González-Veloso Iván, Figueiredo Nádia M, Cordeiro M Natália D S
LAQV@REQUIMTE, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal.
Molecules. 2021 Sep 11;26(18):5526. doi: 10.3390/molecules26185526.
This work aims at unravelling the interactions in magnetic ionic liquids (MILs) by applying Symmetry-Adapted Perturbation Theory (SAPT) calculations, as well as based on those to set-up a polarisable force field model for these liquids. The targeted MILs comprise two different cations, namely: 1-butyl-3-methylimidazolium ([Bmim]) and 1-ethyl-3-methylimidazolium ([Emim]), along with several metal halides anions such as [FeCl], [FeBr], [ZnCl] and [SnCl] To begin with, DFT geometry optimisations of such MILs were performed, which in turn revealed that the metallic anions prefer to stay close to the region of the carbon atom between the nitrogen atoms in the imidazolium fragment. Then, a SAPT study was carried out to find the optimal separation of the monomers and the different contributions for their interaction energy. It was found that the main contribution to the interaction energy is the electrostatic interaction component, followed by the dispersion one in most of the cases. The SAPT results were compared with those obtained by employing the local energy decomposition scheme based on the DLPNO-CCSD(T) method, the latter showing slightly lower values for the interaction energy as well as an increase of the distance between the minima centres of mass. Finally, the calculated SAPT interaction energies were found to correlate well with the melting points experimentally measured for these MILs.
这项工作旨在通过应用对称适应微扰理论（SAPT）计算来揭示磁性离子液体（MILs）中的相互作用，并在此基础上为这些液体建立一个可极化的力场模型。目标MILs包含两种不同的阳离子，即：1-丁基-3-甲基咪唑鎓（[Bmim]）和1-乙基-3-甲基咪唑鎓（[Emim]），以及几种金属卤化物阴离子，如[FeCl]、[FeBr]、[ZnCl]和[SnCl]。首先，对这类MILs进行了DFT几何优化，结果表明金属阴离子更倾向于靠近咪唑鎓片段中氮原子之间的碳原子区域。然后，进行了SAPT研究，以找到单体的最佳分离以及它们相互作用能的不同贡献。结果发现，对相互作用能的主要贡献是静电相互作用分量，在大多数情况下其次是色散相互作用分量。将SAPT结果与基于DLPNO-CCSD(T)方法的局部能量分解方案得到的结果进行了比较，后者显示相互作用能的值略低，并且质心最小值之间的距离有所增加。最后，发现计算得到的SAPT相互作用能与这些MILs的实验测量熔点有很好的相关性。
