![]() This is very important if we are ever going to understand how photosynthesis works and if we want to use this knowledge to build truly efficient photovoltaic devices. To know how much this microenvironment affects the visible color, we first need to know what the true color of chlorophyll is. ![]() It is this interaction with the surrounding microenvironment what fine-tunes chlorophylls to cover as much of the visible spectrum as possible. Photosynthetic chlorophyll pigments are not alone in the leaf cells they are usually in a protein pocket. They only differ in a substituent of the porphyrin ring. Molecular structures of chlorophyll a ( left) and b ( right). Furthermore, chlorophyll a and b only differ in a substituent of the porphyrin, for chlorophyll a it is a methyl group (-CH 3) and for chlorophyll b it is an aldehyde group (-CHO) in the C7 position, but it is sufficient to significantly alter the absorption spectrum of the molecule. A slight change of the molecular structure leads to a change of the optical behavior. a proton – and the color changes from bright green to the dull color of overcooked broccoli. If you boil a leaf in water, this magnesium ion gets replaced by a hydrogen ion – i.e. Since there are no other strong pigments present in leaves, that is the whole story.Ĭhlorophyll molecules have a ring shape at one end – called a porphyrin – with a magnesium ion in the center. However, none of them absorbs green, so the leaf looks green because that light is reflected to our eyes instead of being absorbed by the leaf. They both also absorb light of other wavelengths with less intensity. Chlorophyll b absorbs mostly blue and yellow light. © Wikimedia Commons / Daniele Pugliesi, M0ttyĬhlorophyll a absorbs violet and orange light the most.
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