[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is an organic sodium salt resulting from the formal condensation of indigo carmine (acid form) with two equivalents of sodium hydroxide. It is an indicator at pH 11.5-14, changing from blue to yellow. It has a role as a food colouring, a histological dye and a two-colour indicator. It contains an indigo carmine(2-)."}, {"from": "gpt", "value": "[C][=C][C][=C][Branch1][=N][C][=C][Ring1][=Branch1][S][=Branch1][C][=O][=Branch1][C][=O][O-1][C][=Branch2][Ring1][P][=C][Branch1][Ring2][N][Ring1][O][C][=N][C][=C][Branch1][Branch1][C][Ring1][Branch1][=O][C][=C][Branch1][Branch1][C][=C][Ring1][Branch2][S][=Branch1][C][=O][=Branch1][C][=O][O-1][O].[Na+1].[Na+1]"}]