Chiral Recognition of Binaphthyl Derivatives with L-Undecyl Leucine Surfactants in the Presence of Sodium and Lysine Counterions
Chiral Recognition of Binaphthyl Derivatives with L-Undecyl Leucine Surfactants in the Presence of Sodium and Lysine Counterions
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DOI：
10.4236/ajac.2021.125012
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发表时间：
2021-05
期刊：
影响因子：
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通讯作者：
Mauro Garcia;Amanda Risley;F. Billiot;E. Billiot;K. Morris
中科院分区：
文献类型：
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作者：
Mauro Garcia;Amanda Risley;F. Billiot;E. Billiot;K. Morris
本文研究了在以氨基酸为表面活性剂的十一酰亮氨酸（und-Leu）为手性固定相的毛细管电泳中，反离子对1，1 '-联萘-2，2'-二胺（BNA）和1，1 '-联萘-2，2'-磷酸氢二酯（BNP）对映体的手性识别的影响。比较了在不同pH条件下使用两种不同的反离子（钠离子和赖氨酸离子）对联萘衍生物手性识别的影响。通过毛细管电泳对BNA和BNP对映体进行分离，使用und-Leu作为手性识别介质，当使用赖氨酸反离子时，与使用钠作为反离子相比，在pH 7的毛细管电泳中显着提高了对映体分离度。更具体地，在45 mM的表面活性剂浓度下，在pH 7下，当与钠相比使用赖氨酸作为抗衡离子时，观察到手性选择性的显著增加。在毛细管电泳实验中，以赖氨酸为对照，BNA和BNP的对映体分离度分别提高了6倍和1.1倍。此外，BNA和BNP对映体的保留因子也增加了约3.5倍和4倍，分别在赖氨酸抗衡离子的存在下相比，使用钠抗衡离子。当毛细管电泳中的运行缓冲液的pH值增加到11时，分辨率和保留因子几乎相同时，比较钠和赖氨酸抗衡离子的影响。这表明赖氨酸的正净电荷在手性识别中的重要作用。本研究提供了洞察的潜在优势，使用阳离子，pH依赖性抗衡离子，如赖氨酸显着提高联萘衍生物的手性识别时，使用手性阴离子表面活性剂作为毛细管电泳中的假固定相。
This study investigates the effect of counterions on the chiral recognition of 1,1'-Binaphthyl-2,2'-diamine (BNA) and 1,1'-Binaphthyl-2,2'-diyl hydrogenphosphate (BNP) enantiomers when using an amino acid-based surfactant undecanoyl L-leucine (und-Leu) as the chiral pseudostationary phase in capillary electrophoresis. The effects of using two different counterions (sodium and lysine) on the chiral recognition of binaphthyl derivatives were compared at varying pH conditions. The enantiomeric separation of BNA and BNP enantiomers via capillary electrophoresis, using und-Leu as the chiral recognition medium, significantly improved the enantiomeric resolution in capillary electrophoresis at pH 7 when using Lysine counterions as compared to using sodium as the counterion. More specifically, at a surfactant concentration of 45 mM, at pH 7, a significant increase in chiral selectivity was observed when lysine was used as the counterion compared to sodium. The enantiomeric resolution of BNA and BNP increased by 6-fold and 1.1-fold, respectively, in capillary electrophoresis experiments when lysine was utilized as the counterion compared to using sodium. Furthermore, the retention factor of BNA and BNP enantiomers also increased approximately 3.5-fold and 4-fold, respectively, in the presence of lysine counterions as compared to using sodium counterions. When running buffer in capillary electrophoresis was increased to pH 11, the resolution and retention factors were nearly identical when comparing the effects of the sodium and lysine counterions. This signifies the important role of lysine’s positive net charge on chiral recognition. This study provides insight into the potential advantages of using cationic, pH-dependent counterions such as lysine to significantly improve the chiral recognition of binaphthyl derivatives when using chiral anionic surfactants as the pseudostationary phase in capillary electrophoresis.