The complexation of alkali metal ions with amphiphilic fullerene derivatives has been investigated by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry. The formation of analyte ions occurs via two competing mechanisms including electron transfer from matrix-derived ions and metal ion attachment. The interplay of these processes has been examined by laser fluence dependent sample activation and by variation of the target composition. The attachment of metal ions has been established as the gentler and thus more efficient route towards the formation of intact analyte ions. Investigations into the metal ion complexation have been conducted to reveal the reactivity order of the alkali metals in these reactions and to elucidate the influence of structural differences of the analytes, as well as to unravel effects caused by the anionic counter ion of the metal. The experimental data have been derived by two complementary approaches. Competing reactants were either studied simultaneously, so that the product distribution would provide direct insight into the reactivity pattern, and/or product distributions were obtained in a large variety of separate experiments and normalized for reliable comparison. It has been found that the extent to which complexation is observed follows the charge density order of the alkali metal ions. The structural features of the fullerene-attached ligands were of profound influence on the attachment of the metal ion, inducing enhanced selectivity for the complexation with less reactive metals. The metal ion attachment is reduced with the use of smaller anionic counter ions. Rationalization of these findings is provided within the framework of the mechanisms of ion formation in MALDI.

中文翻译：

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通过基质辅助激光解吸/电离研究了碱性阳离子与衍生富勒烯的附着。

碱金属离子与两亲性富勒烯衍生物的络合物已通过基质辅助激光解吸/电离（MALDI）飞行时间（TOF）质谱进行了研究。分析物离子的形成通过两种竞争机制发生，包括从基质衍生离子的电子转移和金属离子附着。这些过程之间的相互作用已通过依赖激光注量的样品活化以及靶成分的变化进行了检验。金属离子的附着已被确定为形成完整分析物离子的更温和，更有效的途径。对金属离子络合进行了研究，以揭示这些反应中碱金属的反应顺序，并阐明分析物结构差异的影响，以及消除由金属的阴离子抗衡离子引起的影响。实验数据是通过两种互补的方法得出的。可以同时研究竞争性反应物，以使产物分布可以直接了解反应模式，和/或可以在各种单独的实验中获得产物分布并进行标准化以进行可靠的比较。已经发现观察到络合的程度遵循碱金属离子的电荷密度顺序。富勒烯连接的配体的结构特征对金属离子的连接具有深远的影响，从而提高了与反应性较低的金属络合的选择性。使用较小的阴离子抗衡离子可减少金属离子的附着。