Wolf Jannic, Huhn Thomas, Steiner Ulrich E
Fachbereich Chemie, Universität Konstanz, D-78457 Konstanz, Germany.
Phys Chem Chem Phys. 2015 Feb 28;17(8):6066-75. doi: 10.1039/c4cp05258g.
A recently reported protolytic gating effect on the ring closing reaction of an oligo(phenylene ethynylene) (OPE) embedded difurylperfluorocyclopentene (S) with a dimethylaminophenyl chain link in each of the side arms, was quantitatively analyzed in detail. The reaction system (So, SoH(+), SoH2(2+), Sc, ScH(+), ScH2(2+)) comprising three protolytic forms in both open and closed configuration, is characterized by four protolytic equilibrium constants and six photochemical quantum yields of ring closing and ring opening. The absorption spectra, conductivity, and effective photochemical quantum yields were measured in acetonitrile as functions of solvent acidity varied by addition of trifluoroacetic acid and triethylamine and characterized by an effective pHnon-aq. Based on the derivation of a rigorous method for assessing the individual quantum yields of ring closure and ring opening of the six species, it was shown that it is specifically the second protonation step that is responsible for a more than 10-fold increase in the quantum yield of ring closure.
最近报道了一种质子化门控效应，该效应作用于一种低聚（亚苯基乙炔）（OPE）嵌入的二呋喃基全氟环戊烯（S）的闭环反应，其每个侧臂都带有二甲基氨基苯基链节，对此进行了详细的定量分析。该反应体系（So、SoH(+)、SoH2(2+)、Sc、ScH(+)、ScH2(2+)）在开放和闭合构型中均包含三种质子化形式，其特征在于四个质子化平衡常数以及六个闭环和开环的光化学量子产率。在乙腈中测量了吸收光谱、电导率和有效光化学量子产率，它们是通过添加三氟乙酸和三乙胺来改变溶剂酸度的函数，并通过有效非水pH值进行表征。基于推导的一种评估六种物质闭环和开环各自量子产率的严格方法，结果表明，具体而言正是第二个质子化步骤导致闭环量子产率增加了10倍以上。
