Abstract

The silver-mediated cytosine-guanine [CGAg]\(^{+}\) pair was characterized by mass-resolved IRMPD spectroscopy and electronic structure calculations at the DFT level. Three fragments were observed: [GAg]\(^{+}\), [CAg]\(^{+}\) and [CH]\(^{+}\). From the mass-resolved IRMPD spectra recorded on the mass of each fragment, two isomers of the [CGAg]\(^{+}\) complex were identified. The most populated isomer is a Hoogsteen structure [HooAg]\(^{+}\) between canonical cytosine (CKA(1)) and canonical guanine (GKA(9)), while the second isomer is an altered-Hoogsteen-like pair [*HooAg]\(^{+}\) in which guanine is in a non-canonical form (GKA(7)). The determined yields of each fragment are strongly dependent of the isomer of the precursor ion because of the fragmentation energy of the different channels. Finally, the [CH]\(^{+}\) is suggested to be produced by a metal-assisted proton transfer from guanine to cytosine preceded by an isomerization of the [HooAg]\(^{+}\) isomer.

Graphic Abstract

中文翻译：

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质谱解析IRMPD研究[胞嘧啶-鸟嘌呤] $$ \ hbox {Ag} ^ {+} $$ Ag +的气相结构和碎片化

摘要

银介导的胞嘧啶-鸟嘌呤[CGAg] \（^ {+} \）对通过质量分辨IRMPD光谱学和DFT级电子结构计算来表征。观察到三个片段：[GAg] \（^ {+} \），[CAg] \（^ {+} \）和[CH] \（^ {+} \）。从记录在每个片段质量上的质量分辨IRMPD光谱中，鉴定出[CGAg] \（^ {+} \）配合物的两个异构体。人口最多的异构体是经典胞嘧啶（CKA（1））和鸟嘌呤（GKA（9））之间的Hoogsteen结构[HooAg] \（^ {+} \），而第二个异构体是类似Hoogsteen的对[* HooAg] \（^ {+} \）其中鸟嘌呤为非规范形式（GKA（7））。由于不同通道的碎裂能量，每个碎片的确定产率在很大程度上取决于前体离子的异构体。最后，[CH] \（^ {+} \）被认为是由金属辅助的质子从鸟嘌呤转移到胞嘧啶而产生的，随后是[HooAg] \（^ {+} \）异构体的异构化。

图形摘要