Fluorescent detection of Al(III) and CN− in solid and aqueous phases and their recognition in biological samples

Abstract

A new simple Schiff base based chemoreceptor (R) has been designed, synthesized and characterized using 1H and 13C NMR, mass and single crystal XRD techniques. R acts as an efficient fluorescent probe for selective detection of Al(III) and cyanide ions in methanol: water (20:80, v/v) medium thorough different emissions. The mode of coordination of R with Al(III) has been recognized by 27Al and 1H NMR and FT-IR studies and the results suggest an octahedral complex formation between them. The detection of cyanide occurs via the deprotonation of phenolic –OH group followed by nucleophilic addition of cyanide to imine C-atom which has been confirmed from 1H and 13C NMR titration experiments. R reacts with Al(III) and cyanide in a 1:1 stoichiometric manner with detection limits of 1.8 and 0.76 μM, respectively. The receptor shows an excellent ability for the detection these ions in a wide pH range. Most interestingly, R could detect these ions also in solid phase via similar mechanisms which are delineated using solid state reflectance, fluorescence and FT-IR spectral techniques and TD-DFT calculations. The probe has also been successfully applied for the bio-imaging of Al(III) in living cells and detection of endogenous biological cyanide in food samples.