Indexed on: 07 Jan '17Published on: 07 Jan '17Published in: Journal of Physical Chemistry A
Anion recognitions between common anions and a novel pincer-like receptor (N, N'-bis-(five-fluoro-benzoyl-oxyethyl)-urea, BFUR) were theoretically explored, particularly on geometric features of the BFUR@X (X = F-, Cl-, Br-, I-, CO32-, NO3- and SO42-) systems at a molecular level in this work. Complex structures show that two N-H groups as a claw and two -C6F5 rings on BFUR as a pair of tweezers simultaneously interact with captured anions through cooperative double-dentate hydrogen bond and double-side anion-π interactions. The binding energies and thermodynamic information indicate that the recognitions of the seven anions by BFUR in the vacuum are enthalpy-driven and entropy-opposed, which occur spontaneously. Although binding energy ΔEcp between F- and BFUR is relatively high (289.30 kJ•mol-1), ΔEcp, ΔG and ΔH of the recognition for CO32- and SO42- are much larger than the cases of F-, Cl-, Br-, I- and NO3-, suggesting BFUR an ideal selective anion receptor for CO32- and SO42-. Additionally, energy decomposition analysis based on localized molecular orbital energy decomposition analysis (LMO-EDA) was performed; electronic properties and behaviors of the present systems were further discussed according to calculations on frontier molecular orbital, UV-vis spectra, total electrostatic potential and visualized weak interaction regions. The present theoretical exploration of BFUR@X (X=F-, Cl-, Br-, I-, CO32-, NO3- and SO42-) systems is fundamentally crucial to establish anion recognition structure-property relationship upon combination of different noncovalent interactions, i.e. double-dentate hydrogen bond and double-side anion-π interactions.