芳香族雙氧烷化學發光的取代基效應
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2013
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4個三環1,2-雙氧烷衍生物1a~4a是由對應結構之1,4-雙醚苊烯化合物1~4在二氯甲烷中與單態氧進行環化加成而成。本論文將這些化合物分成2個部分加以討論。第一部分包含1,2-雙氧烷化合物1a~3a的熱分解，探討在5號苊環位置供電子能力的取代基效應。實驗證據顯示1,2-雙氧烷化合物1a~3a分別經由熱分解形成電子激發態雙酯化合物1b*~ 3b*並伴隨化學發光。由高張力1,2-雙氧烷環之扭曲立體結構自發斷裂氧-氧鍵及碳-碳鍵，產生電子激發態雙酯化合物並伴隨化學發光。觀察化合物2a的化學發光光譜相較於化合物1a及3a更為紅位移，推測由於具電子供給特性之甲氧基造成激發態更高之穩定性。此外，溶劑效應的研究顯示化合物2b呈現更極性的激發態使光激螢光光譜之明顯紅位移。1,2-雙氧烷的熱分解動力學研究，清楚顯示化合物2a的化學發光特性明顯與化合物1a和3a有所不同，這些結果顯示化合物2a的供電子取代基能活化分子內化激電子互換發光機制。
第二部分研究化合物1a與5-鹵取代1,2-雙氧烷化合物3a及4a在化學發光螢光及磷光的重原子效應。當化合物3a及4a在二氯甲烷溶劑中，升溫範圍由313至353K，經熱分解形成對應之萘基雙酯化合物3b及4b時，可產生化學發光磷光與螢光。由艾林線性圖求得之活化焓，顯示重原子效應增加1,2-雙氧烷化合物熱分解的叁態化學激發過程產生磷光的路徑。
Four tricyclic 1,2-dioxetane derivatives, 1a-4a, were synthesized from their corresponding 1,4-dioxin acenaphthylene compounds, 1-4, by reaction with singlet-oxygen (1O2) in dichloromethane. The first part which involves the thermal decomposition of the compounds 1a-3a illustrates the substituent effect on the ability of the electron donating at 5-position of “acenaphtho” moiety. Evidence for formation of the dioxetanes ,1a-3a, is the chemiluminescence that corresponds to the emission from the electronically excited diesters 1b*-3b*, which are decomposed thermally from the dioxetanes 1a-3a, respectively. The highly strained 1,2-dioxetane ring decomposes from a twisted geometry by simultaneous cleavages of the O-O and C-C bonds producing the electronically excited diester that emits chemiluminescence (CL). It was observed that the CL from compound 2a is dramatically red-shifted relative to that of compounds 1a and 3a suggesting a higher degree of stabilization of the excited state by the electron donating methoxy group. Also, a study of the solvent effect on the fluorescence shows a significant red-shift in compound 2b, indicating a more polar excited state. The kinetics of the thermal decomposition of the 1,2-dioxetanes clearly demonstrate that the chemiluminescence characteristics of the compound 2a is quite different from that of compounds, 1a and 3a. These results are consistent with the proposed intramolecular chemically initiated electron exchange luminescence (CIEEL) mechanism which is enhanced by the electron-donating group of compound 2a. The second part involves the compounds 1a, and 5-halo substituted of 1,2-dioxetane tricyclic compounds (3a, 4a) to study the heavy atom effect on their chemiluminescent efficiency both in fluorescence and phosphorescence. While upon heating to temperatures between 313~353K in dichloromethane, the chemiluminescent phosphorescence (CP) of the compounds 3a, 4a can be detected along with the chemiluminescent fluorescence (CF). The activation enthalpies from Eyring plots show that the decomposition of the 1,2-dioxetane favors the pathway of the triplet chemiexcitation processes due to the internal heavy atom effect.
Four tricyclic 1,2-dioxetane derivatives, 1a-4a, were synthesized from their corresponding 1,4-dioxin acenaphthylene compounds, 1-4, by reaction with singlet-oxygen (1O2) in dichloromethane. The first part which involves the thermal decomposition of the compounds 1a-3a illustrates the substituent effect on the ability of the electron donating at 5-position of “acenaphtho” moiety. Evidence for formation of the dioxetanes ,1a-3a, is the chemiluminescence that corresponds to the emission from the electronically excited diesters 1b*-3b*, which are decomposed thermally from the dioxetanes 1a-3a, respectively. The highly strained 1,2-dioxetane ring decomposes from a twisted geometry by simultaneous cleavages of the O-O and C-C bonds producing the electronically excited diester that emits chemiluminescence (CL). It was observed that the CL from compound 2a is dramatically red-shifted relative to that of compounds 1a and 3a suggesting a higher degree of stabilization of the excited state by the electron donating methoxy group. Also, a study of the solvent effect on the fluorescence shows a significant red-shift in compound 2b, indicating a more polar excited state. The kinetics of the thermal decomposition of the 1,2-dioxetanes clearly demonstrate that the chemiluminescence characteristics of the compound 2a is quite different from that of compounds, 1a and 3a. These results are consistent with the proposed intramolecular chemically initiated electron exchange luminescence (CIEEL) mechanism which is enhanced by the electron-donating group of compound 2a. The second part involves the compounds 1a, and 5-halo substituted of 1,2-dioxetane tricyclic compounds (3a, 4a) to study the heavy atom effect on their chemiluminescent efficiency both in fluorescence and phosphorescence. While upon heating to temperatures between 313~353K in dichloromethane, the chemiluminescent phosphorescence (CP) of the compounds 3a, 4a can be detected along with the chemiluminescent fluorescence (CF). The activation enthalpies from Eyring plots show that the decomposition of the 1,2-dioxetane favors the pathway of the triplet chemiexcitation processes due to the internal heavy atom effect.
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化學發光, 三環1, 2-雙氧烷, 化激電子互換發光, 螢光, 磷光, 重原子效應, chemiluminescence, tricyclic-1, 2-dioxetane, chemically initiated electron exchange luminescence, fluorescence, phosphorescence, heavy atom effect