1400663-75-3Relevant academic research and scientific papers
Reactivity-based detection of copper(II) ion in water: Oxidative cyclization of azoaromatics as fluorescence turn-on signaling mechanism
Jo, Junyong,Lee, Ho Yong,Liu, Wenjun,Olasz, Andras,Chen, Chun-Hsing,Lee, Dongwhan
, p. 16000 - 16007 (2012/10/30)
An oxidative cyclization reaction transforms nonemissive azoanilines into highly fluorescent benzotriazoles. We have found that introduction of multiple electron-donating amino groups onto a simple o-(phenylazo)aniline platform dramatically accelerates its conversion to the emissive polycyclic product. Notably, this chemistry can be effected by μM-level concentrations of copper(II) ion in water (pH = 6-8) at room temperature to elicit >80-fold enhancement in the green emission at λem = 530 nm. Comparative kinetic and electrochemical studies on a series of structural analogues have established that the accelerated reaction rates correlate directly with a systematic cathodic shift in the oxidation onset potential of the azo precursors. In addition, single-crystal X-ray crystallographic analysis on the most reactive derivative revealed the presence of a five-membered ring intramolecular hydrogen-bonding network. An enhanced contribution of the quinoid-type resonance in such conformation apparently facilitates the mechanistically required proton transfer step, which, in conjunction with electron transfer at lower oxidation potential, contributes to a rapid cyclization reaction triggered by copper(II) ion in water.
