2,7-Naphthalenedisulfonic acid, 4-amino-6-4-4-(2,4-diaminophenyl)azophenylaminosulfonylphenylazo-5-hydroxy-3-(4-nitrophenyl)azo-, dilithium salt

4-Amino-6-[[4-[[[4-[(2,4-diaminophenyl)azo]phenyl]amino]sulfonyl]phenyl]azo]-5-hydroxy-3-[(4-nitrophenyl)azo]-2,7-naphthalenedisulfonic acid dilithium salt