Photophysics and Photochemistry of Heteroaryl Styryl Derivatives Inside Micelles

• Main Authors: Wei-Cheng Su, 蘇威丞
• Other Authors: Shun-Li Wang
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/84552091674291168093

碩士 === 國立嘉義大學 === 應用化學系研究所 === 101 === 2–styrylheteroaryl (2–StX–NMe2) derivatives possessing the intra-molecular charge transfer (ICT) ability were synthesized to study the influence of heteroaryl in photophysics and photochemistry. The first protonation site for 2–StX–NMe2 could occur at N,N–dimethyl group (donor) or at heteroaryl group (acceptor). For example, (1) 2–StID–NMe2: the first protonation site was on N,N–dimethylamino group, so a hypochromic shift on the absorption maxima was observed; (2) 2–StBOZ–NMe2 and 2–StBTZ–NMe2: the first protonation site located at N,N–dimethylamino group or the heteroaryl group, so one can observe two new peaks at the same time; (3) 2–StBIM–NMe2: a red-shift on the absorption maxima after protonation evidenced the first protonation site was occurred on pyrimidinyl group. The excited state basicity (pKa*) was decided by Föster cycle. The pKa* for 2–StID–NMe2 is -17.8 but the value of pKa* for 2–StBIM–NMe2 is 12.7. Therefore, the basicity of acceptor group increases after photoexcitation, but the basicity of donor group reduces in the excited state. When the concentration of TFA increases after monoprotonation, the absorption maxima of 2–StBOZ–NMe2, 2–StBTZ–NMe2 and IV 2–StBIM–NMe2 display bathchromic shift. The concentration of acid on the absorption maxima was called as homoconjugation effect. Trifluroethanol (TFE) shows a strongly influence to the excited-state reaction for 2–StX–NMe2 derivatives through hydrogen bonding. The hydrogen bonding in the ground state for 2–StBIM–NMe2 induced an excited-state proton transfer (ESPT) reaction. The chemical and photophysical reaction change for 2–StX–NMe2 derivatives inside micelles was studied in the last section. The chemical reactions for these sensors are influenced by the head charge of surfactants. The polarity inside various micelle were calculated through the emission maxima of sensor by comparing that of one in different mixed solution (1,4–dioxane and water). The polarity of micelle obtained by this method depends on the substituent hydophobicity of sensor. The polarity displayed by dielectric constant inside SDS is between 27 to 51, CTAB is between 23 to 40, and TX–100 is between 20 to 32. The measured basicity of sensor was also influence by the head charge of surfactants.