Effects of Structural Changes in the Amino group on the Relaxation Processes of Elecronically Excited Aromatic Amines

氨基结构变化对电子激发芳香胺弛豫过程的影响

• 批准号: 11640496
• 负责人: TOBITA Seiji
• 金额: $ 1.92万
• 依托单位: Gunma University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640496/
• 关键词: aromatic amines; internal conversion; fluorescence; radiationless transitions; solvent effects; substituent effects; transient absorption; photoionization; アミノナフタレン; 無輻射過程

Effects of structural changes in the amino group on the relaxation processes of N,N-dimethyl-1- aminonaphthalenes and aniline derivatives were investigated by time-resolved fluorescence, transient absorption and time-resolved photothermal measurements. For N,N-dimethyl-1-aminonaphthalenes it was revealed that structural changes from trwisted to quasi-planar from in the excited state induce vibronic coupling between closely-lying S_1 and S_2 states, resulting in very fast internal conversion in nonpolar solvents. Such a fast nonradiative process was also found for aniline derivatives which have a twisted amino group in the ground state. This work showed that characteristic solvent effects on the relaxation processes of excited aromatic amines could be attributed to structural changes of the amino group in the excited state.The structural change of the amino group from a pyramidal to quasi-planar upon electronic excitation results in intramolecular charge transfer from the nitrogen atom into the ring. As a result photoionization threshold is lowered and one-photon ionization upon 266 or 308nm photon excitation was found to become possible for aniline derivatives in water.

通过时间分辨荧光、瞬态吸收和时间分辨光热测量研究了氨基结构变化对N,N-二甲基-1-氨基萘和苯胺衍生物弛豫过程的影响。对于 N,N-二甲基-1-氨基萘，研究表明，从激发态从扭曲到准平面的结构变化会引起紧密相连的 S_1 和 S_2 态之间的振动耦合，从而导致非极性溶剂中非常快速的内部转换。对于基态具有扭曲氨基的苯胺衍生物也发现了这种快速的非辐射过程。这项工作表明，特征溶剂对激发态芳香胺弛豫过程的影响可归因于激发态氨基的结构变化。在电子激发下，氨基从金字塔形到准平面形的结构变化导致分子内电荷从氮原子转移到环中。结果，光电离阈值降低，并且发现水中的苯胺衍生物可以在 266 或 308 nm 光子激发下发生单光子电离。

项目成果

M.Moriyama, M.Kosuge, S.Tobita, and H.Shizuka: "Excited-state Intramolecular Proton Transfer Followed by Cis-trans Isomerization of (1-Hydroxy-2-naphthyl)-s-triazine Derivatives"Chem.Phys. 253. 91-103 (2000)

M.Moriyama、M.Kosuge、S.Tobita 和 H.Shizuka：“激发态分子内质子转移随后进行（1-羟基-2-萘基）-s-三嗪衍生物的顺反异构化”Chem.Phys。

S.Tajima,S.Tobita,andH.Shizuka: "Electron Transfer Reastion from Triplet 1,4-Dimethoxybenzene to Hydronium Ion in Aqueous Solution"J.Phys.Chem.. 103. 6097-6105 (1999)

S.Tajima、S.Tobita 和 H.Shizuka：“水溶液中从三重态 1,4-二甲氧基苯到水合氢离子的电子转移反应”J.Phys.Chem.. 103. 6097-6105 (1999)

K.Suzuki,A.Demeter,W.kuhnle,E.tauer,A.Zachariasse,,S.Tobita,andH.Shizuka: "Internal Conversion In 4-Substituted(Dimethylamino)naphthalenes.Influence of the Electron Donor/Acceptor Substituent Charaster"Phys.Chem.Chem.Phys.. 2. 981-993 (2000)

K.Suzuki、A.Demeter、W.kuhnle、E.tauer、A.Zachariasse、S.Tobita 和 H.Shizuka：“4-取代（二甲氨基）萘的内部转换。电子供体/受体取代基特征的影响

S.Tobita,K.Ida,and S.Shiobara: "Water-induced Fluorescence Quenching of Aniline and Its Derivatives in Aqueous Solution"Res.Chem.Intermed.. (in press). (2001)

S.Tobita、K.Ida 和 S.Shiobara：“苯胺及其衍生物在水溶液中的水诱导荧光猝灭”Res.Chem.Intermed..（出版中）。

K.Suzuki, A.Demeter, W.Kuhnle, E.Tauer, K.A.Zachariasse, S.Tobita, and H.Shizuka: "Internal Conversion in 4-Substituted 1-Naphthylamines. Influence of the Electron Donor/Acceptor Substituent Character"Phys.Chem.Chem Phys.. 2. 981-991 (2000)

K.Suzuki、A.Demeter、W.Kuhnle、E.Tauer、K.A.Zachariasse、S.Tobita 和 H.Shizuka：“4-取代 1-萘胺的内部转化。电子供体/受体取代基特征的影响”Phys