Pyrene derived imine functionalized moiety for highly selective colorimetric detection of Cu2+ ion real time sample with supportive DFT studies

Abstract

Schiff base probe 4-hydroxy-N-(pyrene -1-yl-methylene) benzo hydrazide (PyrBH) has been synthesized and rationally designed as a rapid and highly selective colorimetric sensor for Cu2+ ions in the semi-aqueous medium. Structural characterization of PyrBH was confirmed by NMR, FT-IR, and HRMS spectral techniques. The cation binding affinity with the PyrBH probe was confirmed colorimetric study using the UV-Visible spectral method. The probe PyrBH exhibits a colorimetric response from colourless to yellow solutions containing Cu2+ ions. UV-Visible studies confirmed the formation of a 1:1 stoichiometry complex with a calculated binding constant Ka value (3.464 × 10-5 M) of suggests stable complex formation between the Cu2+ ions and the sensing PyrBH probe. The limit of detection (LOD) was found to be 2.19 × 10-7 M. The fabrication of test paper strips with the probe was done to detect the presence of Cu2+ ions in the real sample. The DFT & TD-DFT computational analysis was used to determine the highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels, which it associates with satisfactory correlation.