Theoretical characterizations on three oxygen-containing polyatomic anion binding of the single/double pincer-like...

In this paper, density functional theory calculations were used to systematically characterize the binding behavior of the two types of pincer-like receptors with different configurations (E-type and Z-type) to three oxygen-containing polyatomic anions (SO₄^2-, C₂O₄^2- and NO₃^-). The E-type receptor (2ENH₂) shows slightly preferential binding of SO₄^2-. Independent gradient model based on Hirshfeld partition (IGMH) analysis characterized the non-covalent interaction patterns between the receptor and anion. Meanwhile, molecular electrostatic potential (ESP) analysis revealed changes in charge distribution upon anion binding. UV-Vis spectra and ¹H NMR calculations provided complementary information on the electronic and structural changes induced by complexation between anion and receptor. In addition, ab initio molecular dynamics (AIMD) simulations were used to examine the structural persistence of representative host-guest complexes. Overall, the results clarify how receptor configuration, hydrogen-bonding topology, anion properties, and solvent environment collectively influence anion recognition.

All geometries were optimized at the B3LYP-D3BJ/def2-SVP level of theory without any symmetry constraints. The host-guest binding energies (ΔE_b^cp) were corrected for basis set superposition error (BSSE). Additional calculations using B3LYP-D3BJ/def2-TZVP with counterpoise correction were performed for selected complexes to assess the robustness of the binding energies. Wave function analyses were performed using the Multiwfn program. AIMD simulations were using the ORCA 5.0 program with the composite method of B97-3c developed by Grimme and coworkers. All other calculations were performed using the Gaussian 16 program.