Although plants have efficiently captured energy from sunlight for millions of years, producing light-harvesting and energy storage devices based on photosynthesis is no easy task.
Now, a research team led by Makoto Fujita from the University of Tokyo and Tahei Tahara from the RIKEN Advanced Science Institute has found a simple way to mimic the initial stage of photosynthesis by mechanically trapping a guest molecule inside a cage structure1.
Prototypical artificial photosynthetic systems contain donor- and acceptor-type molecules. When light is absorbed by the donor, it becomes photo-excited—its electrons move to higher energy states. The acceptor group can receive and store these energetic electrons, but only if the donor and acceptor come together into what is known as an exciplex, or an excited state complex.
The difficulty is bringing together the donor and acceptor groups. An exciplex can form only if the two components are close enough and in the proper orientation during photo-excitation.
Fujita and Tahara’s team ensured exciplex formation by locking a photoactive donor molecule called bisanthracene inside a molecular cage acceptor. The self-assembled cage is highly water soluble as it contains six charged palladium atoms. The cage panels, however, are organic molecules and form a hydrophobic (water-repelling) pocket inside the cage when dissolved in water.
According to Jeremy Klosterman, the lead author of the study, the donor molecule bisanthracene is not soluble in water and, at high temperatures, is driven into the hydrophobic cage pocket. Once the solution cools, the bisanthracene is too large to exit the cage and remains trapped inside.
“Synthetically, our system is incredibly straightforward,” says Klosterman. “Simply mixing the host cage and the guest bisanthracene in water and heating causes the exciplex to self-assemble.”
Ultrafast laser spectroscopy of the host–guest complex found that the excited bisanthracene donor transferred the majority of its energy, 82%, to the exciplex state. Klosterman says the effective energy transfer is due to the extremely tight fit and strong interactions between the mechanically linked host and guest.
“This study helped us resolve an important question,” states Klosterman. Typically fluorescent molecules are non-emissive upon encapsulation by cages, but now they can infer that energy transfer into the host–guest exciplex state decreases the fluorescence lifetime.
By choosing a guest molecule that does not form an exciplex, the researchers have developed a new water-soluble fluorescent dye with a long lifetime—ideal for applications including biological sensing and imaging.
1. Klosterman, J.K., Iwamura, M., Tahara, T. & Fujita. M. Energy transfer in a mechanically trapped exciplex. Journal of the American Chemical Society 131, 9478–9479 (2009).
The corresponding authors for this highlight are based at the RIKEN Molecular Spectroscopy Laboratory and the School of Engineering, University of Tokyo
Supersonic waves may help electronics beat the heat
18.05.2018 | DOE/Oak Ridge National Laboratory
Researchers control the properties of graphene transistors using pressure
17.05.2018 | Columbia University
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology