**4. Conclusions**

The interaction behavior of (1:1) estrone and imidazolium-based hydrophobic ionic liquids such as [BMIM]<sup>+</sup> [NTF2]<sup>−</sup>, [BMIM]<sup>+</sup> [PF6]<sup>−</sup>, and [BMIM]<sup>+</sup> [BF4]<sup>−</sup> was studied at the B3LYP/6-31G(d) level of theory. The optimized structures were presented to study the vicinity of EDC with respect to each ionic liquid. The ZPE-corrected binding energy values were found to be negative, indicating fruitful interaction of the EDC and ionic liquid species. Based on the interaction strength, the affinity of estrone on ionic liquids can be described as [BMI M]<sup>+</sup> [PF6]<sup>−</sup> > [BMIM]<sup>+</sup> [BF4]<sup>−</sup> > [BMIM]<sup>+</sup> [NTF2]<sup>−</sup>. AIM analYsis was carried out to find the nature of interactions, so as to get the electronic distribution at the intermolecular region. It was found out that all interactions were characterized by positive Laplacian of electron density and −G(rc)/V(rc) > 1 at intermolecular critical points illuminating the non-covalent nature of interactions existing between EDC and ionic liquids.

*Advances in Quantum Communication and Information*
