@article{oai:ynu.repo.nii.ac.jp:00009420,
 author = {Tsuchida, Yusuke and Matsumiya, Masahiko and Tsunashima, Katsuhiko},
 journal = {Journal of Molecular Liquids},
 month = {Jan},
 note = {Transport property such as conductivity and viscosity is important factor in designing ionic liquids (ILs). Depending on substituent type in ILs, the transport property is known to easily changeable. Introduction of a benzyl or a cyano group lowers the transport property, however in the case of a methoxy or an allyl group, the transport property is improved. It is important to reveal the static property with different substituents on the phosphonium-based ILs from the viewpoint of the microscopic analysis by theoretical calculation. For this purpose, we investigated the charge distribution, interaction with counter anion and torsional potential for different substituents on the phosphonium-based ILs in this study. From the MP2/6-311G⁎⁎ calculation, the atomic charge of the phosphorus atom on the P4444+ cation was 0.57 and it was higher than that of nitrogen atom (0.14) on the corresponding ammonium cation (N4444+). The charge distributions with different substituents such as P444(3Bz), P444(3CN), P444(2Al) and P444(2O1) were also revealed in this study. According to the analysis of the torsion potential with different substituents, the methoxy substituted cations which would lead to the good transport property were stable at a torsional angle of 180° and the allyl substituted cations were stable at 120° and 240°. On the other hand, it was found that the benzyl and the cyano substitution type cations, which were known as lower transport properties, were most stable at torsional angles of 60° and 300°. Furthermore, it was revealed that the rotational barriers of the dihedral angular potential of the methoxy and the allyl group are smaller than those of the cyano and the benzyl group. Moreover, from the calculated optimized geometry and the interaction energy of the cations containing various substituents, the gain (Eint) of the energy obtained by cluster formation in the ammonium cation was larger than that in the phosphonium cation. A series of the MP2 calculation results enabled us to indicate that the phosphonium cation had a higher affinity for the anion than the corresponding ammonium cation and the effect of the substituent on ionic interaction was not so influenced on each transport property.},
 pages = {455--460},
 title = {The effect of substituents of phosphonium-based ionic liquids evaluated by MP2 calculation},
 volume = {274},
 year = {2019}
}