Functional Dimming of Pincer‐Shaped Bibenzimidazole‐Ruthenium(II) Complexes with Improved Anion‐Sensitive Luminescence. Issue 10 (9th March 2016)

• Record Type: Journal Article
• Authors: Sorsche, Dieter; Rommel, Sebastian A.; Rau, Sven
• Is Part Of: European journal of inorganic chemistry. Issue 10(2016)
• Page Start: 1503
• Page End: 1513
• Publication Date: 2016-03-09
• Subjects: Ruthenium -- N ligands -- Anions -- Sensors -- Luminescence; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201501472
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: Three 2, 2′‐bibenzimidazole‐bis(4, 4′‐di‐ tert ‐butyl‐2, 2′‐bipyridine)ruthenium(II) complexes are presented and characterized with respect to their photophysical and structural properties. 4, 4′, 5, 5′‐Tetramethyl‐2, 2′‐bibenzimidazole (L0 ), 4, 4′‐di( p ‐anisyl)‐2, 2′‐bibenzimidazole (L1 ), and the ruthenium complexesK0 andK1 have been reported previously. The new complexK2 contains the structurally confined ligand 4, 4′‐di( o, o ′‐dimethyl‐ p ‐anisyl)‐2, 2′‐bibenzimidazole. Owing to substitution at the 4, 4′‐positions of the bibenzimidazole ligands, complexesK1 andK2 have pincer‐like geometries, as shown by 1 H NMR spectroscopy and XRD studies. The emission intensities of these complexes are dimmed compared with that ofK0, whereas titration experiments with tetrabutylammonium (TBA) salts of fluoride, chloride, bromide, and iodide show strongly enhanced sensitivity to hydrogen bonding with chloride and bromide ions, which increases the emission intensity to ca. 300 % of the original value, and they eventually outperformK0 . With regard to the luminescence sensitivities, K1 andK2 set a new benchmark among 2, 2′‐biimidazole ruthenium(II) colorimetric halide sensors. Abstract : Ruthenium chromophores of pincer‐shaped 2, 2′‐bibenzimidazole ligands exhibit improved sensing properties towards halide ions through the strong amplification of their initially weak luminescence.