A TD-DFT study on photoswitchable chloride salts receptor based on acylhydrazone and crown ether embedded Macrocyclic molecule

Abstract

The physical method of remediating saline-alkali soil, flushing soil drainage, and extracting lithium ions from salt lakes require tons of ion pair receptors with high selectivity to salts and reusability for the purpose of water conservation. The photoswitchable ion pair receptor is much fascinating if the ion pair receptor possesses two controllable states, namely capture state and release state. Using LiCl, NaCl, KCl as target ion pairs, two crown ether embedded cyclic receptors were computationally designed by introducing ether chain into a acylhydrazone photoswitch. The affinities to XCl of the designed receptors were observed by calculation binding energy and molecular topologic analysis. The photochemical properties of the receptors were observed by simulating UV–Vis absorption spectra according to the TD-DFT calculation results. Only the receptor 1 shows obviously different affinity to XCl ion pairs. The binding energies of Z-1 and XCl are reduced by about 7 kcal•mol-1, or about 50%. The binding of XCl has almost no effect on the photochemical properties of E-1. The designed 1 is therefore a XCl ion pair receptor worthy of further study to meet the great needs in the field of chloride salts extraction.