The State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, China.
J Mass Spectrom. 2011 Jun;46(6):535-45. doi: 10.1002/jms.1922.
More than 310 kinds of cluster ions of S(m) P(n) H(k) (k+) are observed in a single ESI mass spectrum of a mixed solution of serine and phosphoric acid. Some typical cluster ions are selected, activated by collision in a FT ICR cell, and the dissociation pathways were deduced in detail. For large singly protonated ions, the collisions cause the ejection of subunits of serine or phosphoric acid subsequently producing the ions of S(2) P(4) H(1) (1+) , which can be further dissociated by the loss of phosphoric acid molecules in turn and form the protonated serine dimer and monomer. However, for the doubly protonated ions, the dissociation pathways change from the loss of a protonated serine dimer for the ions of S(7) P(9) H(2) (2+) to the neutral loss of H(3) PO(4) for the ions of S(7) P(12) H(2) (2+) or the neutral loss of serine or H(3) PO(4) for the larger clusters, indicating the effect of cluster sizes on the process of dissociation. The structure of S(2) P(4) H(1) (1+) is suggested based on B3LYP/6-31G(d,p) calculations. The diversity and structural orderliness of the hetero-cluster ions are mainly attributed to the network of hydrogen bonds inside the cluster ions and the extraordinary amphotericity of the components.
在丝氨酸和磷酸混合溶液的单 ESI 质谱中观察到超过 310 种 S(m) P(n) H(k) (k+)簇离子。选择了一些典型的簇离子，在 FT ICR 细胞中通过碰撞进行激活，并详细推导了它们的解离途径。对于大的单质子化离子，碰撞导致丝氨酸或磷酸的亚单位相继被逐出，随后产生 S(2) P(4) H(1) (1+)离子，它可以通过依次失去磷酸分子进一步解离，并形成质子化丝氨酸二聚体和单体。然而，对于双质子化离子，解离途径从 S(7) P(9) H(2) (2+)离子的质子化丝氨酸二聚体的丢失转变为 S(7) P(12) H(2) (2+)离子的 H(3) PO(4)中性丢失，或者对于更大的簇，丝氨酸或 H(3) PO(4)的中性丢失，表明簇大小对解离过程的影响。基于 B3LYP/6-31G(d,p)计算，提出了 S(2) P(4) H(1) (1+)的结构。杂原子簇离子的多样性和结构有序性主要归因于簇离子内部氢键网络和组分的非凡两性。
