A unique benzimidazole-naphthalene hybrid molecule for independent detection of Zn2+ and N3- ions: Experimental and theoretical investigations

Single crystal X-ray structurally characterized benzimidazole-naphthalene hybrid (NABI) functions as a unique dual analyte sensor that can detect Zn2+ cation and Ni-3(-) anion independently. The NABI forms chelate with Zn2+ to inhibit internal charge transfer (ICT) and -CH=N- isomerisation resulting chelation enhanced fluorescence (CHEF). On the other hand, the sensing of N-3(-) is based on formation of supramolecular H-bonded rigid assembly. The association constant of NABI for Zn2+ and N-3(-) ions are 19 x 10(4) M-1 and 11 x 10(2) M-1, respectively. Corresponding limit of detections (LOD) are 6.85 x 10(-8) and 1.82 x 10(-7) M, respectively. NABI efficiently detects intracellular Zn2+ and N-3(-) ions with no cytotoxicity on J774A.1 cells under fluorescence microscope. DFT studies unlock underlying spectroscopic properties of free NABI and Zn2+/N-3(-) bound forms. (C) 2018 Elsevier B.V. All rights reserved.