Scientists use light to change artificial chiral molecules for the first time

For the first time, American scientists have developed an artificial molecule that can change its chirality with a beam of light. This molecule can be used in terahertz technology including biomedical research, homeland security, and ultra-high-speed communication. Related research is published in "Nature" · Newsletter.

Chiral molecules are molecules that are mirror-symmetrical in structure in chemistry but cannot completely overlap. These molecules have very different left-handed or right-handed tendencies. It is the goal of scientists to observe the terahertz electromagnetic rays and even change the chirality of the molecules.

Zhang Xiang, the leader of the research and the Materials Science Division of Lawrence Berkeley National Laboratory, said: "We can change the chirality of natural materials, but the slow process will also change the structure of the materials. The chirality of the artificial molecules can be switched at the speed of light. "

The team of Zhang Xiang used a terahertz "metamaterial" made by processing nano-sized gold bars to create an exquisite artificial chiral molecule, which was then combined with a photoactive silicon medium and then used a bunch of external Light excites the "supramolecular" light, and as a result, the chiral changes in the form of circularly polarized terahertz light are observed. Moreover, this photo-induced excitation also allows scientists to dynamically control the chiral switching and circular polarization of terahertz light. Zhang Xiang said: "In the past, the use of photoelectric stimulation can only open or close the chirality of the 'supermaterial', but now, we can use the optical switch to change the chirality of this terahertz 'supermolecular'."

Zhang Xiang explained that the new "supramolecular" contains a three-dimensional superatom with opposite properties. They placed a silicon plate in different places within each super atom. In the end, the silicon plate broke the mirror symmetry and gave the supramolecular chirality. The silicon plate also assumes the function of a photoelectric switch that can change the supramolecular chirality under photoinduced excitation. He said: "Our system relies on the" marriage "of two superatoms with different chiralities. In a specific frequency range, one of the superatoms works and the other is not active. If the design is reasonable, the two superatoms Atoms will react inversely to the same external stimuli. Inactive superatoms will start to work, and the active superatoms will lose their activity, which changes the chirality of supramolecules. "

Terahertz electromagnetic rays, also known as T rays, are located in the frequency range of molecular vibrations, which makes them ideal non-invasive tools that can be used to analyze the chemical composition of organic and inorganic substances, change the chirality of supramolecular and control terahertz The circular polarization of light can be used to detect toxic and explosive chemicals, or in wireless communication and high-speed data processing systems. Because most biomolecules, including DNA, RNA and proteins, are chiral, new research can also benefit medical researchers and pharmaceutical professionals.

Another researcher, Antoinette Taylor, said that the design principle of their light-switching chiral terahertz supermolecules is not limited to changing chirality, but can also be used to dynamically change other electromagnetic properties.

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