Artificial power plant in the micro-mab

Plants receive and store light energy very effectively – in a way that researchers from Switzerland and Germany have been able to imitate artificially for the first time

Man, as proud as he is of his constructions visible even from space (often they are walls), nevertheless uses again and again astonishingly ineffective basic principles. For example, the controversial Three Gorges Dam impounds over 1000 square kilometers of water to generate a full 18 gigawatts of power. Energy, that is the basic principle, is obtained from the fact that the water is so unevenly distributed between the reservoir and the outflow.

Biological systems work in a similar but much more effective way, for example during and after photosynthesis. There, too, it is a matter of first capturing energy and using these means to accumulate something – only on a much smaller scale. Nature uses a suitable process to concentrate ions or protons on one side of a biological membrane – and when the energy stored in this way needs to be called up, it opens the floodgates.

Previous attempts to artificially construct such systems document (doi: 10.1126/science.1130124) the two Japanese authors Kazushi Kinbara and Takuzo Aida from the University of Tokyo in the current ie of the scientific journal Science.

Your conclusion: it is already quite successful in capturing light energy; however, when the floodgates are opened, much more of it is lost than plants permit. However, the researchers are not publishing their overview without reason: in the same ie, a group of researchers from the Universities of Geneva and Wurzburg present their own construction plans, which have now been successfully implemented (doi: 10.1126/science.1126524).

For the first time, Stefan Matile’s team has succeeded in mimicking more than just individual steps in what is a daily routine for plants. First, they store light energy in a clever way: their molecular construction transports charge carriers released during excitation by light into an electron store so quickly that they have no time to recombine. Once there, the electrons cause an accumulation of protons. Now comes the moment to open the floodgates: The scientists dock a special molecule onto their construction, which firstly stops photosynthesis and secondly opens an outflow channel for the protons.

Another exciting aspect of the research work is that the scientists are building and using supramolecular systems, which are not yet taught in chemistry classes, at least not today. These are molecules which, through a relatively weak interaction (such as the hydrogen bond, which ensures that not only water vapor exists on earth, and which connects the DNA strands), form a common system with entirely new properties. If the molecules involved are chosen correctly, a self-organization process takes place that makes intervention by the builder, as in China, unnecessary.

However, the invention from Geneva and Wurzburg unfortunately still has one small problem: the channel through which the dammed medium flows cannot yet be closed again. When all protons have been discharged, the reservoir is no longer replenished. But at least the effects of this are far more harmless than a breach in the Three Gorges Dam.

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