A novel water-soluble highly selective switch-on ionic liquid-based fluorescent chemi-sensor for Ca(II)

A novel chemi-sensor involve new bis-ionic Schiff base sensor (BISBS), N,N'-bis-[5-(2,4-lutidiniumchloride)methylene)-3-methoxysalicylidene]-R,R-1,2-cyclohexanediimine, has been synthesized and characterized. BISBS chemi-sensor was designed based on internal charge transfer (ICT) fluorescence mechanism. This new water soluble chemi-sensor provides great selectivity fluorescence detection for Ca(II) ions in an important physiological pH range. Moreover, the interaction of Ca(II) with the deprotonated BISBS to produce a metal-ligand complex with a ratio of (1: 1) accompanying with an enhancement in the intensity of emission band located at 502 nm. Fluorescence switching-on during the chemical interaction between BISBS and Ca(II) ions is very easily noticed with naked eye, but other metal cations such as alkali, alkaline earth and transition metal don't give any fluorescence changes. The novel developed BISBS sensor successively offers low limit of detection (LOD) 1.5 nM and fast tracing of Ca(II) in the physiological pH 7.6. Thus BISBS may provide a novel auspicious methodology for detection calcium cations in the environmental and biological samples. (C) 2017 Elsevier B.V. All rights reserved.