尼古丁-扁桃酸盐晶的制备及晶体结构分析

Preparation and Crystal Structure Analysis of Nicotine Mandelate Crystals

以制备尼古丁有机酸盐复合物并提供一种无烟气烟草制品中尼古丁新的添加形式为主要目的,利用超声加热搅拌方法合成了尼古丁-扁桃酸复合物,并在溶剂挥发条件下获得了尼古丁-扁桃酸盐晶单晶体。X射线单晶衍射结果显示:尼古丁-扁桃酸盐晶体为正交晶系,P212121空间群,晶胞参数a=0.950 74 nm,b=1.272 46 nm,c=2.04101 nm,α=90°,β=90°,γ=90°,Z=4。应用CrystalExplorer软件进一步解析其晶体结构,晶体中分子堆积方式表明,尼古丁离子与扁桃酸根离子两两紧密结合且整体形成菱形网格状结构,每个菱形格中都插入一个中性扁桃酸分子。“赫希菲尔德”表面分析显示,尼古丁-扁桃酸盐晶体中形成N2-H2···O5,O6-H6A···O5,O8-H8···N1这3种氢键使得分子在该处电子密度更加密集,在基于标准距离函数的“赫希菲尔德”表面上表现为红色圆点。2D指纹图谱说明,H原子在尼古丁-扁桃酸晶体中的分子间相互作用中起着至关重要的作用。相互作用能分析表明:尼古丁-扁桃酸盐晶体结构中存在21种不同类型的分子间相互作用能。由于N2-H2···O5,O6-H6A···O5,O8-H8···N1氢键的存在,尼古丁离子与邻近扁桃酸离子和扁桃酸分子间的相互作用能数值最大。采用能量框架模型实现了晶体结构中相互作用能的可视化,加深了对尼古丁-扁桃酸晶体结构中分子间相互作用能的深刻理解。本研究对探究尼古丁化学结合形态以及在无烟气烟草制品配方设计中具有一定的理论指导和应用价值。

Main purpose of this study was to prepare nicotine organic salt complex and provide a new nicotine addition form in smokeless tobacco products.Nicotine-mandelic acid complexes were synthesized by ultrasonic heating and stirring,and nicotine-mandelic acid crystals were obtained.Nicotine-mandelic acid crystal structure solved by SXRD belongs to orthonormal crystal system with space group P212121,the cell parameters are a=0.95074 nm,b=1.27246 nm,c=2.04101 nm,α=90°,β=90°,γ=90°,Z=4.In the crystal structure of nicotine-mandelic acid,nicotine ion and mandelic acid ion bind tightly and form a diamond grid structure,a neutral mandelic acid molecule is inserted into each diamond lattice.According to Hirshfeld surface analysis,the hydrogen bonds of N2-H2···O5,O6-H6A···O5,O8-H8···N1 make the electron density of molecules at that point is more intensive,which leads bright red areas on Hirshfeld surfaces mapped with dnorm.2-D fingerprints show that H plays an important role in the intermolecular interaction of nicotine-mandelic acid crystals.The result of interaction energy analysis is that 21 kinds of intermolecular interaction energies exist in nicotine-mandelic acid crystal structure.Because of the existence of N2-H2···O5,O6-H6A···O5,O8-H8···N1 hydrogen bonds,the interaction between nicotine ions and neighbouring mandelic acid ions or mandelic acid molecules can be significantly greater than others.Energyframe model was used for visualizing the interaction energy in the nicotine-mandelic acid crystal structure which can be applied to understand the interaction energy more conveniently and clearly.this results have important theoretical guidance and application value for exploring the chemical binding form of nicotine and formulation design of smokeless tobacco products.