A theoretical insight into several common anion recognitions based on double‐dentate hydrogen bond and anion‐π coexistence

Abstract

AbstractAnion recognitions of a pincer‐like receptor (N,N'‐bis‐(2‐fluoro‐benzoyl‐oxyethyl)‐urea, AR) for several common inorganic anions (F−, Cl−, Br−, I−, CN−, and SO42−) were theoretically explored and predicted at a molecular level in this paper. Geometric configurations of the complex (AR@X (X = F−, Cl−, Br−, and SO42−)) show that two N─H groups as a claw and two ─C6H4F rings on AR as a pair of tweezers simultaneously interact with the captured anions through cooperative double‐dentate hydrogen bond and double‐side anion‐π interactions. However, there is no anion‐π contact between AR and I− ion in AR@I− complex. In the system of AR@CN−, a stable single‐side CN−‐π is possible. The structure of stable 2:1 complex formed with two AR receptors and one SO42− is also predicted. The binding energies and thermodynamic information indicate that the recognitions of the above six anions by AR in the vacuum are spontaneously enthalpy‐driven and entropy‐opposed. The binding energy ΔEcp between SO42− and AR is higher than 340 kJ mol−1, suggesting that AR is an ideal selective anion receptor for 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, and visualized weak interaction regions.