Calix[4]arene as an efficient framework for environmental remediation of water bodies from chloro- and fluorocarbons

Abstract

Chloro- and fluorocarbon are toxic chemical compounds which pose significant threats to both human health and the environment, making their rapid detection and effective removal crucial. While macrocyclic calix[4]arenes (CX[4]) are well-known for their applications in energy storage and optoelectronics, their potential as a host for capturing chemicals remains underexplored. In this study, the sensing ability and selectivity of CX[4] macrocycles are theoretically investigated against a range of toxic environmental pollutants, including CCl₄, CH₃Cl, CH₂Cl₂, CF₃Cl, CF₄, C₂F₆, and CF₃Br. The host–guest interactions between CX[4] and these freon-type compounds are analyzed by using various approaches including computing the interaction energies, natural bond orbital (NBO) analysis, frontier molecular orbitals (FMO), non-covalent interaction (IRI) plots, and quantum theory of atoms in molecules (QTAIM). Results indicate that the central cavity of CX[4] serves as a favorable binding site. The calculated interaction energies demonstrate the thermodynamic stability of the resulting inclusion complexes. Additionally, the HOMO–LUMO energy gaps (E_H–L) are evaluated to assess the kinetic stability and reactivity of the complexes. Among the tested pollutants, chlorinated compounds, particularly CHCl₃ and CCl₄, established the strongest interaction with CX[4] as shown by the corresponding interaction energies (−64.57 kJ mol⁻¹ and −60.16 kJ mol⁻¹, respectively). The various computational analyses confirm that these interactions are predominantly governed by non-covalent forces. Overall, this theoretical investigation provides valuable insights for developing CX[4]-based materials which can serve as effective host for remediation of hazardous pollutants, potentially capable of operating efficiently even in humid conditions.