A potential sensor for assessing thorium (IV) based on Albuterol sulfate fluorescence enhancement: A density functional theory (DFT) study

Abstract

• Introducing a new fluorescent sensor for assessing Th(IV) in environmental samples. • Fluorescence mechanism was discussed. • HOMO and LUMO energy levels has been calculated by DFT. This study introduces a potential fluorescence sensor for assessing thorium (Th(IV)) in aquatic environments. In the presence of Th(IV), Albuterol Sulfate ( ABS ) 4-[2-( tert -butylamino)-1-hydroxyethyl]-2-(hydroxymethyl)phenol; sulfuric acid exhibits significant fluorescence enhancement at 600 nm. The current ABS ligand sensor shows wide linear range from 6.0 × 10 −8 – 2.5 × 10 −7 mol/L and pH range of 4–6. Interestingly, when all evaluated interference ions coexisted, the change in fluorescence emission intensity of ABS -Th complex was roughly 2.3 %. The binding mode is studied and indicating a 2:1 complex formation between ABS ligand and Th (IV). Density functional theory (DFT) has been utilized to examine the interaction characteristics between the present ABS ligand sensor and Th(IV) and to compute the geometric configuration of the ABS and ABS -Th through the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels. The interaction properties exhibit considerable effect on the HOMO and LUMO properties of the complexes, as well as a fluorescence enhancement that could be attributable to the heavy atom effect of Th (IV). The ABS sensor shows remarkable features and provides good performance compared to some of the optical sensors, making it a potential new fluorescence sensor for Th(IV) assessment.