瞬态吸收光谱研究2-甲基-1-硝基萘光化学反应
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- 英文论文题名：Transient Absorption Spectroscopic Study of Photoreaction of 2-Methyl-1-Nitronaphthalene
- 论文作者：关怀昱 ; 薛佳丹 ; 郑旭明
- 英文论文作者：Huaiyu Guan ; Jiadan Xue ; Xuming Zheng ; Department of Chemistry ; Zhejiang Sci-Tech University
- 年：2016
- 作者机构：浙江理工大学化学系;
- 论文关键词：硝基多环芳烃 ; 纳秒瞬态吸收光谱 ; 激发态分子内氢转移
- 会议召开时间：2016-07-01
- 会议录名称：中国化学会第30届学术年会摘要集-第四十四分会：化学动力学
- 语种：中文
- 分类号：O644.1
- 学会代码：ZGHY
- 会议名称：中国化学会第30届学术年会-第四十四分会 ; 化学动力学
- 会议地点：中国辽宁大连
- 主办单位：中国化学会
- 学会名称：中国化学会
- 页数：1
- 文件大小：326k
- 原文格式：D
- 会议级别：全国
摘要
硝基多环芳烃(NPAHs)广泛存在于受污染的大气中,多数NPAHs及其光解产物具有致癌和致突变作用。邻位基团含氢的NPAHs具有激发态分子内氢转移性质,利用这一性质这类分子作为光致离去的保护基团(Photoremovable protecting groups,PPGs)广泛应用于生物分子捕获、DNA及其他生物分子合成等。S_1(FC)态NPAHs有两条衰减路径,其一弛豫到S_(diss)(CT),分解为芳氧自由基(Aryl-O);另一条为系间窜越到三重态。本文利用纳秒瞬态吸收光谱研究了2-甲基-1-硝基萘(2Me1NN)激发态性质,在400 nm处拟合了三个衰减寿命,结合实验与DFT/TD-DFT计算分别指认为最低三重态、分子内氢转移产物以及芳氧自由基。分子内氢转移产物有一部分来自最低三重态,CASSCF/CASPT2方法计算的过渡态能垒为9.43 kcal/mol。
Nitro-polycyclic aromatic hydrocarbons(NPAHs) have been identified in ambient pollutional atmospheres, as carcinogen and mutagen. NPAHs with hydrogen(s) existing in the ortho-group of nitro chromophore easily undergo excited state intramolecular hydrogen transfer reaction. The excited singlet state of NPAHs in the Franck-Condon region has two deactivation pathways. Internal conversion or relaxing to an intramolecular charge-transfer state, and then dissociate into aryloxy radical(Aryl-O). The other pathway is intersystem crossing to the triplet state. In this report, nanosecond transient absorption spectroscopy was employed to investigate photoreactions of 2-Methyl-1-Nitronaphthalene(2Me1NN) in organic and aqueous solutions. The decay kinetics at 400 nm can be fit with a tri-exponential function, and assigned to the lowest triplet state, the intermediate of intramolecular hydrogen transfer and aryloxy radical, respectively, with the help of DFT/TD-DFT calculations. The energy barrier of intramolecular hydrogen transfer from the lowest triplet state is predicted to be 9.43 kcal/mol by CASSCF/CASPT2 level calculations.
Nitro-polycyclic aromatic hydrocarbons(NPAHs) have been identified in ambient pollutional atmospheres, as carcinogen and mutagen. NPAHs with hydrogen(s) existing in the ortho-group of nitro chromophore easily undergo excited state intramolecular hydrogen transfer reaction. The excited singlet state of NPAHs in the Franck-Condon region has two deactivation pathways. Internal conversion or relaxing to an intramolecular charge-transfer state, and then dissociate into aryloxy radical(Aryl-O). The other pathway is intersystem crossing to the triplet state. In this report, nanosecond transient absorption spectroscopy was employed to investigate photoreactions of 2-Methyl-1-Nitronaphthalene(2Me1NN) in organic and aqueous solutions. The decay kinetics at 400 nm can be fit with a tri-exponential function, and assigned to the lowest triplet state, the intermediate of intramolecular hydrogen transfer and aryloxy radical, respectively, with the help of DFT/TD-DFT calculations. The energy barrier of intramolecular hydrogen transfer from the lowest triplet state is predicted to be 9.43 kcal/mol by CASSCF/CASPT2 level calculations.
引文
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[2]Vogt,R.A.;Reichardt,C.;Crespo-Hernandez,C.E.J.Phys.Chem.A.2013,117(30):6580.
[3]Klán,P.;S?olomek,T.;Bochet,C.G.;et al.Chem.rev.2012,113(1):119.
[2]Vogt,R.A.;Reichardt,C.;Crespo-Hernandez,C.E.J.Phys.Chem.A.2013,117(30):6580.
[3]Klán,P.;S?olomek,T.;Bochet,C.G.;et al.Chem.rev.2012,113(1):119.