Reviewed by Lexie CornerDec 10 2024

Researchers at Hiroshima University's Graduate School of Advanced Science and Engineering have created an artificial polymer that self-organizes into a controlled helix, according to a study published in Angewandte Chemie on October 24th, 2024.

From the double-stranded helix of DNA to the spiraling band of heart muscle cells, helical shapes are observed in many aspects of biology.

Motivated by elegant biological helical structures, considerable effort has been devoted to developing artificial helical organizations with defined handedness for wide potential applications, including memory, sensing devices, chiral stationary phases, asymmetric catalysts, and spin filtering. The helical supramolecular polymer presented here is a new type of helical polymer.

Takeharu Haino, Study Corresponding Author and Professor, Graduate School of Advanced Science and Engineering, Hiroshima University

Polymers are a broad class of materials made up of large molecules. They occur naturally in substances like proteins and DNA, as well as in synthetic materials such as plastics. In supramolecular polymers, the molecules interact to form non-covalent bonds, which are directed in specific ways and result in various behaviors depending on their arrangement.

The polymer developed by the Hiroshima University team is a pseudo-polycatenane, which includes both mechanical and non-covalent bonds. Mechanical bonds can be broken under force without affecting the chemical structure of the non-covalent bonds, making them useful for designing materials that require precise control.

These polymers often feature helical structures that are "one-handed," meaning their twist only occurs in one direction. The direction of the twist influences how the polymer interacts with other materials. If researchers can control whether the twist is left- or right-handed, they can manipulate how the polymer reacts in certain conditions.

Haino added, "Helical polymers are potentially useful for various purposes; however, the synthesis of helical polymers with preferred handedness has remained challenging. Here, we present a novel synthetic method for helical polymers with preferred handedness via supramolecular polymerization controlled by complementary dimerization of the bisporphyrin cleft units."

Bisporphyrin cleft units are molecular components that can interact with one another to form molecular complexes, such as polymers. By carefully controlling the dimerization process, the researchers can predict the handedness of the resulting polymer.

"The proposed novel strategy for controlling the handedness of supramolecular helical pseudo-polycatenane polymers paves the way for the study of supramolecular polymer materials with functions directed by controlled helicity and mechanical bonding. Our goal is to apply these new helical supramolecular polymers to materials separation and catalysis -- or the acceleration of chemical reactions -- and to create a new functional chemistry of helical supramolecular polymers," Haino stated.

Co-authors from Hiroshima University's Graduate School of Advanced Science and Engineering include assistant professors Naoyuki Hisano, Takehiro Hirao, Shin-ichi Kihara, and Shin-ichi Tate, as well as graduate students Naoka Fujii, Kouta Tanabe, and Masaya Yoshida.

The Japanese Keirin Association and the Japan Society for the Promotion of Science both contributed to this study.

Journal Reference:

Fujii, N. et. al. (2024) Controlled Helical Organization in Supramolecular Polymers of Pseudo-Macrocyclic Tetrakisporphyrins. Angewandte Chemie. doi.org/10.1002/anie.202416770

Source:

Hiroshima University