1 陳順基 明志科技大學化工系 The Exciplex Formation of Charge-Transfer Induced 4- Phenylbenzophenone with Triethylamine and the Application in Photochemistry 4- 苯基二苯甲酮與三乙胺電荷 - 轉移誘導 激態複合體的形成及其光化學的應用 中華民國一百年十二月二十四日

Jablonski Diagram 2 Photophysics Photochemistry

Identification of (n,  *) & ( ,  *) 3 單態的（ n,  * ）及（ ,  * ）性質： 參態的（ n,  * ）及（ ,  * ）性質： 3 (n,  *) 3 ( ,  *) 磷光生命期 < ～ sec > 1 sec 磷光振動結構恆定可變  E ST < 36 kJ/mol （酮類） > 60 kJ/mol S 0  T 1 躍遷強度 f ~  f ~ （烴類） 重原子效應對 S 0  T 1 躍遷強度影響 影響小強度增大 ESR 信號無有 1 (n,  *) 1 ( ,  *) 吸收強度弱強 溶劑效應藍移紅移 躍遷的極性重直於分子面平行於分子面 能量 通常為最低能量躍遷 （共軛系統中有例外）

4 Molecular Complex Electron donor-acceptor complex (EDA complex) Mulliken CT 吸收理論 Ψ(S 0 ) = aΨ (DA) + bΨ (D+A-) Ψ(S 1 ) = aΨ (D+A-)  bΨ (DA)  E CT = I D  E A  (  H 1   H 0 ) S 1 S 0  E CT I D E A D + + A - D + A  H 1  H 0 D A 間距離 E

5 激態雙體 (Excimer, Excited dimer) (Forster et al Z. Phys. Chem. 1954)

6 激態複合體 (exciplex, excited complex) (Leonhardt et al Ber. Bunsenges. Phys. Chem. 1963)

7 Photophysics of BP & PBP BP 及 PBP 吸收及溶劑效應 化合物名稱 四氯化碳 (nm) 苯 苯 (nm)  (M -1 cm -1 ) EPA (nm) 氰甲烷 (nm) BP PBP~ 350 ~ ~ 347

8 Vibrational structure Vibrational structure provides clues as to which transitions are most possible Emission of biphenyl

9 Lifetimes & Quantum yields BP 及 PBP 在 EPA 中的低溫磷光生命期 Monitored at pp R2R2 BP （ 413 nm ） 5.26 ms BP （ 444 nm ） 5.28 ms BP （ 476 nm ） 5.29 ms PBP （ 469 nm ） ms PBP （ 499 nm ） ms BP 及 PBP 螢、磷光相對量子產率 化合物名稱 298 K77 K ff pp ff pp BP~  ~ PBP~  ~ 00.46

10 State energy diagram Phenyl-substitutent can stabilize the ( ,  *) energy levels.

11 Phosphorescence Quenching of BP TEA 的濃度 （ M ） 磷光強度比值 （  o /  ） BP 的磷光生命期 a （  s ） x x x x x a. Monitored at 450nm

12 Stern-Volmer Analysis Quenching rate constant k q a （ M -1 s -1 ） 1.5×10 9 k q b （ M -1 s -1 ） 2.2×10 9 k q c （ M -1 s -1 ） 2×10 9 a ： steady-state b ： transient lifetime c ： Fouassier J. Chim Phys. 1983

13 Excitation spectra Phosphorescence Quenching of PBP

14 Solvent Effect of PBP-TEA Exciplex

15 Stern-Volmer Plot TEA 的濃度 （ M ） PBP 的生命期 a （  s ） x x x x x x x a. Monitored at 480nm k q = 4.52  10 7 M -1 s -1

16 Thermodynamics of Exciplex T （℃） k q × 10 – 7 （ M -1 s -1 ） Arrhenius plot k q = Aexp(-E ‡ a /RT) E ‡ a =1.8 kcal/mol

17 Stevens-Ban plot Thermodynamics of Exciplex ln[  (CT)/  (LE)] = A   H/RT

18 Potential Energy Curve  E rep (LE) = E LE  hv LE  E rep (CT) = E LE  hv CT   H

19 各種胺類在室溫的 Stern-Volmer plot

20 AMINE IP （ eV ） k q × 10 – 7 （ M -1 s -1 ） R PA8.78No quenching- DEA DPA TEA TPA TiPA 不同胺類的淬熄效應

21 不同溫度各種胺類的淬熄速率常數 kq×10 –7 (M -1 s -1 ) 溫度 （℃） DEADPATEATPATiPA Temperature-dependent quenching

22 各種胺類的 Arrhenius plot Temperature-dependent quenching 各種胺類淬熄參態 PBP 的活化能與前指數因子 DEADPATEATPATiPA IP(eV) Ea(kcal/mol) log A

23 PBP-TiPA 系統在不同溫度的磷光光譜 PBP-TiPA 系統的 Stevens-Ban 圖

24 Photoreduction of BP

25 Photoreduction of PBP

26 PBP-TEA 隨照光時間產物消長的 HPLC 圖 （ t R = 7 為 PBP ， t R =11.5 為 4-phenylbenzopinacol ） Photoreduction of PBP

27 電荷 - 轉移誘導的光還原反應機構 Photoreduction of PBP

28 BP- 系列光引發聚合反應 TMPTA 硬化前之 FTIR 圖 TMPTA-PBP-TEA 硬化後之 FTIR 圖

Conclusion 29 1.The photophysical analysis confirmed that the low-lying excited singlet and triplet states of PBP is 1 (n,  *), 3 ( ,  *) respectively. Thus, an intramolecular energy transfer has occurred from the n   * of carbonyl to the  *   of biphenyl. 2.Direct evidence for triplet exciplex formation of excited PBP triplet with amines was provided by the observation of emission at longer wavelengths than that of the phosphorescence of PBP. 3.The quenching rate constants were dependent on the ionization potentials of amines. The trend reflects on the calculated activation energies (E a ) for exciplex formation of 3 PBP and amines.

30 4.The stabilization enthalpy (  H) of exciplex increases with increasing steric effect of amines from TEA to TiPA, " Entropy Control" is expected to widely contribute to the exciplex formation for PBP-TiPA system under high- temperature limit region. 5.The bimolecular reactivity of photoreduction is very fast for lowest 3 (n,  *), but ( ,  *) triplet is almost unreactive without amine electron donor. A new mechanism of hydrogen atom abstraction has been proposed by rapid charge-transfer to form an exciplex with TEA following proton transfer. 6.The PBP-TEA is an efficient photoinitiator and shows the same charge-transfer induced radical’s formations that are able to initiate the polymerization of acrylic type monomers. Conclusion

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