Photo credit: www.sciencedaily.com

Breakthrough in Artificial Molecular Systems: Double-Helical Monometallofoldamers

Deoxyribonucleic acid, commonly known as DNA, serves as the fundamental molecular structure carrying the genetic blueprint of living organisms. With a sophisticated ability to transcribe and amplify information through its dual helical strands, scientists are keenly interested in creating artificial molecular systems that can replicate or exceed DNA’s functionalities. Among these endeavors, double-helical foldamers represent a promising avenue.

Helical foldamers are a type of synthetic molecule that naturally fold into distinct helical shapes, reminiscent of those found in proteins and nucleic acids. Their potential applications have sparked considerable interest, especially in fields requiring stimuli-responsive materials, chiral control, and cooperative supramolecular systems. Double-helical foldamers are particularly noted for their enhanced chiral properties and ability to transfer chiral information between strands. This capability could have substantial implications for higher-order structural manipulations akin to the functions of nucleic acids. Nevertheless, achieving effective control over the chiral properties of these systems remains a daunting challenge, primarily due to the need to balance the necessary dynamic switching with stability. While several helical molecules have been engineered previously, fewer studies have reported the ability to reverse the twist direction in such double-helix configurations.

In an exciting development, researchers at the Tokyo University of Science, Japan, led by Professor Hidetoshi Kawai from the Department of Chemistry, have introduced a novel mechanical motif called double-helical monometallofoldamers. Prof. Kawai elaborated on their work, stating, “We successfully synthesized a double-helical mononuclear complex that incorporates a single metal cation at the core of the helices, effectively balancing stability with dynamic responsiveness. By manipulating the winding directions of the helices in various solvents, we were able to achieve inversion switching.” Their findings were published in the Journal of the American Chemical Society on July 19, 2024.

The synthesis involved two bipyridine-type strands designed with L-shaped units that, when complexed with a zinc cation, formed the desired double-helical structures. X-ray crystallography confirmed these formations, clearly showcasing the position of the metal cation at the center. The research team explored the responsiveness of these monometallofoldamers to external stimuli, discovering that the terminals of the helices could unfold in solution temperatures, transitioning to an open form at high temperatures and refolding back into the double-helical shape at lower temperatures.

A particularly intriguing aspect of this study is the ability to control the helicity of the double-helical monometallofoldamer in response to achiral solvents. For instance, exposure to non-polar solvents like toluene and hexane results in a left-handed or M-form configuration, while interaction with Lewis basic solvents such as acetone and DMSO shifts it to a right-handed or P-form. The introduction of chiral chains into the helix strands plays a crucial role in facilitating this chiral switching. Notably, when a chiral helix strand interacts with an achiral counterpart, the winding direction and associated helicity can be transferred and amplified, preserving the ability to invert helicity.

Mr. Matsumura, also part of the research team, highlighted the broader implications of their discovery, stating, “Our developed double-helical monometallofoldamers present the opportunity for the creation of innovative switching chiral materials that can produce diverse chiral properties from minimal inputs. This work may also pave the way for the development of sophisticated chiral sensors. Furthermore, we anticipate that this unique molecular architecture could inspire the creation of organized and deracemized supramolecular systems, akin to those seen in biological entities through the transmission and amplification of their distinct chiral features.”

This groundbreaking study marks a crucial advancement in the pursuit of artificial, controllable double-helical structures, setting the stage for innovative high-order molecular systems and new frontiers in molecular information processing.

Source
www.sciencedaily.com