Any of a group of dyes whose molecular structure involves a central carbon atom joined to three aromatic nuclei. CI numbers range from 42000 to 44999. The color is due in part to the aromatic rings and to the chromophore groups ═C═NH and ═C═N. The members of this class function as basic dyes for cotton, using tannin as a mordant, or if they contain sulfonic acid groups, as acid dyes for wool and silk. Examples are malachite green and methyl violet.See Triphenylmethane Dyes.