| Summary: | 碩士 === 國立成功大學 === 化學系碩博士班 === 100 === In the present work, UV absorber, 2-(2’-hydroxyl-5’-methylphenyl) benzotriazole (1), has been taken as the starting material to synthesize various derivatives such as 2-(2’-hydroxyl-5’-methyl-3’-nitrophenyl) benzotriazole (2), 2-(2’-hydroxyl-5’-methyl-3’-sulfonphenyl)benzotriazole (3), 2-(2’-hydroxyl-3’- methoxymethyl-5’-methylphenyl)benzotriazole (4), 2-(2’-hydroxyl- 3’-butoxy- methyl-5’-methylphenyl)benzotriazole (5) and 2-(2’-methoxy- 5’-methylphenyl) benzotriazole (6). Each of the derivatives was dissolved in hexane, cyclohexane, methanol and DMSO, respectively, to measure the photophysical properties (UV/Vis and Fluorescence). Spectroscopic study of UV/Vis absorption and fluorescence emission in solution state, and theoretical study with density functional theory (DFT) method were employed to characterize these UV absorbers. According to the results of UV absorption and fluorescence emission, it was found compounds with electron- withdrawing groups in the C-11 site could promote the strength of intramolecular hydrogen bonding and compounds (4,5) were capable of preventing from interacting with the solvent, which was due to the steric effect from bulkyl substituent in the C-11 site. By using molecular orbital analysis, it was found we can reasonably analyze that compounds(1)-(5) prefer intramolecular proton transfer in excited state (1) to (5) as to deactivate the excited state.
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