Calix diquinone receptor

Beer PD, Timoshenko V, Maestri M et al (1999) Anion recognition and luminescent sensing by new ruthenium(II) and rhenium(I) bipyridyl calix[4]diquinone receptors. Chem Commun... 

Taking into account om calix[4]tube ligand design10, the novel bis-calix[4]diquinone receptors were prepared via the initial synthesis of various bis-calix[4]arene derivatives connected by alkylene chain units and subsequent oxidation of the remaining phenolic... 

The Ru(II)bipyridylcalix[4]diquinone receptor 43 selectively binds and senses acetate anions (from H NMR titrations in DMSO-d6 solution K= 9,990 M1) [37]. This receptor exhibited only weak luminescence because calix[4]diquinone is an electron acceptor, quenching the [Ru(bpy)3]2+ emission... 

The Ru°bipyridylcalix[4]diquinone receptor 83 selectively binds and senses acetate anions (from NMR titrations in DMSO-de solution K = 9990 M ) [54]. This receptor is only weakly luminescent because the Ru (bpy)3 MLCT emission is partially quenched by oxidative electron transfer to the electron-poor calix[4]diquinone. Addition of acetate to acetonitrile solutions of 83 resulted in a five-fold increase in liuninescence intensity (60% for chloride) concomitant with a slight blue shift of the emission maximum. Anion binding causes this increase in emission intensity by interrupting the electron transfer pathway from the Ru°(bpy)3 to the calix[4]diquinone, thus reducing its quenching effect. 

Complexes of rheniiun(l)tricarbonylchloride with pyridyl ligands are lu-minophores and hence in anion sensing have principally been used as reporter groups. For instance calix[4]diquinone receptor 90 selectively binds and senses acetate in DMSO solution [54] (from H NMR titrations K = 1790 in DMSO-de solution). The receptor exhibits relatively weak lumi-... 

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