NIR sensing of Zn(ii) and subsequent dihydrogen phosphate detection by a benzothiazole functionalized ninhydrin based receptor†
Abstract
A benzothiazole functionalized ninhydrin based chemosensor (L1), exhibits selective naked eye detection of biologically important zinc ions (from light yellow to orange) accompanied by a ‘turn-on’ fluorescence emission response in the near infra-red (NIR) region. Most importantly, Zn2+ ion induced ‘turn-on’ fluorescence emission is also preserved in the presence of Cd2+ and most of the other competing metal ions which clearly suggests the high sensitivity of the chemosensor towards Zn2+. The Job's plot suggests 1 : 1 binding of the L1 with the Zn2+ ion with a detection limit of 6 nM. Detailed 1H NMR titrations were also conducted to understand the binding behaviour of L1 towards the Zn2+ ion. The ‘L1–Zn2+ ensemble’ further shows a ratiometric response to H2PO4− among other competitive anions and nucleotides in the same experimental conditions.