DFT study of crown ether-bridged Z-stilbenes and their complexes with alkali metal cations

A density functional theory (DFT) based on the interaction of alkali metal cations (Li+, Na+, K+, Rb+ and Cs+) with crown ether-bridged Z-stilbene has been investigated. The minimum energy structures, binding energies, and various thermodynamic parameters of free ligands and their metal cations complexes have been determined with B3LYP functional using mixed basis set (C, H, O, Li+, Na+ and K+ using 6-31+G(d), and the heavier cations: Rb+ and Cs+ using LANL2DZ). The optimized geometric structures are performed natural bond orbital (NBO) analysis. The main types of driving force host–guest interactions are investigated, the electron-donating O offers lone pair electrons to the contacting LP* (1-center valence lone pair) of alkali metal cations. In addition, the maximum absorption wavelength is studied on the time-dependent density functional theory (TD-DFT), the calculated results indicate that the wavelength is blue shifted when alkali cations incorporating into the ether rings. It is found that the crown ether-bridged Z-stilbene is good candidate for moderate alkali metal cations’ recognition regent.