DFT Study for a Series of Less‐Symmetrical Crown Ethers and Their Complexes with Alkali Metal Cations

Abstract

A series of ring-contracted (14-crown-5, 17-crown-6) and ring-enlarged (16-crown-5, 17-crown-5, 19-crown-6, 20-crown-6) crown ethers and their complexes with alkali-metal cations Na ＋ and K ＋ had been explored using density functional theory (DFT) at B3LYP/6-31G* level in order to reveal the effects of the methylene-chain length in a crown ether. The nucleophilicity of all crown ethers had been investigated by the Fukui functions. The quantum chemistry parameters, such as the energy gap (∆E), the highest occupied molecular orbital energy (E HOMO ) and the lowest unoccupied molecular orbital energy (E LUMO ) for less-symmetrical crown ethers and symmetrical frameworks (15-crown-5, 18-crown-6) had been calculated. In addition, the thermodynamic energies of complexation reactions had also been studied. The results of the DFT calculations show that the methylene-chain length plays an important role in determining the structure characters of the crown ethers and also strongly influences the properties of the ethers. Some of the calculated results are in a good agreement with the experimental values.

Synthesis, Metal Ion Complexation and Computational Studies of Thio Oxocrown Ethers

“…Various quantum-chemical and force-field computations of crown ethers and of their metal complexes have been reported recently [24,26,27,28], even on the ab initio level [29,30] and the density functional level of theory (DFT) [31,32,33]. The structures of molecules play an especially significant role in determining their chemical properties.…”

New Insights on the Mechanism of Thermal Cleavage of Unsaturated Bicyclic Diaziridines: A DFT Study

“…Using Gaussian 98 program and McGrath basis set, 22 Curtiss included the (6-311＋＋G (3df, 2p)) diffuse functions through density functional theory (UB3LYP), 23,24 using the Becke three-parameter exchange functional 25 and Lee, Yang, and Parr nonlocal correlation functional to obtain more accurate values of structures and energy. 26 DFT is selected among all methods as it is less common to find any significant spin contamination in DFT calculations, even when unrestricted Kohn-Sham orbitals are used.…”