School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3217, Australia.
Anal Chem. 2010 May 15;82(10):4174-80. doi: 10.1021/ac100363s.
Spectroscopic and synthetic methods have been exploited to deduce the mechanism for acidic potassium permanganate chemiluminescence. We have employed electron paramagnetic resonance (EPR) spectroscopy with a continuous flow assembly to monitor the formation of radical intermediates in real time generated from substrate oxidation by manganese(VII). These transient species react with manganese(III) in solution to produce the previously characterized manganese(II)* emission source. Using UV-vis, EPR, attenuated total reflection (ATR)-FT-IR, and chemiluminescence spectroscopies, we have established that there are two distinct enhancement mechanisms that in combination afford a 50-fold increase in emission intensity when the reaction is conducted in the presence of phosphate oligomers. In addition to preventing disproportionation of the manganese(III) precursor, the phosphate oligomers form protective "cagelike" structures around the manganese(II)* emitter, thus preventing nonradiative relaxation pathways.
我们采用连续流动装置的电子顺磁共振（EPR）光谱法实时监测高锰酸根氧化底物时生成的自由基中间体。这些瞬态物种与溶液中的三价锰反应生成先前表征的锰(II)*发射源。通过紫外-可见、EPR、衰减全反射（ATR）-FT-IR 和化学发光光谱法，我们已经确定存在两种不同的增强机制，当反应在磷酸盐低聚物存在下进行时，这两种增强机制结合起来使发射强度增加了 50 倍。除了防止三价锰前体歧化外，磷酸盐低聚物还在锰(II)*发射器周围形成保护性的“笼状”结构，从而阻止非辐射弛豫途径。
