Lai Zhisheng, Shen Minhui, Shen Yong, Ye Yu-Xin, Zhu Fang, Xu Jianqiao, Ouyang Gangfeng
MOE Key Laboratory of Bioinorganic and Synthetic Chemistry/KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University Guangzhou 510006 China
College of Chemistry, Center of Advanced Analysis and Gene Sequencing, Zhengzhou University Zhengzhou 450001 China.
RSC Adv. 2022 Oct 13;12(45):29137-29142. doi: 10.1039/d2ra05029c. eCollection 2022 Oct 11.
Hydrogen bond networks (HBNs) have piqued the interest of the scientific community due to their crucial roles in nature. However, HBNs that are isolated from complicated backgrounds for unraveling their characteristics are still scarce. Herein, we propose that HBNs exist in complex anions formed between α-cyclodextrin (α-CD) and four benzoic acids (RBAs) in the gas phase. The complex anions are facilely extracted from solutions the electrospray ionization technique, and subsequently activated through collision for the investigation of their transition dynamics. It is revealed that the generation of deprotonated α-CD and neutral RBAs is the unexpected dominant dissociation pathway for all the four complex anions, and the complex anions formed from more acidic RBAs exhibit higher stabilities. These dissociation results are successfully explained by the cooperative stretching dynamics of the proposed HBNs that are formed involving the intramolecular HBN of α-CD and the intermolecular hydrogen bonds (HBs) between α-CD and RBAs. Furthermore, the rarely observed low barrier HBs (LBHBs) are suggested to be present in the HBNs. It is believed that the present complex anions can serve as a facilely accessible and informative model for studying HBNs in the future.
氢键网络（HBNs）因其在自然界中的关键作用而引起了科学界的关注。然而，从复杂背景中分离出来以揭示其特性的HBNs仍然很少。在此，我们提出HBNs存在于气相中α-环糊精（α-CD）与四种苯甲酸（RBAs）形成的复合阴离子中。通过电喷雾电离技术从溶液中轻松提取复合阴离子，随后通过碰撞进行活化以研究其跃迁动力学。结果表明，去质子化的α-CD和中性RBAs的生成是所有四种复合阴离子出人意料的主要解离途径，由酸性更强的RBAs形成的复合阴离子表现出更高的稳定性。这些解离结果通过所提出的HBNs的协同拉伸动力学得到了成功解释，该动力学涉及α-CD的分子内HBN以及α-CD与RBAs之间的分子间氢键（HBs）。此外，有人认为在所提出的HBNs中存在很少被观察到的低势垒氢键（LBHBs）。据信，目前的复合阴离子可以作为未来研究HBNs的一个易于获取且信息丰富的模型。
