Density functional theory study of the potassium complexation of an unsymmetrical 1,3-alternate calix[4]-crown-5-N-azacrown-5 bearing two different crown rings.
Theoretical studies of an unsymmetrical calix[4]-crown-5-N-azacrown-5 (1) in a fixed 1,3-alternate conformation and the complexes 1·K(+)(a), 1·K(+)(b), 1·K(+)(c) and 1·K(+)K(+) were performed using density functional theory (DFT) at the B3LYP/6-31G level. The fully optimized geometric structures of the free macroligand and its 1:1 and 1:2 complexes, as obtained from DFT calculations, were used to perform natural bond orbital (NBO) analysis. The two main types of driving force metal-ligand and cation-π interactions were investigated. NBO analysis indicated that the stabilization interaction energies (E (2)) for O…K(+) and N…K(+) are larger than the other intermolecular interactions in each complex. The significant increase in electron density in the RY or LP orbitals of K(+) results in strong host-guest interactions. In addition, the intermolecular interaction thermal energies (ΔE, ΔH, ΔG) were calculated by frequency analysis at the B3LYP/6-31G level. For all structures, the most pronounced changes in the geometric parameters upon interaction are observed in the calix[4]arene molecule. The results indicate that both the intermolecular electrostatic interactions and the cation-π interactions between the metal ion and π orbitals of the two pairs that face the inverted benzene rings play a significant role.
Key Laboratory of Environmentally Friendly Chemistry, College of Chemistry, Xiangtan University, Xiangtan, Hunan 411105, People's Republic of China.
Xiaoyan
X
Zheng
Xueye
X
Wang
Keqi
K
Shen
Yuan
Y
Miao
Dan
D
Ouyang
D047248:Crown Compounds / Q000737:chemistry*; D008956:Models, Chemical; D008968:Molecular Conformation; D011188:Potassium / Q000737:chemistry*
D047248:Crown Compounds; D011188:Potassium
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