物理化学学报2021，Vol.37Issue(10)：57-66,10.DOI:10.3866/PKU.WHXB202002021
咪唑类离子液体与酪氨酸相互作用及机理的密度泛函理论研究
Interaction and Mechanism between Imidazolium Ionic Liquids and the Zwitterionic Amino Acid Tyr:a DFT Study
摘要
Abstract
Ionic liquids (ILs) are thermally and chemically stable and have adjustable structures,which gives them the potential to be used as green,efficient biomolecular solvents.Given the critical role of ILs in dissolving biomolecules,the mechanism of interaction between them deserves further study.Herein,density functional theory (DFT)calculations,using the SMD implicit water solvent model,were employed to study the interaction and mechanism between a hydrophobic zwitterionic amino acid (Tyr) and a series of imidazolium ILs with different alkyl chain lengths and methylation sites.The contributions of hydrogen bonding (H-bonding),electrostatic effects,induction,and dispersion to the intermolecular interactions were determined by combining the symmetry-adapted perturbation theory (SAPT),the atoms in molecules (AIM) theory,and reduced density gradient (RDG) analysis.The results indicate that the H-bonding between the IL cation and Tyr is stronger than that between the IL anion and Tyr;however,the binding between either ion and Tyr is dominated by electrostatic effects.By contrast,the difference between the induction and dispersion forces is small when methylation occurs on the C2 site of the imidazolium cation;whereas,it is significantly large when methylation takes place on the N3 site.This is rationalized by the interaction patterns that vary based on the methylation site.H-bonding and π+-π stacking interactions between the imidazole and benzene rings are dominant during C2-methylation,while H-bonding and CAlkyl-H… π interactions between the alkyl chain and benzene ring are dominant during N3-methylation.Increasing the side alkyl chain length has different effects on the interaction energy to cations with different methylation sites.During N3-methylation,when the side alkyl chain length increases from 4 to 12,there are significant van der Waals interactions between the Tyr benzene and the side alkyl chain.However,these van der Waals interactions are inapparent when methylation takes place on the C2 site.Finally,the synergetic effect of the H-bonding and the interaction between the benzene and the side alkyl chain for C2-methylation is greater than the H-bonding and the interaction between the imidazole and benzene rings for N3-methylation,when the side alkyl chain length n ＞ 9.Therefore,the interaction strength and mechanism in these imidazolium-Tyr complexes can be regulated by changing the methylation site and the side alkyl chain length of the cation.Further study of ion-pair and Tyr reveals that the change tendency of the interaction energy of IL-Tyr systems is consistent with that of cation-Tyr cases,and the ion pair further stabilizes the binding with Tyr.These results illustrate the interaction mechanism of IL-Tyr systems and provide a novel strategy for the design and screening of functional ILs for amino acid extraction and separation in the future.关键词
离子液体/两性离子型氨基酸/相互作用机理/氢键作用/范德华相互作用Key words
Ionic liquids/Zwitterionic amino acid/Interaction and mechanism/Hydrogen bond effect/Van der Waals effect分类
化学化工引用本文复制引用
吴智伟,丁伟璐,张雅琴,王艳磊,何宏艳..咪唑类离子液体与酪氨酸相互作用及机理的密度泛函理论研究[J].物理化学学报,2021,37(10):57-66,10.基金项目
This work was supported by the National Science Fund for Excellent Young Scholars,China (21922813),Key Program of National Natural Science Foundation of China (21834006),General program of National Natural Science Foundation of China (21978027),Key Research Program of Frontier Sciences of CAS(QYZDB-SSW-SLH022),and Youth Innovation Promotion Association of CAS (2017066).国家自然科学基金优秀青年科学基金(21922813),国家自然科学基金重点项目(21834006),国家自然科学基金面上项目(21978027),中国科学院前沿科学重点研究计划(QYZDB-SSW-SLH022),中国科学院青年创新促进会(2017066)资助项目 （21922813）
