Chlorin

Chlorin

Names
Other names 2,3-Dihydroporphine
Identifiers
CAS Number	2683-84-3
3D model (Jmol)	Interactive image
ChEBI	CHEBI:36303
ChemSpider	58616
PubChem	65106
InChI InChI=1S/C20H16N4/c1-2-14-10-16-5-6-18(23-16)12-20-8-7-19(24-20)11-17-4-3-15(22-17)9-13(1)21-14/h1-6,9-12,22-23H,7-8H2/b13-9-,14-10-,15-9-,16-10-,17-11-,18-12-,19-11-,20-12- Key: UGADAJMDJZPKQX-CEVVSZFKSA-N InChI=1/C20H16N4/c1-2-14-10-16-5-6-18(23-16)12-20-8-7-19(24-20)11-17-4-3-15(22-17)9-13(1)21-14/h1-6,9-12,22-23H,7-8H2/b13-9-,14-10-,15-9-,16-10-,17-11-,18-12-,19-11-,20-12- Key: UGADAJMDJZPKQX-CEVVSZFKBJ
SMILES C(N1)(/C=C2N=C(C=C\2)/C=C3N/C(C=C\3)=C\4)=CC=C1/C=C5CCC4=N/5
Properties
Chemical formula	C20H16N4
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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Infobox references

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

• Corrin
• Photodynamic therapy

References

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.