Development of moderately fluorescence active salen type chemosensor for judicious recognition and quantification of Zn(II), Al(III) and SO4=: Demonstration of molecular logic gate formation and live cell images studies

Abstract

A Salen type Schiff base H3L, generated by the one step condensation of 1, 3 diamino 2-propanol and 3- ethoxy salicylaldehyde, for selective and easy detection of the two different cations Zn(II), Al(III) and one specific anion SO4= among several competitive cations and anions in 1:9 methanol water HEPES buffer medium. This probe with moderate luminescence property exhibits elevated fluorescence enhancement with different shifting of spectral position during detection of Al(III) / Zn(II) and fluorescence diminution at the time of SO4= detection. One another interesting noticeable fact is that, with the help of F− ion Zn(II) can be detected in presence of Al(III) whereas by using CN− ion Al(III) can be detected in presence of Zn(II). The moderately higher binding constant values, measured from the probe-analytes electronic titration and the results obtained from the fluorescence lifetime study, convince us regarding the formation of Zinc/Aluminum/SO4= -probe complexes during sensing by the chemosensor H3L. The 1:1 binding mechanisms between H3L and Al(III)/Zn(II)/SO4= ions are propped up by HR-MS analysis and NMR/FTIR titration. The mononuclear structure of Zn(II)-H3L / Al(III)-H3L and SO4=H3L complexes are optimized by implementing Density Functional Theory (DFT) study. The sensing phenomena of two metal ions are further utilized to form a molecular logic gate formulation. Interestingly, this chemosensor can effectively detect and quantify all the aforementioned ions in tap water. Finally, the bio sensing ability of the chemosensor has been inspected by performing the fluorescence live cell imaging study, showing the intercellular Zn(II) sensing efficacy.