Facile Synthesis of Bis‐Coumarins Using [BCMIM][Cl] Zwitter Ionic Liquid and Their Binding with Bovine Serum Albumin

Abstract

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.