Molecular Structure of Direct Violet 51 (CAS NO.5489-77-0):

IUPAC Name: 7-anilino-3-[[4-(2,4-dimethyl-6-sulfophenyl)diazenyl-2-methoxy-5-methylphenyl]hydrazinylidene]-4-oxonaphthalene-2-sulfonic acid; sodium 
Empirical Formula: C₃₂H₂₉N₅O₈S₂
Molecular Weight: 675.7314
H bond acceptors: 13
H bond donors: 4
Freely Rotating Bonds: 9
Polar Surface Area: 173.36 Å²
Index of Refraction: 1.681
Molar Refractivity: 175.26 cm³
Molar Volume: 462.8 cm³
Surface Tension: 59 dyne/cm
Density: 1.45 g/cm³
InChI
InChI=1/C32H29N5O8S2.2Na/c1-18-12-20(3)30(28(13-18)46(39,40)41)36-34-25-17-27(45-4)26(14-19(25)2)35-37-31-29(47(42,43)44)16-21-15-23(10-11-24(21)32(31)38)33-22-8-6-5-7-9-22;;/h5-17,33,38H,1-4H3,(H,39,40,41)(H,42,43,44);;/q;2*+1/p-2/b36-34+,37-35+;;
Smiles
c1(S(=O)([O-])=O)c(\N=N\c2c(cc(\N=N\c3c(S(=O)(=O)[O-])cc(cc3C)C)c(c2)C)OC)c(O)c2c(c1)cc(Nc1ccccc1)cc2.[Na+].[Na+]

  Direct Violet 51 , with CAS number of 5489-77-0, can be called 2-Naphthalenesulfonicacid,3-[[4-[(2,4-dimethyl-6-sulfophenyl)azo]-2-methoxy-5-methylphenyl]azo]-4-hydroxy-7-(phenylamino)-,disodium salt (9CI) ; Amanil Fast Violet BL ; Azine Light Violet BB ; Benzanil Fast Violet 2BL ; Benzo ViscoseViolet BL ; Chloramine Brilliant Fast Violet 3B ; Diphenyl Brilliant Violet RC ; Fastusol Violet BB-CF ; Pontamine Fast Heliotrope B ; Pyrazol BrilliantFast Violet 3B .