The degree of twisting of natural helical structures, such as the DNA double-helix, plays an essential role in many important biological functions. Because of their twisted architecture, artificial helices can facilitate the separation and the synthesis of chiral compounds—asymmetric molecules that cannot be superimposed with their mirror image.
New, small spring-like polymer chains, or oligomers, from organic compounds called o-phenylenes have been created by Eisuke Ohta, Takanori Fukushima, Takuzo Aida and colleagues at RIKEN Advanced Science Institute in Wako . These oligomers consist of benzene rings that connect to each other at a sharp angle, leading to their helical structure. The team’s oligomers can change shape and become more rigid when subjected to an electrochemical signal (Fig. 1). They could soon serve as single-molecule machines for application in molecular computers.
Many researchers have investigated molecules that alter their features such as color, luminescence and mode of aggregation when exposed to external stimuli. However, the stimuli-induced change in rigidity demonstrated by the RIKEN team is unprecedented and may open the door to new types of molecular switches.
The researchers synthesized the o-phenylene oligomers using an iterative approach, which allowed them to gradually incorporate electrochemically sensitive units to the oligomer’s backbone.
Ohta explains that while trying to generate the longest o-phenylene oligomers ever synthesized, they noticed that the oligomers possessed highly condensed electron clouds and exhibited a significant reversible difference in rigidity upon removal of one electron during oxidation reactions.
The helical configuration easily causes cyclization—the formation of non-helical structures— which makes the synthesis and investigation of open oligomer chains difficult. The researchers overcame this hurdle by replacing hydrogen atoms positioned at the extremities of the oligomers with so-called ‘nitro functional groups’. Moreover, the octamer, which consists of eight o-phenylene units, was essential for extending the helices while preventing the cyclization, providing long oligomers of up to 48 o-phenylenes.
While purifying their products, the researchers discovered that the nitro-bearing octamer underwent a ‘chiral symmetry-breaking process’, which produced crystals that contained helices with either a left- or right-handed twist. Furthermore, the helices rapidly switched handedness in solution. However, during oxidation these structures contracted, which slowed the switching process between the two chiral states, enhancing their lifetime. These long-lived states resemble 0 and 1 in binary code, making them attractive for optical memory storage.
The researchers are currently examining the chemical and physical properties of these oligomers, which remain unexplored to date. “We want to unveil these properties now,” says Ohta.
The corresponding author for this highlight is based at the Functional Soft Matter Research Group, RIKEN Advanced Science Institute.
 Ohta, E., Sato, H., Ando, S., Kosaka, A., Fukushima, T., Hashizume, D., Yamasaki, M., Hasegawa, K., Muraoka, A., Ushiyama, H., Yamashita, K. & Aida, T. Redox-responsive molecular helices with highly condensed ð-clouds. Nature Chemistry 3, 68–73 (2011).
During HIV infection, antibody can block B cells from fighting pathogens
14.08.2018 | NIH/National Institute of Allergy and Infectious Diseases
First study on physical properties of giant cancer cells may inform new treatments
14.08.2018 | Brown University
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.
Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
14.08.2018 | Information Technology
14.08.2018 | Life Sciences
14.08.2018 | Life Sciences