Selective interactions of 5-(hydroxyimino)quinolin-8-one with tetrabutylammonium fluoride and zinc(ii) ions

Abstract

5-(Hydroxyimino)quinolin-8-one (HL) selectively interacts with tetrabutylammonium fluoride to form a supramolecular adduct. Formation of the supramolecular adduct in solution causes a drastic color change or causes quenching of the fluorescence emission of HL enabling its distinction from other tetrabutylammonium halides. Among different metal ions, addition of zinc ions to a solution of HL causes a selective color change or very distinguishable fluorescence emission intensity enhancement from other cations. The selective colouration of HL due to an increase in absorption at ∼640 nm in acidic condition in a similar way upon addition of zinc or fluoride ions is attributed to their ability to deprotonate HL. Di-aqua-bis(5-nitroso-8-oxyquinolinato)zinc(II) is structurally characterized. It shows strong visible absorption at 718 nm, which differs from the absorption of species formed in acidic conditions by zinc causing visual color change.