Diketopyrrolo-pyrrole pigment

All polycyclic pigments, with the exception of triphenylmethyl derivatives, comprise anellated aromatic and/or heteroaromatic moieties. In commercial pigments, these may range from systems such as diketopyrrolo-pyrrol derivatives, which feature two five-membered heteroaromatic fused rings (DPP pigments) to such eight-membered ring systems as flavanthrone or pyranthrone. The phthalo-cyanine skeleton with its polycylic metal complex is somewhat unique in this respect. 

In the early eighties, Ciba-Geigy discovered a new type of heterocyclic pigments, based on a symmetric chromophor, the 1,4-diketopyrrolo(3,4c)pyrrole system (141) (R = alkyl, aryl, Cl, Br, CF3) ... 

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