American Chemical Society
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Developing Red-Emissive Ruthenium(II) Complex-Based Luminescent Probes for Cellular Imaging

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journal contribution
posted on 2012-04-18, 00:00 authored by Run Zhang, Zhiqiang Ye, Yuejiao Yin, Guilan Wang, Dayong Jin, Jingli Yuan, James A. Piper
Ruthenium­(II) complexes have rich photophysical attributes, which enable novel design of responsive luminescence probes to selectively quantify biochemical analytes. In this work, we developed a systematic series of Ru­(II)-bipyrindine complex derivatives, [Ru­(bpy)3‑n(DNP-bpy)n]­(PF6)2 (n = 1, 2, 3; bpy, 2,2′-bipyridine; DNP-bpy, 4-(4-(2,4-dinitrophenoxy)­phenyl)-2,2′-bipyridine), as luminescent probes for highly selective and sensitive detection of thiophenol in aqueous solutions. The specific reaction between the probes and thiophenol triggers the cleavage of the electron acceptor group, 2,4-dinitrophenyl, eliminating the photoinduced electron transfer (PET) process, so that the luminescence of on-state complexes, [Ru­(bpy)3‑n(HP-bpy)n]2+ (n = 1, 2, 3; HP-bpy, 4-(4-hydroxyphenyl)-2,2′-bipyridine), is turned on. We found that the complex [Ru­(bpy)­(DNP-bpy)2]2+ remarkably enhanced the on-to-off contrast ratio compared to the other two (37.8 compared to 21 and 18.7). This reveals a new strategy to obtain the best Ru­(II) complex luminescence probe via the most asymmetric structure. Moreover, we demonstrated the practical utility of the complex as a cell-membrane permeable probe for quantitative luminescence imaging of the dynamic intracellular process of thiophenol in living cells. The results suggest that the new probe could be a very useful tool for luminescence imaging analysis of the toxic thiophenol in intact cells.