“Off‐on‐off” Fluorescence pH Switch of Three Trinuclear RuII Complexes Containing Imidazole Rings |
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| Authors: | Dr Feixiang Cheng Jishu Chen Fan Wang Ning Tang Longhai Chen |
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| Institution: | 1. College of Chemistry and Chemical Engineering, Qujing Normal University, Qujing 655011, P. R. China;2. College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, P. R. China |
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| Abstract: | Three tripodal ligands H3L1–3 containing imidazole rings were synthesized by the reaction of 1,10‐phenanthroline‐5,6‐dione with 1,3,5‐tris(3‐formylphenoxy)methyl]benzene, 1,3,5‐tris(3‐formylphenoxy)methyl]‐2,4,6‐trimethylbenzene, and 2,2′,2"‐tris(3‐formylphenoxy)ethyl]amine, respectively. Trinuclear RuII polypyridyl complexes (bpy)6Ru3H3L1–3](PF6)6 were prepared by the condensation of Ru(bpy)2Cl2 · 2H2O with ligands H3L1–3. The pH effects on the UV/Vis absorption and fluorescence spectra of the three complexes were studied, and ground‐ and excited‐state ionization constants of the three complexes were derived. The three complexes act as “off‐on‐off” fluorescence pH switch through protonation and deprotonation of imidazole ring with a maximum on‐off ratio of 5 in buffer solution at room temperature. |
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| Keywords: | Ruthenium pH Switch UV/Vis spectroscopy Fluorescence Imidazole |
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