Selective detection of Fe³⁺ via fluorescent in real sample using aminoanthraquinone resorcin[4]arene-based receptors...

Resorcin[4]arene based fluorescent sensors RES-AAQ containing eight anthraquinone groups as binding sites, were developed for very accurate and sensitive detection of Fe³⁺ metal ion. The motivation for this study lies in the need for advanced sensing techniques for precisely identifying Fe³⁺ ions. Due to its unique redox properties, Fe³⁺ plays a crucial role in biological processes, environmental remediation, medical diagnostics, and advanced detection methods. The sensors were extensively characterized using FT-IR, ¹H NMR, ¹³C NMR, and ESI-MS techniques. The absorption spectra revealed significant interactions between RES-AAQ and Fe³⁺ ions. Fluorescence quenching was observed due to Photoinduced electron transfer (PET). The quenching process was systematically analyzed using Stern-Volmer analysis. Each sensor (L₁, L₂, L₃, L₄) demonstrated remarkable detection limits for Fe³⁺ ions (10.51 nM, 10.48 nM, 10.49 nM, 10.47 nM, respectively) along with substantial binding affinities (binding constants: 9.07x10⁹ M^-1, 1.19x10⁹ M^-1, 1.49x10⁹ M^-1 and 1.03x10⁹ M^-1 for L₁, L₂, L₃, and L₄, respectively). Traditional, Fe³⁺ detection methods often suffer from limitations such as complexity, lack of sensitivity, or interference from other metal ions. This research offers highly sensitive fluorescent sensors for Fe³⁺ detection with potential applications in human blood serum and tap water. Molecular docking, DFT studies, and ESI-MS investigation have been employed to gain insights into the binding interactions between the molecules. The low detection limits, high binding affinity, and real-world applicability highlight the significant advantages of developed sensors compared to existing methods. Additionally, a combinatorial logic gate was constructed to facilitate a proper understanding of the working principle of RES-AAQ.