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This dissertation, "Design and Synthesis of Boron (III)-containing Dithienylethenes--from Multi-addressable and Gated Photochromism to Photoswitchable Luminescence Functions" by Chun-ting, Poon,, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: A series of photochromic dithienylethene-containing triarylboranes has been synthesized and characterized. The X-ray crystal structure of (4,5-bis(2,5-dimethylthiophen-3-yl)-thiophen-2-yl)dimesitylborane has been determined. An intense electronic absorption band was observed in all the triarylborane-containing compounds, corresponding to the intramolecular charge-transfer transition from the π-conjugated thiophene / fused thiophene / bithiophene to the vacant pπorbital of boron. This class of compounds was also found to bind fluoride ion such that the trigonal planar geometry of the boron center would be changed to tetrahedral, leading to a significant perturbation in the photophysical properties. Upon photo-excitation into the transition band, (4,5-bis(2,5-dimethylthiophen-3-yl)-thiophen-2-yl)dimesityl- borane and (4,5-bis-(2,5-dimethylthiophen-3-yl)-thieno[3,2-b]thiophen-2-yl)- dimesitylborane displayed multi-addressable photochromic reactivities upon addition of fluoride, in which a green solution was found in the closed form of the unbound compounds, while they changed to a purple color upon fluoride binding. Interestingly, both (4'',5''-bis(2,5-dimethyl-thiophen-3-yl)-2,2''- bithiophen-5-yl)dimesitylborane and (4'',5''-bis(2,5-dimethyl-thiophen-3-yl)-2,2''- bithiophen-3-yl)dimesitylborane displayed gated photochromic reactivities upon addition of fluoride, whil