Selective fluorometric detection of F− and Zn(ii) ions by a N, O coordinating sensor and naked eye detection of Cu(ii) ions in mixed-aqueous solutionElectronic supplementary information (ESI) available: X-ray crystallographic file in CIF format for HL; Fig. S1-S12 and Table S1. CCDC 1054382. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5ra05145b

• Main Authors: Hens, Amar, Rajak, Kajal Krishna
• Format: Journal Article
• Language: English
• Published: 18.05.2015
• ISSN: 2046-2069
• DOI: 10.1039/c5ra05145b

Through click chemistry, salicylaldehyde and fluorene groups have been explored to recognize anions through O-H A- hydrogen-bonding complexation followed by an ESIPT mechanism and cation sensing via CHEF and CHEQ mechanisms for Zn 2+ and Cu 2+ metal ions respectively. Herein, we demonstrate evidence of the interactions between the O-H bond and F − which were studied by fluorescence spectroscopic, UV-Vis spectroscopic, lifetime spectroscopic, 1 H NMR spectroscopic titrations and theoretical treatment. This sensor could simultaneously detect two biologically important metal ions (Cu 2+ and Zn 2+ ) through colorimetric methods in mixed aqueous solution. The 2 : 1 binding stoichiometry ratio of the ligand and metal in the complexes was established by UV-Vis, fluorescence, 1 H NMR and ESI-MS spectroscopy, and their corresponding association constants, K assoc observed at 8.13 × 10 4 and 5.12 × 10 6 M −1 corresponds to Zn 2+ and Cu 2+ metal ions in aqueous buffer-CH 3 OH (2 : 1, v/v) at pH 7.2. In addition, the electronic structures and photo physical properties of the ligand and complexes were calculated by DFT and time-dependent DFT (TDDFT) methods. A N, O coordinating sensor fluorogenically detects fluoride anions ( λ ex = 330 nm, λ em = 450 nm) with blue emission and Zn( ii ) ions with green emission ( λ ex = 405 nm, λ em = 515 nm) as well as colorimetrically detecting copper ions.