Herein, we report a novel synthetic pathway for synthesizing bis‐coumarins using 5 mol% [BCMIM][Cl] ionic liquid via the facile, one‐pot, metal‐free synthesis in aqueous ethanol at room temperature. A series of 24 derivatives were furnished in up to 94% yields in 15 min to 1.5 h and were characterized using different spectroscopic techniques. The photophysical properties of bis‐coumarin derivatives were explored through UV‐Visible and fluorescence spectroscopy. The absorption and emission spectra demonstrate a peak wavelength (λmax), within the range of 297–311 nm and 486–505 nm, respectively. An analogous pattern to the experimental results is seen in density functional calculations. The binding affinities of all the synthesised derivatives with Bovine Serum Albumin (BSA) were determined using AutoDock Vina which exhibited a range from −8.4 to −11.5 kcal mol−1. The computed binding constant (KBSA) by tryptophan (Trp) emission quenching values illustrate strong binding interactions of the selected ligands in the order of 104. The calculated binding affinities were validated by performing molecular dynamics simulations of the best docking pose using GROMACS software over a period of 1 ns for studying the stability of protein‐ligand complexes.

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High selectivity and sensitivity detection of Hg 2 + in aqueous environment by the naked-eye has always been a challenge. In this paper, a simple ligand based on 2-(hydroxymethyl)quinolin-8-ol (L) was synthesized and its structure was confirmed by NMR, IR and mass analysis. The probe L showed distinct colorimetric upon interaction with Hg 2 + in CH 3 OH-H 2 O (8 : 2, v/v) media. The ligand L exhibit unique absorbance band at 243 nm due to ligand-to-ligand charge transfer (LLCT). Upon interaction with Hg 2 + , the L formed new UV-Vis bands at 269 and 316 nm due to ligand-to-metal charge transitions (LMCT). The UV-Vis spectral studies indicate the formation of a 1 : 1 host-guest complex between the L and Hg 2 + with an association constant of 8.6 × 10 4 M À 1. The ligand L can work in the pH range of 3-8 without interfering with other competing ions. The detection limit of Hg 2 + can reach a concentration of as low as 0.13 μM (2.6 ppb) with high selectivity, even in a solution containing diverse metal ions. Besides, the selective colour change of L with Hg 2 + was integrated with smartphone to monitor the change in RGB tool and test paper kit. The binding mechanism of L with Hg 2 + was studied by using 1 H NMR, SEM and TDDFT analysis. Overall, ligand L demonstrates a promising and potential for the detection of toxic contaminate in aqueous environment.