Figure Electron beam induced intermolecular Coulomb decay process of benzene dimer
Supported by the National Natural Science Foundation of China (approval number: 11974272, 11774281), the team of Professor Ren Xueguang from the School of Physics of Xi’an Jiaotong University and overseas researchers discovered for the first time the Coulomb decay phenomenon between organic biomolecules, in order to understand the structure and dynamics of biological macromolecules.
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The result is titled "Ultrafast energy transfer between π-stacked aromatic rings upon inner-valence ionization" and was published on December 20, 2021.
"Nature Chemistry" (Nature Chemistry) magazine
Article link: https://doi.
Intermolecular π-stacking interactions widely exist in biological macromolecular systems, and are key factors that affect and control protein folding, DNA double helix structure, molecular recognition and self-assembly, DNA-drug interactions and other physicochemical properties
Benzene dimer (C6H6) 2 is a prototype molecule for studying π-stacking, and has important basic research value in the fields of physics, chemistry, molecular biology and materials science
Recently, in the study of the ionization process of complex atomic and molecular systems (van der Waals clusters, hydrogen bond systems), it has been found that the de-excitation process of one of the molecules may trigger ultra-fast energy transfer between molecules (femtosecond time scale) and environment The further ionization of molecules is the intermolecular Coulombic decay (ICD)
Whether this novel physical phenomenon exists in the π-stacked complex molecular system is still unknown, and it is still a challenging scientific problem to fundamentally reveal the ICD process in the biological macromolecular system
The team of Professor Ren Xueguang of the School of Physics of Xi'an Jiaotong University and his collaborators used a multi-particle coincidence momentum imaging spectrometer (response spectrometer) combined with a supersonic biological cold target and pulsed photoelectron source technology to carry out electron beam and benzene dimer collision ionization experiments
Studies have shown that when biological tissues are exposed to ionizing radiation, more destructive chain reactions may occur than expected
In the study of benzene dimers, the inner shell ionization of the benzene molecule in the C2s state will trigger energy transfer between molecules, thereby ionizing the second benzene molecule and releasing a low-energy electron.
The two molecular ions are separated under the effect of Coulomb repulsion (Coulomb repulsion).
The experiment measured the electrons and ions emitted after the reaction, combined with first-principles calculations and molecular dynamics simulations, the system reduced the entire process of benzene dimer ionization and dissociation, and confirmed the existence of ultrafast in the π-stacked organic biomolecule system Intermolecular Coulomb decay phenomenon
This reaction directly destroys two adjacent biomolecules and eventually leads to bond breakage.
At the same time, low-energy electrons and molecular free radicals with biological toxicity are generated, which can irreversibly damage cells or DNA chains (Figure)
This research work has opened up a new way to analyze the structure and dynamics of biological macromolecules and reveal the mechanism of DNA radiation damage.
It will also provide effective guidance for the development of precision medical technology.
It is expected to promote the further expansion and development of atomic and molecular physics research into complex molecular systems.