Synthesis and evaluation of organic pigments. 3. Studies based on nonmutagenic twisted benzidines

Bis-chromophoric pigments prepared using nonmutagenic benzidine analogs wit h high dihedral angle across the biphenyl linkage are reported. The mutagen ic properties of twisted bisazomethine, disazoacetoacetanilide, disazopyraz olone, disazobenzimidazolone and disazonaphthol pigments were established u sing the standard Ames Salmonella mammalian mutagenicity assay and the Priv al modification. Results from these tests and from the evaluation of hue, c olor strength and photostability of the pigments prepared are reported. Som e of the new pigments are potential viable alternatives to those derived fr om 3,3'-dichlorobenzidine and other genotoxic analogs of benzidine. (C) 200 1 Elsevier Science Ltd. All rights reserved.