A quinoline derived first Schiff base silatrane for selective Be(II) sensing by UV-visible spectroscopy and fluorescence quenching: experimental and theoretical approach.

Abstract

A new quinoline based first Schiff base silatrane (BRQS) has been synthesized and characterized by FTIR, NMR, thermal analysis and mass spectrometry. The metal-ion sensing performance of BRQS was examined by UV-Visible absorption and fluorescence spectroscopy. BRQS showed high selectivity for Be(II) among the tested metal ions and formed a 1:1 complex as confirmed by Job's plot analysis with the association constant of 6.25 × 105 M-1. The sensor exhibited excellent sensitivity with detection limits of 41 nM (UV-Visible) and 55.2 nM (fluorescence). Fluorescence quenching analysis gave a Stern-Volmer constant of 2.4 × 106 M-1, indicative of a strong interaction between BRQS and Be(II). The sensing capability was successfully validated in spiked water samples with 96% recovery. The density functional theory (DFT) calculations corroborated the experimental results by a remarkable decrease of the HOMO-LUMO energy gap from 3.95 to 1.40 eV after complexation. BRQS also showed promising antioxidant activity (IC50 = 5.3 μM) and good binding toward the 5H5Q protein (-9.27 kcal mol-1). The findings show BRQS as a highly selective and sensitive chemosensor for Be(II) with additional antioxidant potential.

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