A combined theoretical and experimental study of ratiometric fluorescent Schiff base chemosensor for detection of Fe3+ ion and its anticancer activity

Abstract

Schiff-base fluorescent chemosensor (E)-N-(4-(dimethylamino)benzylidene)quinolone-3-amine (DBQA) was synthesized and characterized by FT-IR,¹H NMR,¹³C NMR, ESI-MS spectrometry and Single X-ray crystallographic studies. The synthesized chemosensor (DBQA) was used for the detection of Fe³⁺ successfully. UV-visible and fluorescence spectra of (DBQA) exhibits a ratiometric behaviour along with a bathochromic shift upon the successive addition of Fe³⁺. The fluorescence spectra of chemosensor (DBQA) were recorded followed by addition of concentrations of different metal ions and NH₃. The chemosensor (DBQA) showed a favourable linear relationship between the fluorescence intensity and concentration of Fe³⁺ ion. DBQA exhibits a ratiometric response and illustrates high sensitivity (with a detection limit of 0.4 ​μM) and good selectivity for the Fe³⁺ ion over other transition metal ions. DBQA shows 0.6 ​μM detection limit for NH₃ along with ratiometric behaviour also. The association constant (K_a) of chemosensor (DBQA) was found to be 1.455×10² ​M^-1/2 for Fe³⁺. The mechanism of sensing of the present ratiometric fluorescent chemosensor (DBQA) was explained by ICT (Intra-molecular charge transfer) using DFT calculations. The interaction model of chemosensor (DBQA) with Fe³⁺ was determined to be 2:1 stoichiometry using Job's plot analysis and ESI-MS spectra which further confirms DFT studies. Moreover, tested DBQA ​+ ​Fe³⁺ was showed that remarkable anticancer activity against the HCT116 colon cancer cells by MTT assay. Novelty and importance of DBQA as it can be investigate, test or analyse of detect Fe³⁺ rapidly as compared to other tested ions. Lastly, DBQA can be investigate, test or analyse of Fe³⁺ in environmental and biological samples.