Ab initio and density functional theoretical design and screening of model crown ether based ligand (host) for extraction of lithium metal ion (guest): effect of donor and electronic induction
Ab initio and density functional theoretical design and screening of model crown ether based ligand (host) for extraction of lithium metal ion (guest): effect of donor and electronic induction
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DOI：
10.1007/s00894-011-1348-1
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发表时间：
2012-02
影响因子：
2.2
通讯作者：
A. Boda;S. Ali;H. Rao;Sandip Ghosh
中科院分区：
文献类型：
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作者：
A. Boda;S. Ali;H. Rao;Sandip Ghosh
利用从头MP2和密度泛函理论在气相和溶剂相中确定了具有不同供体、空腔和给/吸电子官能团的模型冠醚的结构、能量和热力学参数。与基于软供体的硫杂和磷冠相比，基于硬供体的氮杂和氧杂冠的锂离子络合的结合能/焓的计算值略高。理论MP2水平下锂金属离子与12C4的结合热计算值与现有实验结果吻合较好。由于冠醚中的给电子/吸电子基团所赋予的诱导效应，结合能发生改变，这与电子转移值密切相关。已经证明了熵对于通过不同的供体和基于官能团的配体萃取水合锂金属离子的作用。由于溶剂的介电常数，从气相到有机相，HOMO-LUMO间隙减小，配体的偶极矩增大。当溶剂分子削弱金属-配体结合时，气相结合能在溶剂相中降低。实验趋势验证了不同有机溶剂中LiCl盐从水溶液中萃取能的理论值。这里提出的研究应该有助于模型主体配体的设计和金属离子识别溶剂的筛选，从而有助于规划实验。图Ab B12C4-CH3冠醚从水介质中萃取锂离子到硝基苯的起始模型
The structures, energetic and thermodynamic parameters of model crown ethers with different donor, cavity and electron donating/ withdrawing functional group have been determined withab initioMP2 and density functional theory in gas and solvent phase. The calculated values of binding energy/ enthalpy for lithium ion complexation are marginally higher for hard donor based aza and oxa crown compared to soft donor based thia and phospha crown. The calculated values of binding enthalpy for lithium metal ion with 12C4 at MP2 level of theory is in good agreement with the available experimental result. The binding energy is altered due to the inductive effect imparted by the electron donating/ withdrawing group in crown ether, which is well correlated with the values of electron transfer. The role of entropy for extraction of hydrated lithium metal ion by different donor and functional group based ligand has been demonstrated. The HOMO-LUMO gap is decreased and dipole moment of the ligand is increased from gas phase to organic phase because of the dielectric constant of the solvent. The gas phase binding energy is reduced in solvent phase as the solvent molecules weaken the metal-ligand binding. The theoretical values of extraction energy for LiCl salt from aqueous solution in different organic solvent is validated by the experimental trend. The study presented here should contribute to the design of model host ligand and screening of solvent for metal ion recognition and thus can contribute in planning the experiments.FigureAb initiomodeling for extraction of Li ion from aqueous medium to nitrobenzene by B12C4-CH3crown ether