Peking University, March 5, 2018: Hydrogen bonding is a ubiquitous intermolecular interaction existing in nature, which plays a key role in chemical, physical and biological processes. Studying the hydrogen-bond dynamics mechanisms at single-molecule level, is an important issue for us to understand the nature of hydrogen bonding and even control/use it. In the future, we might artificially control the structure of water, DNAs and proteins, which will change the beings and the nature environment. However, the big challenge still exists. Recently, Professor Guo Xuefeng at Peking University in coloration with Professor Yang Jinlong at University of Science and Technology of China and Professor Zhong Yuwu at the Institute of Chemistry reported direct electrical measurements of hydrogen-bond dynamics at the single-molecule level on the basis of the platform of molecular nanocircuits.
Schematic representation of the device structure addressing direct electrical measurements of hydrogen-bond dynamics at the single-molecule level on the basis of the platform of molecular nanocircuits by building supramolecule-assembled single-molecule junctions.
In the past two years, Professor Guo’s Group and his collaborators have achieved a series of remarkable results in single-molecule chemical reaction dynamics and single-molecule biophysics. They developed the first fully reversible, two-mode, single-molecule electrical switch in the world (Science 2016, 352, 1443; J. Phys. Chem. Lett. 2017, 8, 2849); established the stereoelectronic effect of biphenyl on its electrical conductance at low temperature based on the platform of graphene-molecule single-molecule junctions in 2017 (Nano Lett. 2017, 17, 856); probed the dynamic behavior of a host-guest complex (Science Advances 2016, 2, e1601113); studied the reversible reaction process in the nucleophilic addition of NH2OH to a carbonyl group (Science Advances 2018, 4, eaar2177) and presented a reliable, label-free single-molecule approach to directly explore the dynamic process of basic chemical reactions. By using high-gain silicon nanowire-based field-effect single-molecule transistor circuits, they directly measured the single-molecule DNA hybridization dynamics (Angew. Chem. Int. Ed. 2016, 55, 9036) and adenosine triphosphatase hydrolysis dynamics (ACS Nano 2018, 11, 12789), demonstrating the ability of nanowire nanocircuits to directly probe the intrinsic dynamic processes of the biological activities with single-molecule/single-event sensitivity. On the basis of these systematic studies, they were invited to write reviews by Chem. Rev. and Chem in the field of single-molecule devices and demonstrated endless opportunities to elucidate the fundamental mechanisms underlying reactions and uncover important details of the most basic processes of life (Chem. Rev. 2016, 116, 4318；Chem 2017, 3, 373).
Recently they further applies this idea in studying the dynamic process of intermolecular interactions. A quadrupolar hydrogen-bonding system based on ureido pyrimidine-dione (UPy) with amino substituents is covalently incorporated into two graphene point contacts to build stable hydrogen-bond-bridged single-molecule junctions and realize the real-time observation of the hydrogen-bond dynamics. Intermolecular quadruple hydrogen bonding should behave as a good conducting channel, which is a prerequisite to realize long-term real-time monitoring of the hydrogen-bond dynamic behavior. The stochastic rearrangement of the hydrogen-bond structure changes the electron transport property of the junction, so the team could follow the hydrogen-bond dynamic process by monitoring the current signal from the device. On the basis of platform of the designed molecular nanocircuits, the team succeeds in directly observing the current fluctuations, including profuse information of hydrogen-bond dynamics with a strong solvent and temperature dependence. Both experimental and theoretical results consistently show the current fluctuations are stemmed from the stochastic rearrangement of the hydrogen-bond structure mainly through intermolecular proton transfer and lactam-lactim tautomerism.
Current-time curves of the hydrogen-bond device in diphenyl ether at different time scales and the corresponding kinetic analyses histogram.
This single-molecule electronic technique is a powerful approach to probe the fundamental molecular mechanisms of chemical reactions and biological activities that are not accessible in conventional ensemble experiments. On February 23, this work entitled “Direct observation of single-molecule hydrogen-bond dynamics with single-bond resolution” has been published on Nature Communications (Nature Communications 2018, 9, 807, DOI: 10.1038/s41467-018-03203-1).
Ph.D. student Zhou Ce from Professor Guo’s group, Dr. Li Xingxing from Professor Yang jinlong’s group and Dr. Gong zhongliang from Professor Zhong wuyu’s group are the co-first authors. Professors Guo Xuefeng, Yang Jinlong and Zhong wuyu are co-corresponding authors. This work received supports from National Natural Science Foundation of China, Ministry of Science and Technology of China and Chinese Academy of Sciences.
Source: College of Chemistry and Molecular Engineering
Edited by: Zhang Jiang
