Title

Electrogenerated Chemoluminescence (ECL) Quenching of the Ru(bpy)32+/TPrA System by the Explosive TNT

Document Type

Article

Publication Date

10-20-2015

Department

Chemistry and Biochemistry

Abstract

We report the quenching behavior of 2,4,6-trinitrotoluene (TNT) on the electrogenerated chemiluminescence (ECL) of the Ru(bpy)32+/TPrA [bpy = tris(2,2′-bipyridine), TPrA = tri-n-propylamine] system at a Pt electrode in acetonitrile containing tetra-n-butylammonium perchlorate supporting electrolyte. Effective ECL quenching of the system upon the addition of TNT was observed, with a Stern-Volmer constant of 2 × 104 M−1. The quenching constant calculated from the Stern-Volmer plot was found to be 2.1 × 1010 M−1 s−1 which suggests the efficient quenching of ECL by TNT. The competitive processes of consuming TPrA free radicals and Ru(bpy)32+ species (produced as a result of reduction of Ru(bpy)32+ by TPrA) by TNT largely contributed to this quenching, in which the consumption of Ru(bpy)32+ by TNT was more favorable than that of TPrA free radicals. TNT was also found to quench the fluorescence of Ru(bpy)32+, with a Stern-Volmer and a quenching constant of 5.2 × 103 M−1 and 5.5 × 109 M−1 s−1, respectively. This collisional (dynamic) based fluorescence quenching process contributed approximately one quarter of the overall ECL quenching efficiency. The present ECL quenching scheme could be used to detect TNT at submicromolar levels.

Publication Title

Electrochimica Acta

Volume

180

First Page

196

Last Page

201

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