Host-Guest FAB Mass Spectrometry between Carbohydarates and Organic Cations

在FAB质谱中已经证明了对映体选择性主体-客体络合。在几种碳水化合物中，修饰的β-甘露呋喃糖苷1区分手性铵离子客体如1-（1-萘基）乙基铵离子以及手性冠醚2。相对峰强度（RPI）法已被开发用于评价此类非对映体络合物离子，其中将目标主体（M）-客体（A^+）络合物离子[I（M+A^+）]的峰强度与内标主体（R）-客体（A^+）离子[I（R+A^+）]的峰强度进行比较：RPI值= [I（M+A）^+/I（R+A）^+]。本发明的对映选择性的特征在于RPI比值[I（M+A_<（R）>）^+/I（R+A_<（S）>）^+]在1.2至1.6的范围内（1.0*0.1;非对映选择性）。所观察到的（R）-对映体客体的偏好与CPK模型检查和相关着色结果一致。与手性冠醚2，FABMS/RPI对映体之间存在密切的对应关系，严格相关的溶液相的缔合平衡的能量。的RPI方法的有用性也显示通过比较在溶液中的相关平衡常数（NMR滴定）。

Enantioselective host-guest complexation has been demonstrated in FAB mass spectrometry. Among several carbohydrates, a modified beta-mannofuranoside 1 differentiates a chiral ammonium ion guest such as the 1-(1-naphthyl)ethylammonium ion as well as a chiral crown ether 2. The relative peak intensity (RPI) method has been developed to the evaluation of such diastereomeric complex ions where the peak intensity of the target host (M) - guest (A^+) complex ion [I(M+A^+)] is compared to that of the internal standard host (R) - guest (A^+) one [I(R+A^+)]: the RPI value = [I(M+A)^+/I(R+A)^+]. The present enantioselectivity is characterized by the RPI ratio value [I(M+A_<(R)>)^+/I(R+A_<(S)>)^+] in the range of 1.2 to 1.6 (1.0*0.1; non-enantioselectivity). The observed preference of the (R)-enantiomer guest is compatible with CPK model examinations and related coloration results. With a chiral crown ether 2, a close correspondence exists between the FABMS/RPI enantioselection and that of strictly related solution phase energetics in association equilibria. The usefulness of the RPI method is also shown by comparison to the relevant equilibrium constants (NMR titration) in solution.