CIESC Journal ›› 2020, Vol. 71 ›› Issue (S1): 15-22.DOI: 10.11949/0438-1157.20191380

• Thermodynamics • Previous Articles     Next Articles

Structure and hydrogen bonding study on acylamino acid protic ionic liquids composed of 2-N-ethylhexylethylenediaminim cation with acylalanineate anions

Jiaxin LIU1(),Yu XU1,Er HUA1,2,3()   

  1. 1.College of Chemistry and Chemical Engineering, North Minzu University, Yinchuan 750021, Ningxia, China
    2.Key Laboratory of Chemical Engineering and Technology, State Ethnic Affairs Commission, North Minzu University, Yinchuan 750021, Ningxia, China
    3.Ningxia Key Laboratory of Solar Chemical Conversion Technology, North Minzu University, Yinchuan 750021, Ningxia, China
  • Received:2019-11-13 Revised:2019-12-19 Online:2020-04-25 Published:2020-04-25
  • Contact: Er HUA

异辛基乙二胺-酰基丙氨酸型质子化离子液体的分子间氢键相互作用

刘佳鑫1(),徐宇1,花儿1,2,3()   

  1. 1.北方民族大学化学与化学工程学院,宁夏 银川 750021
    2.北方民族大学国家民委化工技术基础重点实验室,宁夏 银川 750021
    3.北方民族大学宁夏太阳能化学转化技术重点实验室,宁夏 银川 750021
  • 通讯作者: 花儿
  • 作者简介:刘佳鑫(1995—),女,硕士研究生,937979876@qq.com
  • 基金资助:
    北方民族大学科技创新类重点科研项目(2019 KJ13)

Abstract:

The possible molecular structures S1—S5 of acylamino acid protic ionic liquids (AA-PILs) composed of 2-N-ethylhexylethylenediaminium cation coupled with acylalanineate anions forming [HEtHex][Acylala] were studied by the density functional theory at M06-2X/6-311G (d,p) level. The obtained BSSE-corrected interaction energies (ΔE0BSSE) for all the structures are in the region of -136.14~-117.26 kcal?mol-1. For each PIL, the values of ΔE0BSSE in the [HEtHex]1+[Acylala]- (S1—S3, protonated at the primary amine, -136.14—-127.01 kcal·mol-1) are larger than in the [HEtHex]2+[Acylala]- structures (S4 and S5, protonated at the secondary amine, -119.03—-117.26 kcal·mol-1). The IR results show that N—H vibration spectra is disappeared. In the meantime, the stronger O—H vibration spectra appeared in the region of 2400—2815 cm-1 since stronger O—H…N hydrogen bond was formed between [HEtHex] molecule and [Acylala] molecule. The results of natural bond orbital the stabilization energy mainly caused by the interaction between the lone pair electron lp(N) in the [EtHex] and the anti-bonding orbital σ*(O—H) in the [Acylala]: lp(N)→σ*(O—H). The hydrogen bonding energy and the second-order interaction energies are in the range of 18.69—24.19 kcal·mol-1 and 43.58—57.58 kcal?mol-1, respectively. H-bonding between [HEtHex] and [Acylala] is classified as the strong hydrogen bond.

Key words: acylamino acid protic ionic liquids, density functional theory, proton transfer, inter molecular hydrogen bonding

摘要:

利用密度泛函理论M06-2X/6-311G(d,p)方法及基组条件下,对异辛基乙二胺-酰基丙氨酸型质子化离子液体[HEtHex]+[Acylala]-(Acyl =butanoyl, hexanoyl)的几何构型进行了优化,分别得到了5种较稳定构型S1~S5。结果显示,[HEtHex][Butlala]及[HEtHex][Hexlala]的基组重叠误差校正后的分子间相互作用能(ΔE0BSSE)均在-136.14~-117.26 kcal·mol-1(1 kcal·mol-1=4.182 kJ·mol-1)范围内,其中伯胺质子化构型(S1~S3)的相互作用能(-136.14~-127.01 kcal·mol-1)大于仲胺质子化构型(S4~S5)(-119.03~-117.26 kcal·mol-1)。由于[HEtHex][Acylala]阴阳离子间发生了质子转移而形成了较强的O—H…N型氢键,引起[HEtHex]+中N—H振动频率消失,并在2400~2815 cm-1处出现了较强的O—H的伸缩振动,即以分子与分子间的作用力键合。自然键轨道及分子中原子理论计算结果显示,[HEtHex][Acylala]间所形成氢键的稳定化能主要来源于[EtHex]分子中胺基N原子的孤对电子lp(N)与[Acylala]分子中羧基的反键轨道σ*(O—H)间的相互作用。并且分子间氢键能及二阶微扰能分别在18.69 ~ 24.19 kcal·mol-1及43.58 ~57.58 kcal?mol-1范围内,属于较强类型氢键作用。

关键词: 酰基氨基酸离子液体, 密度泛函理论, 质子转移, 分子间氢键作用

CLC Number: