N^N- and N^C Chelate Four-Coordinate Organoboron Compounds: Synthesis, Properties and Applications
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This thesis concerns the synthesis of N^N- and N^C-chelate four coordinate organoboron compounds and the investigation of their photophysical and photochemical properties. The preparation of a novel BODIPY derivative possessing unusual dual emissive property has been accomplished. The origin of the dual emission was determined through a detailed investigation. The use of the new BODIPY compound as a highly effective surface ligand for achieving highly uniform and monodispersed PbS nanoparticles has been demonstrated. Electronic communication between BODIPY ligands at the nanoparticle surface and the PbS core has also been established. The incorporation of BODIPY-bearing PbS nanoparticles into a simple photovoltaic device was shown to enhance the device’s performance. The preparation of two new BODIPY molecules decorated with either BMes2(vinyl) units or N^C-chelate boryl units has been achieved. Substitution at the meso or the 2,6-positions of the BODIPY core resulted in a significant shift of the emission energy with respect to that of the parent compound. In contrast, replacement of the fluorine substituents with BMes2-vinyl or B(ppy)Mes2-alkynyl groups did not affect the emission wavelength. Both molecules exhibited excellent photophysical properties in solution and the solid state. The BMes2(vinyl) unit greatly enhances BODIPY fluorescence efficiency in a PMMA matrix. Meanwhile, the photoreactivity of the N^C-chelate boryl unit is switched off completely by the BODIPY ligand via intramolecular energy transfer. A new class of N^C-chelate organoboron compounds have been synthesized. This class of compounds has been found to display unprecedented photo-reactivity, namely, photo-elimination reactions, which enabled the synthesis of new B-N substituted phenanthrene compounds in high conversion yields. The new B-N substituted phenanthrene compounds exhibited excellent absorptive and emissive properties with potential applications in optoelectronic devices.