Molecular structure of Indigotrisulfonic acid tripotassium salt (CAS NO.67627-18-3) is:

Product Name: Indigotrisulfonic acid tripotassium salt
CAS Registry Number: 67627-18-3
IUPAC Name: tripotassium(2Z)-3-oxo-2-(3-oxo-5-sulfonato-1H-indol-2-ylidene)-1H-indole-5,7-disulfonate
Molecular Weight: 616.72348 [g/mol]
Molecular Formula: C₁₆H₇K₃N₂O₁₁S₃
H-Bond Donor: 2
H-Bond Acceptor: 13 
Product Categories: Classes of Metal Compounds;K (Potassium) Compounds (excluding simple potassium salts);Typical Metal Compounds 
Canonical SMILES: C1=CC2=C(C=C1S(=O)(=O)[O-])C(=O)C(=C3C(=O)C4=CC(=CC(=C4N3)S(=O)(=O)[O-])S(=O)(=O)[O-])N2.[K+].[K+].[K+]
Isomeric SMILES: C1=CC2=C(C=C1S(=O)(=O)[O-])C(=O)/C(=C/3\C(=O)C4=CC(=CC(=C4N3)S(=O)(=O)[O-])S(=O)(=O)[O-])/N2.[K+].[K+].[K+]
InChI: InChI=1S/C16H10N2O11S3.3K/c19-15-8-3-6(30(21,22)23)1-2-10(8)17-13(15)14-16(20)9-4-7(31(24,
25)26)5-11(12(9)18-14)32(27,28)29;;;/h1-5,17-18H,(H,21,22,23)(H,24,25,26)(H,27,28,29);;;/q;3*+1/p-3/b14-13-;;;
InChIKey: XOSMXDUITYWYGR-JRYLAINFSA-K

Safty information about Indigotrisulfonic acid tripotassium salt (CAS NO.67627-18-3) is:
Safety Statements: 24/25-22 
S24/25:Avoid contact with skin and eyes. 
S22:Do not breathe dust.

 Indigotrisulfonic acid tripotassium salt , its cas register number is 67627-18-3. It also can be called 1H-Indole-5,7-disulfonic acid, 2-(1,3-dihydro-3-oxo-5-sulfo-2H-indol-2-ylidene)-2,3-dihydro-3-oxo-, tripotassium salt .It is a dark blue fine crystalline powder.