Cathodic electrochemiluminescence of acetonitrile, acetonitrile-1,10-phenanthroline and acetonitrile-ternary Eu(III) complexes at a gold electrode

• Published in: Luminescence (Chichester, England) England), 2006-03, Vol.21 (2), p.81-89
• Main Authors: Yu, Hong-Xiao, Cui, Hua, Guan, Jun-Bo
• Format: Article
• Language: English
• Subjects: 1,10‐phenanthroline; 10-phenanthroline; acetonitrile; Acetonitriles - chemistry; electrochemiluminescence; Electrochemistry - methods; Electrodes; Europium - chemistry; Free Radicals - chemistry; Gold - chemistry; gold electrode; Luminescence; Luminescent Measurements - methods; Molecular Structure; Organometallic Compounds - chemistry; Phenanthrolines - chemistry; Sensitivity and Specificity; ternary Eu(III) complexes; tetrabutylammonium peroxydisulphate
• ISSN: 1522-7235; 1522-7243; 1099-1271
• DOI: 10.1002/bio.888

Cathodic electrochemiluminescence (ECL) behaviours of the acetonitrile, acetonitrile–1,10‐phenanthroline (phen) and acetonitrile–ternary Eu(III) complex systems at a gold electrode were studied. One very weak cathodic ECL‐2 at −3.5 V was observed in 0.1 mol/L tetrabutylammonium tetrafluoroborate (TBABF4) acetonitrile solution. When 10 mmol/L tetrabutylammonium peroxydisulphate [(TBA)2S2O8] was added to 0.1 mol/L TBABF4 acetonitrile solution, another cathodic ECL‐1 at −2.7 V appeared and the potential for ECL‐2 was shifted from −3.5 to −3.1 V. Furthermore, ECL‐2 intensity was enhanced about 20‐fold. When 1 × 10−4 mol/L phen was added to 0.1 mol/L TBABF4 + 10 mmol/L (TBA)2S2O8 acetonitrile solution, the ECL intensities of ECL‐1 and ECL‐2 were enhanced about 20‐fold compared with those of 0.1 mol/L TBABF4 + 10 mmol/L (TBA)2S2O8 acetonitrile solution. The maximum emission peaks of ECL‐1 and ECL‐2 in the three systems mentioned above appeared at about 530 nm. The products obtained by electrolysing 0.1 mol/L TBABF4 acetonitrile solution at −3.5 V for 20 min were analysed by Fourier Transform Infrared (FTIR) spectra and gas chromatography–mass spectrometry (GC–MS) and the emitter of ECL‐1 and ECL‐2 was identified as excited state polyacetonitrile. When ternary Eu(III) complexes were presented in 0.1 mol/L TBABF4 + 10 mmol/L (TBA)2S2O8 acetonitrile solution, another maximum emission peak with a narrow band centred at about 610 nm appeared in ECL‐1 in addition to the maximum emission peaks at about 530 nm for ECL‐1 and ECL‐2. The emitter of ECL emission at 610 nm was identified as the excited states Eu(III)*. The mechanisms for cathodic ECL behaviours of the acetonitrile, acetonitrile–phen and acetonitrile–ternary Eu(III) complex systems at a gold electrode have been proposed. The extremely sharp emission bands for ternary Eu(III) complexes may have analytical potential. Copyright © 2006 John Wiley & Sons, Ltd.