In organic chemistry, a chlorin is a large heterocyclic aromatic ring consisting, at the core, of three pyrroles and one pyrroline coupled through four methine linkages. Unlike a porphyrin, a chlorin is therefore largely aromatic but not aromatic through the entire circumference of the ring.

Magnesium-containing chlorins are called chlorophylls, and are the central photosensitive pigment in chloroplasts. A related compound, with two reduced pyrroles, is called a bacteriochlorin.

Because of their photosensitivity, chlorins are in active use as photosensitizing agents in experimental laser cancer therapies.

See also

• Corrin

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