Publication Date:
2011-03-25
Description:
Three tripodal ligands H 3 L 1–3 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 Ru II polypyridyl complexes [(bpy) 6 Ru 3 H 3 L 1–3 ](PF 6 ) 6 were prepared by the condensation of Ru(bpy) 2 Cl 2 · 2H 2 O with ligands H 3 L 1–3 . 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.
Print ISSN:
0044-2313
Electronic ISSN:
1521-3749
Topics:
Chemistry and Pharmacology
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