Design and Synthesis of Novel Coumarin-Isoxazole Conjugates as Chemosensers: A Highly Selective and Instantaneous Detection of Mn

This study demonstrates the synthesis and characterization of a series of novel isoxazole-containing 4-hydroxycoumarin-based chemosensors for the highly selective and rapid detection of Mn2+ and Cu2+ ions from among several metal ions in DMSO: EtOH (1:9 v/v). The probes were synthesized using inexpensive and readily available starting materials and were structurally characterized by 1H and 13C NMR, FT-IR, HRMS, and SC-XRD spectroscopic analyses. UV-Vis, fluorescence studies, and X-ray crystallography revealed a significant binding interaction with Cu2+ and Mn2+, leading to pronounced spectral shifts. Fluorescence studies demonstrated strong fluorescence enhancement for Mn2+, whereas Cu2+ exhibited quenching behavior. The calculated binding constant for the 8f-Mn2+ complex was 1.2233 × 107 M-1 and for the 8f-Cu2+ complex was 5.4647 × 107 M-1. Again, the calculated limit of detection (LOD) for Mn2+ and Cu2+ with respect to the ligand 8f was 2.697552 × 10-7 M and 0.60491 × 10-7 M respectively, indicating high sensitivity. The fluorescence variations in 8f with two chemical inputs, Mn2+ and Cu2+, can be utilized to create a molecular circuit demonstrating an INHIBIT logic operation based on studies. The competitive selectivity experiments confirmed the ligand's superior affinity towards Mn2+ in the presence of various metal ions.