N-月桂酰基-L-丙氨酸分子组装结构的固体核磁共振研究  

Insight of N-Lauroyl-L-alanine Molecular Assembly Using Solid-State Nuclear Magnetic Resonance Technique

作　　者：裘子慧 徐凌云 陈伊健 董洪春 舒婕 姚志刚 QIU Zi-Hui;XU Ling-Yun;CHEN Yi-Jian;DONG Hong-Chun;SHU Jie;YAO Zhi-Gang(College of Chemistry,Chemical Engineering and Materials Science,Soochow University,Suzhou 215123,China;Analysis and Testing Center,Soochow University,Suzhou 215123,China;School of Pharmacy,Hangzhou Normal University,Hangzhou 311121,China)

机构地区：[1]苏州大学材料与化学化工学部,苏州215123 [2]苏州大学分析测试中心,苏州215123 [3]杭州师范大学药学院,杭州311121

出　　处：《分析化学》2024年第6期866-875,共10页Chinese Journal of Analytical Chemistry

基　　金：江苏省大型科学仪器开放共享自主研究课题项目(No.TC2021A027)资助。

摘　　要：氨基酸表面活性剂(AAS)具有低毒性、抗菌性、温和性和抗腐蚀性等优良性能,近年来在日化、食品和医药等行业受到了广泛关注。研究表明,AAS分子级尺度的结构特点与其物理化学性质密切相关。本研究采用多种高分辨固体核磁共振(SSNMR)技术开展了固体状态下N-月桂酰基-L-丙氨酸(NLLA)氢键结构、局部动态学和分子组装结构的研究。通过2D^(1)H-^(1)H DQ-SQ和2D^(1)H-^(1)H DQ sideband pattern等技术并结合分子模拟,发现两个NLLA分子的羧基之间存在分子间氢键作用;结合^(13)C-^(1)H FSLG-HETCOR谱和13C T1的研究发现,相邻NLLA分子的酰胺基团之间存在氢键作用,继而推断NLLA分子通过分子间氢键作用形成具有反式和顺式两种构型的组装结构;此外,依据^(13)C{1H}CP/MAS谱化学位移信息,发现NLLA烷烃链端呈反式(trans)和旁式(gauche)两种构象,其中,trans构象表现为两个13C共振谱峰,分别对应于NLLA分子通过氢键作用所组装的两种构型结构;最后,依据SSNMR实验数据,绘制了NLLA分子在固体状态下的分子组装结构示意图。本研究为NLLA等AAS样品或同类型材料的分子间氢键作用、组装结构的表征提供了可选择的SSNMR实验技术方案,从而为相关材料的构效关系研究提供数据支持。Amino acid surfactants(AAS)have excellent properties such as low toxicity,antibacterial,mildness,and corrosion resistance.In recent years,they have been widely applied in the field of daily chemicals,food and pharmaceutical industry.It is pointed out that the structure at molecular level largely affects the physical and chemical properties of AAS materials.In this work,the structures of solid-state N-lauroyl-L-alanine(NLLA)including intermolecular interactions,molecular local dynamics and molecular assembly were investigated by a variety of solid-state nuclear magnetic resonance(SSNMR)techniques.Based on 2D^(1)H^(1)H double quantum-single quantum(2D^(1)H^(1)H DQ-SQ),1 H1 H DQ sideband pattern and molecular simulation,it was found that there was a stable intermolecular hydrogen bond formed between the carboxyl units of two NLLA molecules.Combined with the study of 2D frequency switched Lee—Goldberg heteronuclear correlation(2D^(13)C^(1)H FSLG-HETCOR)and^(13)C T1,another type of hydrogen bond was probed,which existed between amide units of neighboring molecules.In addition,the conformation of alkyl chain ends was investigated.According to 1D^(13)C{1 H}cross polarization/magic angle spinning(CP/MAS)and 2D^(13)C^(1)H FSLG-HETCOR spectra,it was revealed that the alkyl-chain ends had both gauche and trans conformations.Moreover,the trans conformation showed two distinct 13C chemical shifts,originated from two NLLA molecular assembly forms.Accordingly,two NLLA molecular assembly structures were suggested which were transoid form and cisoid form.This work provided a SSNMR investigation strategy for characterizing the molecular local structure and dynamics of AAS materials,which helped task of researching and developing materials with improved chemical and physical properties.

关 键 词：固体核磁共振 氨基酸表面活性剂 N-月桂酰基-L-丙氨酸 氢键 组装结构 

分 类 号：TQ423[化学工程] O657.2[理学—分析化学]