Complete Chlorophyll Structure And 9 Facts You should Know


Chlorophyll molecule and its structural facts, its types are explained in this article.

Chlorophyll is a green pigment present in the chloroplast of plant cell which has a prime role in photosynthesis. Plants are the primary producers of nature and they release oxygen as the byproduct of photosynthesis. Chlorophyll has a complex structure with a magnesium atom in its centre. In addition chlorophyll has found to be used in other fields.

9 facts –

  1. Chlorophyll is a green pigment present in plants, which is responsible for photosynthesis  an important process that takes place in plants.
  2. Chlorophyll is a good photoreceptor that absorbs sunlight and convert that to the energy needed for photosynthesis. Photosynthesis is the process through which plants makes their food with the usage of water and sunlight.
  3. Chlorophyll is located in plant’s chloroplast which are tiny structures in a plant cell.
  4. There are mainly 6 types of chlorophyll and in which 4 ones are found to be very important or most important.  They are chlorophyll a which is found in higher plants bacteria chlorophyll b which is found in green algae, and higher plants and chlorophyll c found in the diatoms, dinoflagellates and brown algae and the last one is chlorophyll d which is only found in red algae.
  5. Chlorophyll is a chelate molecule.
  6. Chlorophyll is also used as a dye. Natural green 3 or E140 is nothing it is chlorophyll.
  7. Chlorophyll is  used as a colouring agent in both cosmetics and food industries.
  8. Chlorophyll absorbs light energy in the visible region(700nm).
  9. Chlorophyll boost red blood cells, help with weight loss, heal damaged skin, neutralise top spin and prevent cancer.

Chlorophyll molecule

Chlorophyll is the green colouring matter of leaves and green stems. It is present in the chloroplast of the cell. Chlorophyll absorbs solar energy and through a series of redox reactions the overall endothermic process of combining water and carbon dioxide to form glucose and molecular oxygen, O2 is brought out.

    6CO2 + 6H2O → C6H12O  + 6O2

chlorophyll structure
chlorophyll wikimedia

Chlorophyll chemical structure


Chlorophyll is a complex of magnesium ion(Mg2+) with porphyrin. Magnesium ion (Mg2+)  is located in the centre of the porphyrin ring system and it is bonded to the  four nitrogen atoms present in the porphyrin ring. It is vital for the process, photosynthesis.

chlorophyll structure

Chlorophyll formula structure



The formula structure of chlorophyll is C₅₅H₇₂O₅N₄Mg.

Chlorophyll a structure

Chlorophyll a is a one form of chlorophyll pigment  that plays a crucial role in photosynthesis. This pigment makes the process possible through passing its energised electrons on to the molecules which will then manufacture sugars. Green sulphur bacteria contains small quantities of Chlorophyll a pigment.

The molecular structure of chlorophyll a consists of a porphyrin  ring, whose four nitrogen atoms are attached to a magnesium atom. Magnesium atom is attached in the centre of the ring system. It has other attached side chains and a hydrocarbon tail called phytol formed from phytol ester. The porphyrin  ring is a heterocyclic compound  derived by the condensation of pyrrole  molecules. The magnesium centre distinctively outline the structure of a chlorophyll molecule.

chlorophyll a

Chlorophyll b structure

It is the primary photosynthetic pigment which absorbs light energy. Due to the presence of a carbonyl group it is more soluble in polar solvents while the solubility of chlorophyll a in polar solvents is low.

The small difference in its one of the side chain enables it to absorb light radiations of different wave length.The formula of chlorophyll b is C55H70MgN4O6.

chlorophyll b

Chlorophyll c structure

Chlorophyll c is a type of pigment which is only found dinoflagellates. It is in blue green colour and  plays an important role in absorption of light in 447-52 nm wave length region. It also has a porphyrin ring, without an isoprenoid tail or a reduced ring like other chlorophyll pigments.

There are three types of chlorophyll c. They are chlorophyll c1, chlorophyll c2, chlorophyll c3. The formula of chlorophyll c1 is C35H30MgN4O5, chlorophyll c2 is C35H28MgN4O5, chlorophyll c3 is c36H28MgN4O7. The chlorophyll c1  has a ethyl group in its C8 group, chlorophyll c2  is the most common form of chlorophyll c and chlorophyll c3  is mainly found in micro algae.

chlorophyll c

Chlorophyll a vs b structure

  1. Chlorophyll a is a primary photosynthetic pigment while chlorophyll b is accessory pigment.
  2. Chlorophyll a is seen in all plants, algae, bacteria, cyanobacteria and phototrophs but chlorophyll b is seen in only in green algae and in plants.
  3. Chlorophyll a absorbs violet – blue and orange – red light from the spectrum but chlorophyll b absorbs only orange – red light from the spectrum.
  4. Chlorophyll a reflects blue – green colour but chlorophyll b reflects yellow – green colour.
  5. Chlorophyll a and chlorophyll b is soluble in petroleum ether  and methanol respectively.
  6. Rate of absorption is strong for chlorophyll a while weak for b.
  7. Chlorophyll a absorbs light radiations of wavelength range 430 nm to 660 nm while chlorophyll b absorbs 450 nm to 650 nm.
  8. Chlorophyll a has methyl, CH3 groups in its side chain but b has CHO, aldehydic group.
  9. The molecular weight of chlorophyll a and chlorophyll b is 839.51 g/mol and 907.49 g/mol respectively.
  10. Chlorophyll a has a methyl group in the third position of its porphyrin ring but Chlorophyll  b has aldehydic group in that position.

How does chlorophyll forms?

  • Conversion of amino acid called glutamic acid to 5 –aminolevulinicacid (ALA) is the first step of chlorophyll synthesis.
ALA synthesis
  • The two molecules of  aminolevulinic acid(ALA) are then condensed together to form porphobilinogen(PBG), which then forms the pyrolle ring in chlorophyll.
formation of PBG
  • In the next step four molecules of PBG associate together to form a porphyrin like structure. This phase comprises six enzymatic steps ending with the formation of product called protoporphyrin IX.
protoporphyrin IX formation
  • In the next step magnesium,Mg is inserted into the system with the help of enzyme called magnesium chelatase. After this the additional steps took place for the synthesis of chlorophyll.
chlorophyll formation
  • In the next phase the cyclisation of propionic acid side chains takes place to form protochlorophyllide. This process also consist of the reduction of one of the double bond existing in one of its ring using NADPH.
chlorophyll formation

Chlorophyll components

Chlorophyll has a protoporphyrin ring system, phytol tail end and Magnesium ion encased in the ring.

porphyrin ring

Conclusion

Chlorophyll is often called the blood of plants because it is remarkably similar molecular structure to our own blood. The pH value of chlorophyll is same as that of healthy blood.

Aparna Dev

Hi... I am Aparna Dev, a chemistry postgraduate with a good understanding of chemistry concepts. I am working in Kerala Minerals and Metals Limited Kollam with experience in the development of electrocatalysts as a part of post graduate thesis. Let's connect through LinkedIn-https://www.linkedin.com/in/aparna-dev-76a8751b9

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