In organic chemistry, chlorins are tetrapyrrole pigments that are partially hydrogenated porphyrins.

The term "chlorin" strictly speaking refers to only compounds with the same ring oxidation state as chlorophyll.

[5] Isobacteriochlorins are found in nature mostly as sirohydrochlorin, a biosynthetic intermediate of vitamin B12, produced without going through a chlorin.

In living organisms, both are ultimately derived from uroporphyrinogen III, a near-universal intermediate in tetrapyrrole biosynthesis.

[8] The B(III)subchlorins were directly synthesized as meso-ester B(III)subchlorin from meso-diester tripyrromethane, these class of compound showed very good fluorescence quantum yield and singlet oxygen producing efficiency[9][10]