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Class: Thiazin
Ionisation: Basic

Chemical structure of Thionin

Common Name: Thionin
Suggested Name: Thionin
Other Names:

Lauth’s violet

C.I. Number: 52000
C.I. Name:
Color: Blue violet
Solubility Aqueous: 0.25%
Solubility Ethanol: 0.25%
Absorption Maximum: 602.5 (Merck) 598-599 (Conn) 596 (Gurr)
Empirical Formula: C12H10N3SCl
Formula Weight: 263.7


Thionin is a strongly metachromatic dye, useful for the staining of acid mucopolysaccharides. It is also a common nuclear stain and can be used for the demonstration of Nissl substance in nerve cells of the CNS. Compare its formula to those of the other metachromatic thiazin dyes.

There is, apparently, another dye named thionin blue (CI 52025) which is very occasionally confused with thionin, but cannot be substituted for it.


  1. R. D. Lillie.
    Conn’s Biological Stains
    Williams & Wilkins, Baltimore, MD., U.S.A.
  2. Susan Budavari, Editor,
    The Merck Index, Ed. 12
    Merck & Co., Inc., Whitehouse Station, NJ, USA
  3. Edward Gurr, 1971
    Synthetic dyes in biology, medicine and chemistry
    Academic Press, London, England.
  4. Aldrich chemical catalogue, 1992
    Aldrich Chemical Company, Milwaukee, WI, USA.