Chemical Research in Chinese Universities ›› 2022, Vol. 38 ›› Issue (3): 816-822.doi: 10.1007/s40242-022-2036-7

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Effect of Ionic Strength on the Electrochemiluminescence Generation by Tris(2,2'-bipyridyl)ruthenium(II)/Tri-n-propylamine

HU Shifan, WANG Yafeng and SU Bin   

  1. Institute of Analytical Chemistry, Department of Chemistry, Key Laboratory of Excited-State Materials of Zhejiang Province, Zhejiang University, Hangzhou 310058, P. R. China
  • Received:2022-01-27 Revised:2022-02-23 Online:2022-06-01 Published:2022-02-28
  • Contact: WANG Yafeng, SU Bin E-mail:0621115@zju.edu.cn;subin@zju.edu.cn
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (Nos.22125405, 22074131 and 21874117) and the China Postdoctoral Science Foundation(No.2021M702804).

Abstract: Electrochemiluminescence(ECL) is a powerful transduction technique used in biosensing and in vitro diagnosis, while the mechanism of ECL generation is complicated and affected by various factors. Herein the effect of ionic strength on ECL generation by the classical tris(2,2'-bipyridyl)ruthenium(II)[Ru(bpy)32+]/tri-n-propylamine(TPrA) system was investigated. It is clear that the ECL intensity decreases significantly with the increase of ionic strength, most likely arising from the reduced deprotonation rate of TPrA+·. We further combined microtube electrode(MTE) with ECL microscopy to unravel the evolution of ECL layer with the variation of ionic strength. At a low concentration of Ru(bpy)32+, the thickness of ECL layer(TEL) nearly kept unchanged with the ionic strength, indicating the surface-confined ECL generation is dominated by the oxidative-reduction route. While at a high concentration of Ru(bpy)32+, ECL generation is dominated by the catalytic route and TEL increases remarkably with the increase of ionic strength, because of the extended diffusion length of Ru(bpy)33+ at a reduced concentration of TPrA·.

Key words: Electrochemiluminescence(ECL), ECL layer thickness, ECL microscopy, Ionic strength, Reaction mechanism