Vibrational Analysis of Azacrown Ether Complex with Li Metal Cation

Bulletin of the Korean chemical society

Chang Suk Kim¹  Choongkeun Lee¹  Kyung Chul Min¹  Sun Kyung Park¹  Nam Soo Lee¹ 

关键词: Azacrown ether;    Li metal cation complex;    Vibrational analysis;    Dynamic effects;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

Li⁺ ion complex of azacrown ether with restricted motion of freedom and pseudo-bilateral symmetry was studied by infrared spectroscopy, which has shown simplified and broadened vibrational features. The C=O and N-H stretching bands, in particular, shows anomalous broadening nearly ~150 cm^-1. The density functional calculation at the level of BP86/6-31+G** shows that Li⁺ ion is trapped and rather free to move around inside the cavity, as much as about 0.70 A. Through the relocation of Li⁺ ion inside the cavity, the conformational changes would occur rapidly in its symmetry C₁ ? C₂ ? C₁. The potential barrier was obtained to be merely ~2.2 kJ/mol for C₁ �? C₂. During this conformational alteration, the amide backbone twists concurrently its dihedral angle side to side about up to �?3 degree. Selected vibrational modes were interpreted in terms of the force constant variations of local symmetry coordinates between conformations in the framework of C1 ? C2 ? C1.

【 授权许可】

Unknown