to model the aggregate phase and PCM model was used to model the solution phase. The internal charge transfer and twisted intramolecular charge transfer were compared in the solution phase and aggregate phase. The computed fluorescence closely matches with the experiment.

The photoinduced borylation is to compare the mechanism of bis(catecholato)diboron and bis(pinacolato)diboron with the N-hydroxyphthalimide ester. By experiment in the literature, bis(catecholato)diboron preferred electron donor acceptor complex pathway and bis(pinacolato)diboron preferred quenching by triplet state. The thesis explained the difference and calculated the energy profile of the mechanism.