Bacterial photosynthetic reaction center harvests more light thanks to tailored organic antenna

Oct 24, 2012
Bacterial photosynthetic reaction center harvests more light thanks to tailored organic antenna

Getting energy from sunlight: Plants have it down; humans have not quite got the knack for it. Hybrid systems made from natural and synthetic components could open new routes for harvesting solar energy. Italian researchers have now introduced an approach to this type of system. As described in the journal Angewandte Chemie, they have combined the photochemical core of a bacterial photosynthetic system with an organic dye that acts as an "antenna", significantly improving the capture of light.

In all organisms fuelled by photosynthesis, the functional organization of the photosynthetic apparatus is the same: pigment-protein complexes capture the like a radio catching and conduct it to a central photochemical core, the reaction center. Here the energy is converted to an electron-hole pair: a negatively charged electron is separated from its molecular core, leaving behind a positively charged "hole". This charge-separated state must be maintained long enough to be used. The organism uses this to drive its metabolism. In technological applications, may be used to drive a redox reaction like the splitting of water into hydrogen and oxygen.

Nature has optimal control over these steps. Synthetic systems that efficiently capture light and use the energy to achieve charge separation have also been developed; however the lifetime of the charge separation is barely in the millisecond range. This is not enough to allow the energy to be drawn off efficiently. An interesting approach to solving this problem is to make that combine a tailored synthetic antenna with a natural "light converter". Previously, synthetic antennas have been made from , nanoscopic structures made of semiconductors.

Instead, researchers led by Gianluca M. Farinola and Massimo Trotta have elected to use a tailored organic as their antenna. These have several advantages over inorganic structures: The molecular diversity of organic compounds allows for very fine tuning of the spectroscopic and electronic properties of the antenna. At the same time, the molecular form and flexibility can be controlled so that the antenna has practically no effect on the reaction center and its function, unlike quantum dots. An organic antenna can also be attached to nearly any desired location on the reaction center.

The Italian researchers combined their organic antenna with the extensively researched reaction center of the purple bacterium Rhodobacter sphaeroides R-26. They demonstrated that the antenna does not disrupt the function of the natural light converted; instead it improves its activity in a range of wavelengths not efficiently absorbed by the purely biological system.

Explore further: Team pioneers strategy for creating new materials

More information: Trotta, M. Enhancing the Light Harvesting Capability of a Photosynthetic Reaction Center by a Tailored Molecular Fluorophore. Angewandte Chemie International Edition 2012, 51, No. 44, 11019–11023. dx.doi.org/10.1002/anie.201203404

Related Stories

Lessons to be learned from nature in photosynthesis

Sep 23, 2011

Photosynthesis is one of nature's finest miracles. Through the photosynthetic process, green plants absorb sunlight in their leaves and convert the photonic energy into chemical energy that is stored as sugars ...

Bio-inspired nanoantennas for light emission

Jul 30, 2012

Just as radio antennas amplify the signals of our mobile phones and televisions, the same principle can apply to light. For the first time, researchers from CNRS and Aix Marseille Université have succeeded ...

Recommended for you

Team pioneers strategy for creating new materials

Aug 29, 2014

Making something new is never easy. Scientists constantly theorize about new materials, but when the material is manufactured it doesn't always work as expected. To create a new strategy for designing materials, ...

Plug n' Play protein crystals

Aug 29, 2014

Almost a hundred years ago in 1929 Linus Pauling presented the famous Pauling's Rules to describe the principles governing the structure of complex ionic crystals. These rules essentially describe how the ...

Breaking benzene

Aug 27, 2014

Aromatic compounds are found widely in natural resources such as petroleum and biomass, and breaking the carbon-carbon bonds in these compounds plays an important role in the production of fuels and valuable ...

User comments : 0