Fullerene-based compounds are being developed for an extensive range of biomedical applications, and may provide a completely new class of biologically useful reagents. In support of our continuing investigation and characterization of one such compound, e,e,e-fullerene(60)-63-tris malonic acid (1) we optimized the conditions for obtaining mass spectra. Both positive and negative ion mass spectra are obtained using electrospray ionization (ESI). However, the spectra are dramatically different in the different ionization modes. We studied the effect of solvent media, acid content as well as the concentration of the compound (1) on mass fragmentation pattern both in positive and negative mode. The best mass spectra were obtained when 1 was sprayed from a solution containing a weak organic acid added to aqueous methanol (1:1) in positive mode. We also analyzed the ion current as function of capillary voltage for selected ion. Fragment ions formed by the direct loss of carboxyl groups from the doubly-charged dimer occur for the loss of one, two and six carboxyl groups. Of these, the loss of one carboxyl is the most abundant. The dominant mechanism for the formation of singly-charged fragment ions arises from splitting of the doubly-charged dimers into singly-charged monomers with subsequent carboxyl losses.

中文翻译：

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生物活性立体异构体家族 e,e,e-(Methanofullerene(60-63)-Carboxylic Acids 的质谱研究

基于富勒烯的化合物正在开发用于广泛的生物医学应用，并且可能提供一类全新的生物有用的试剂。为了支持我们对一种此类化合物 e,e,e-富勒烯 (60)-63-tris 丙二酸 (1) 的持续研究和表征，我们优化了获得质谱的条件。使用电喷雾电离 (ESI) 获得正离子和负离子质谱。然而，在不同的电离模式下，光谱有很大的不同。我们在正负模式下研究了溶剂介质、酸含量以及化合物 (1) 的浓度对质量碎裂模式的影响。当 1 以正离子模式从添加到甲醇水溶液 (1:1) 中的弱有机酸溶液中喷洒 1 时，可获得最佳质谱图。我们还分析了离子电流作为所选离子的毛细管电压的函数。由双电荷二聚体中羧基的直接损失形成的碎片离子因失去一个、两个和六个羧基而发生。其中，一个羧基的损失最为严重。形成单电荷碎片离子的主要机制来自双电荷二聚体分裂成单电荷单体，随后羧基丢失。