How to define basic dyes

As a dye substance, in addition to a chromophore group, it also needs a auxochrome group that can ionize the compound. The auxochromic group is formed by acidic groups such as -OH-, SO3H, -COOH and basic groups such as -NH2, -NHCH3, and -N(CH3)2. Their existence makes the dye material ionize, enhances the polarity, promotes the interaction between the dye and the tissue, and produces the dyeing effect. The positively charged dyes in the auxochrome group are called basic dyes, and vice versa, acid dyes.

Basic dyes are generally insoluble in water and alcohol. Colorless anions and colored cations can be ionized. The cations of basic dyes are colored ions, and the colored ions can be firmly combined with negatively charged parts in the cell.

As a basic dye, it must have color; it must have affinity with the dyed tissue. The color of the basic dye and its affinity with the tissue are determined by the molecular structure of the dye itself. The chromophore group that produces the color and the auxochrome group that produces the affinity with the tissue jointly determine the dyeing properties of the dye.