Density functional theory study of calix[4]arene‐N‐azacrown‐5, calix[4]arene‐N‐phenyl‐azacrown‐5, and their complexes with alkali‐metal cations: Na⁺, K⁺, and Rb⁺

Abstract

Theoretical studies of 1,3-alternate-25,27-bis(1-methoxyethyl)calix[4]arene-azacrown-5 (L(1)), 1,3-alternate-25,27-bis(1-methoxyethyl)calix[4]arene-N-phenyl-azacrown-5 (L(2)), and the corresponding complexes M(+)/ L of L(1) and L(2) with the alkali-metal cations: Na(+), K(+), and Rb(+) have been performed using density functional theory (DFT) at B3LYP/6-31G* level. The optimized geometric structures obtained from DFT calculations are used to perform natural bond orbital (NBO) analysis. The two main types of driving force metal-ligand and cation-pi interactions are investigated. The results indicate that intermolecular electrostatic interactions are dominant and the electron-donating oxygen offer lone pair electrons to the contacting RY* (1-center Rydberg) or LP* (1-center valence antibond lone pair) orbitals of M(+) (Na(+), K(+), and Rb(+)). What's more, the cation-pi interactions between the metal ion and pi-orbitals of the two rotated benzene rings play a minor role. For all the structures, the most pronounced changes in geometric parameters upon interaction are observed in the calix[4]arene molecule. In addition, an extra pendant phenyl group attached to nitrogen can promote metal complexation by 3D encapsulation greatly. In addition, the enthalpies of complexation reaction and hydrated cation exchange reaction had been studied by the calculated thermodynamic data. The calculated results of hydrated cation exchange reaction are in a good agreement with the experimental data for the complexes.

Molecular Dynamics Simulation and Density Functional Theory Investigation for Thiacalix[4]biscrown and its Complexes with Alkali-Metal Cations

“…The contribution of the cation-π interaction holds a minor contribution on metal binding, which is in agreement with the previous report on similar systems. 33 Since the K + ion is recognized by one side of the complex, the dipole moment of the 3+K + complex is computed to be 6.3 D which is quite large compared to 0.8 D for the free host 3.…”

Computational Design of Two-Photon Fluorescent Probes for Intracellular Free Zinc Ions

“…As everyone knows, the sensitivity and possibility of the probe molecule and metal ion binding can be assessed though the binding energy, binding enthalpy, and Gibbs free energy. − Table clearly shows that the Δ E values of the probe molecules for Zn 2+ are larger than those of Na + , K + , and Ca 2+ , so these probe molecules are more sensitive to Zn 2+ and Mg 2+ . The values of Δ H and Δ G for Zn 2+ coordination reaction are much larger than those for Na + , K + , and Ca 2+ , respectively, which means that probe molecules have a better binding possibility for the zinc and magnesium ions.…”