Jun 30 2009
An international team of researchers has modified chlorophyll from an alga so that it resembles the extremely efficient light antennae of bacteria. The team was then able to determine the structure of these light antennae. This is the first step to converting sunlight into energy using an artificial leaf. The researchers will be publishing an article on their research findings in the online Early Edition of the PNAS journal in the week starting 29 June.Leiden研究人员Swapna Ganapathy在该研究的启动者Huub de Groot教授的监督下，基于该学科获得了博士学位。
Forests at nano scale
They are the subject of dreams: artificial forests at nano scale. Or pavements and motorways where gaps in the surface are filled with pigment molecules that collect sunlight and convert it into fuel and other forms of – clean – energy. But before this can happen, artificial photosynthesis systems first have to be developed that work both quickly and efficiently.
Two things are needed to generate fuel from sunlight: an antenna that harvests light, and a light-driven catalyst. The article in PNAS is about the first of these: the antenna.
Imitating light antennae of bacteria
The fastest light harvesters are to be found in nature: in green leaves, algae and bacteria. The light antennae of bacteria – chlorosomes – are the fastest of all. They have to be capable of harvesting minimal quantities of light particles in highly unfavourable light conditions, such as deep in the sea. These chlorosomes are made up of chlorophyll molecules. The art is to imitate these systems very precisely.
来自Huub de Groot的Würzburg大学的德国同事从藻类螺旋藻中修改了叶绿素，因此它们类似于细菌的颜料。然后，De Groot的Leiden组研究了这些半合成光天线的结构。
纳米技术
de Groot：'纳米技术和超分子系统变得越来越重要，但是很难确定它们的结构。经常制作所谓的漫画，以表明其结构可能是什么。
De Groot和他的同事成功地确定了其人工自组装的光天线的详细分子和超分子结构。他们使用固态NMR和X射线衍射的组合（请参阅附件）。X射线衍射使他们能够确定整体结构，而NMR使它们可以深入渗透到分子中。
Stacking of molecules
德·格鲁特（De Groot）：“我们已经知道细菌中的光触角形成了一种结构，就像树干的年度环一样。这些半合成触角中的分子似乎以不同的方式堆叠。他们是平坦的。但这也是我们提前想到的四种方式之一。
新的方法
The researchers still have to determine how the light antennae of modified Spirulina chlorophylls work in practice. De Groot: 'This is a completely new approach in this field.'
The new insights are coming in quick succession. Last month, De Groot, with an international team made up partly of different members, also reported a breakthrough in PNAS. In that article he showed how – also with a combination of NMR and another technique, namely electron microscopy – he had resolved the structure of the light antennae of the bacteria themselves. This allowed the researchers to explain how the antennae were able to function so quickly and so efficiently.
Zinc chlorins for artificial light-harvesting self-assemble into antiparallel stacks forming a microcrystalline solid-state material Swapna Ganapathy, Sanchita Sengupta, Piotr K. Wawrzyniak, Valerie Huber, Francesco Buda, Ute Baumeister, Frank Wurthner, and Huub J. M. de Groot PNAS online早期版本http://www.pnas.org/papbyrecent.shtml
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