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Innovative Double-Helical Monometallofoldamers Set to Transform Molecular Information Processing

Deoxyribonucleic acid (DNA), the molecule responsible for carrying genetic information in living organisms, operates through its structured helical form to transcribe and amplify data. This functionality has sparked significant interest among researchers seeking to create artificial molecular systems that can either replicate or exceed DNA’s capabilities. One promising area of innovation is the development of double-helical foldamers.

Foldamers represent a unique class of artificial molecules that adopt well-defined helical shapes, akin to those found in proteins and nucleic acids. Their ability to respond dynamically to stimuli, switch configurations, and exhibit chiral properties has made them a focal point for scientists exploring their potential as adaptable materials for various applications. The unique characteristics of double-helical foldamers provide even stronger chiral attributes and the fascinating ability to transfer chiral information between strands, creating opportunities for advancements in structural control in processes similar to nucleic acid replication.

Despite their potential, manipulating the chiral switching characteristics of these molecules poses complex challenges, particularly the need to harmonize the stability necessary for the molecule’s integrity with the dynamic nature required for controlled switching. Although numerous helical molecules have been developed over time, instances of reversing the twist direction in double-helix configurations and supramolecular systems have been limited.

A significant step forward has been achieved by a research team from Tokyo University of Science, led by Professor Hidetoshi Kawai from the Department of Chemistry. Along with Mr. Kotaro Matsumura, the team has devised a new mechanical motif known as double-helical monometallofoldamers that exhibit controllable chiral switching.

According to Professor Kawai, “In this research, we successfully synthesized a double-helical mononuclear complex that incorporates a single metal cation at the center of the helices. This arrangement effectively balances both stability and dynamic behavior. By adjusting the solvents, we can switch the twisting directions of both strands, allowing for inversion switching.”

This pivotal study was published in the Journal of the American Chemical Society on July 19, 2024.

The team developed the double-helical monometallofoldamers using bipyridine-type strands with L-shaped segments that, when combined with a zinc cation, form double-helical structures. Investigations utilizing X-ray crystallography confirmed the presence of a metal cation at the center of these structures.

The researchers meticulously examined the switchability of the synthesized monometallofoldamers in response to external stimuli. They found that the terminal parts of the double helices could unfold in solution, leading to an open configuration that is more favorable at elevated temperatures, while refolding occurs at lower temperatures, reverting to the double-helical form.

A particularly intriguing finding was that the helicity of the double-helical monometallofoldamer could be controlled by the use of achiral solvents. In non-polar solvents such as toluene and hexane, the structure adopts a left-handed twist (M-form), whereas in Lewis basic solvents like acetone and DMSO, it transforms into the right-handed (P-form). The configuration of chiral chains within the helical strands played a crucial role in this M/P switching process.

Furthermore, when a chiral strand was mixed with a strand devoid of chiral characteristics, the helical winding direction was transmitted and amplified to the achiral strand while maintaining the ability to reverse helicity.

Mr. Matsumura emphasized the importance of this new molecular entity, stating, “The synthesized double-helical monometallofoldamers hold the potential to revolutionize chiral switching materials, allowing for diverse chiral outputs from minute inputs. This technology could also lead to the creation of advanced chiral sensors.”

“Moreover, we anticipate that this innovative molecular framework can lead to the development of deracemized and organized supramolecular systems, reminiscent of natural structures, by leveraging their exceptional chiral properties.”

In conclusion, this groundbreaking research represents a vital advancement toward the realization of artificially controllable double-helical structures, setting the stage for the creation of sophisticated molecular systems and enhancements in molecular information processing.

More information: Kotaro Matsumura et al, M/P Helicity Switching and Chiral Amplification in Double-Helical Monometallofoldamers, Journal of the American Chemical Society (2024). DOI: 10.1021/jacs.4c06560

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phys.org