(3E)-3-{[4-({4-[(E)-{2,4-diamino-5-methyl-3-[(E)-{4-[(E)-(4-sulfophenyl)diazenyl]phenyl}diazenyl]phenyl}diazenyl]phenyl}sulfanyl)phenyl]hydrazono}-6-oxocyclohexa-1,4-diene-1-carboxylic acid