Dual sensing and synchronous fluorescence spectroscopic monitoring of Cr3+and Al3+ using a luminescent Schiff base: Extraction and DFT studies

A well designed, new pyrene based small molecule (L) was synthesized from 1:1 condensation reaction of 1-aminopyrene and 6-(1,3-benzodioxal-5-yl)-2-pyridine carboxaldehyde which was characterized by absorption, emission spectrometry, FTIR, NMR and mass studies. Interestingly the UV-vis and fluorescence spectroscopic studies revealed that the ligand (L) works as a dual turn-on luminescent chemosensor for chromium(III) (Cr3+) and aluminium(III) (Al3+) in aqueous environment which were further supported by DFT and TDDFT studies. L shows a significant colour change from pale yellow to reddish yellow with a detection limit of similar to 10(-9) M in the presence of Cr3+ and Al3+ whereas there were no noteworthy changes in the presence of other monovalent and divalent metal ions. The molecular signaling in the presence of Cr3+, Al3+, Fe3+ and EDTA was compared with advanced level combinational INHIBIT gate based on 4 input logic gates. Herein, first derivative constant wavelength synchronous fluorescence spectroscopy (1st DCWSFS) was applied for the determination of Cr3+, Al3+ ion concentrations in a mixture via increment of spectral resolution of the respective overlapping peaks. 1st DCWSFS is reported to be used in pharmaceuticals but very few works have been done for determination of metal ion concentration in environmental sample without prior separation. The individual Cr3+ and Al3+ ion concentrations in a mixture were determined through liquid-liquid extraction process and the efficiencies were compared with 1st derivative SFS method. It was observed that 1st derivative SFS process is more efficient than conventional liquid-liquid extraction process. Therefore, 1st DCWSFS method using sensor L might be useful as a diagnostic tool for detection of individual metal ion concentrations (Cr3+ and Al3+) from a mixture which will be cost-effective, time saving and more precise. (c) 2019 Elsevier B.V. All rights reserved.