Study of the characteristics of three high-energy intermediates generated in peroxyoxalate chemiluminescence (PO-CL) reactions
作者:Ji Hoon Lee、James C. Rock、Seung Bum Park、Mark A. Schlautman、Elizabeth R. Carraway
DOI:10.1039/b109210c
日期:2002.3.25
Perylene emission intensity generated from peroxyoxalate chemiluminescence (PO-CL) reactions was studied as a function of time and order of reagent addition. Based on 1H-NMR analyses, kinetics of UV absorbance and emission intensity vs. time profiles, we conclude that PO-CL reactions in the presence of imidazole (ImH) can proceed by three distinct reaction pathways depending on how the reagents are mixed together. When bis(2,4,6-trichlorophenyl) oxalate (TCPO) is mixed simultaneously with H2O2, ImH and perylene, a slowly decaying emission curve is generated from the interaction between perylene and a high-energy intermediate (i.e., six- or eight-membered cyclic compound) formed by the ImH-catalyzed nucleophilic reaction (TCPO-CL reaction). Upon mixing TCPO simultaneously with ImH and perylene in the absence of H2O2, however, distinctly different CL curves of lower intensity are generated from the interaction
between perylene and a new, unknown high-energy intermediate formed from the reaction between the aryl oxalate and ImH. Finally, using 1H-NMR, we observed that 1,1′-oxalyldiimidazole (ODI) is also formed from the reaction between TCPO and ImH. When ODI reacts with excess H2O2 in the presence of perylene, a higher intensity and relatively fast decaying emission curve is generated (ODI-CL reaction) from the interaction between perylene and the high-energy intermediate produced, which we propose is imidazolylhydroxydioxetanone or 1,2-dioxetanedione.
研究了过氧草酸酯化学发光(PO-CL)反应中生成的苝的发光强度随时间和试剂添加顺序的变化。根据1H-NMR分析、UV吸收和发光强度随时间的动力学曲线,我们得出结论:在存在咪唑(ImH)的情况下,PO-CL反应可以通过三种不同的反应途径进行,这取决于试剂是如何混合在一起的。当双(2,4,6-三氯苯基)草酸酯(TCPO)与H2O2、ImH和苝同时混合时,会产生一条缓慢衰减的发光曲线,这是由于苝与ImH催化的亲核反应(TCPO-CL反应)形成的高能中间体(即六元或八元环状化合物)相互作用的结果。然而,在没有H2O2的情况下,将TCPO与ImH和苝同时混合时,会产生一个强度较低且截然不同的化学发光曲线,这是由于苝与由芳基草酸酯和ImH反应形成的新型未知高能中间体相互作用的结果。最后,利用1H-NMR,我们观察到1,1'-草酰二咪唑(ODI)也是从TCPO和ImH反应中形成的。当ODI在苝存在下与过量的H2O2反应时,产生一个强度较高且相对快速衰减的发光曲线(ODI-CL反应),我们推测这是由于苝与形成的高能中间体(可能是咪唑基羟基二氧杂环丁酮或1,2-二氧杂环丁二酮)相互作用的结果。