The fifth form of chlorophyll

摘要

Chlorophylls are essential for light-harvesting and energy transduction in photosynthesis. Four chemically distinct varieties (a-d) have been known for the past 60 years. Now, a primarily Australian-based team has isolated a fifth from stromatolites growing in Western Australia's Shark Bay (Chen M., Schliep M, Willows R.D., Cai, Z.-L., Neilan B.A., Scheer H. Science, 2010, 329, 1318-9). 'Chlorophyll f' possesses a formyl substituent at the 2-position (see figure), resulting in a red-shifting of absorption (706 nm) and fluorescence (722 nm) maxima compared to all other naturally occurring chlorophylls. The structural assignment was made by Drs Zheng-Li Cai and Min Chen, University of Sydney, and Dr Robert Willows, Macquarie University, on the basis of the pigment's optical, mass and nuclear magnetic resonance spectra, and density functional theory simulations. The work has received much media attention, being reported by Scientific American, New Scientist, Nature, Chemical and Engineering News, Discovery Magazine and green and bio-energy industries due to potential advantages the pigment may have in the production of biofuels and in solar cells.