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Not to be confused with chlorine.
Other names
2683-84-3 YesY
ChemSpider 58616 YesY
Jmol interactive 3D Image
PubChem 65106
Molar mass 312.36784
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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In organic chemistry, a chlorin is a large heterocyclic aromatic ring consisting, at the core, of three pyrroles and one pyrroline coupled through four =CH- linkages. Unlike porphin, the central aromatic ring structure of porphyrins, a chlorin is therefore largely aromatic but not aromatic through the entire circumference of the ring.[1]

Magnesium-containing chlorins are called chlorophylls, and are the central photosensitive pigment in chloroplasts.

Related compounds, with two pyrroles and two pyrrolines (which are like pyrroles with one double bond reduced to a single bond) in the macrocycle are called bacteriochlorins and isobacteriochlorins.[2]

Structures comparing porphin, chlorin, bacteriochlorin, and isobacteriochlorin. Note relocation of C=C double bond between the two bacteriochlorin isomers. There are two π electrons (symbolized by π e) for every double bond in the macrocycle.

Because of their photosensitivity, chlorins are in active use as photosensitizing agents in experimental photodynamic therapy.[3]

See also[edit]


  1. ^ Juse´lius, Jonas; Sundholm, Dage (2000). "The aromatic pathways of porphins, chlorins and bacteriochlorins". Physical Chemistry Chemical Physics 2 (10): 2145–2151. doi:10.1039/b000260g. 
  2. ^ "ChEBI". June 16, 2009. pp. isobacteriochlorin (CHEBI:52583). Retrieved 1 February 2012. 
  3. ^ Spikes, John D. (July 1990). "New trends in photobiology". Journal of Photochemistry and Photobiology B: Biology 6 (3): 259–274. doi:10.1016/1011-1344(90)85096-F.