[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is dianion of (2E)-2-(methoxycarbonylmethyl)but-2-enedioic acid arising from deprotonation of both carboxylic acid functions. It is a conjugate base of a (2E)-2-(methoxycarbonylmethyl)but-2-enedioic acid."}, {"from": "gpt", "value": "[C][O][C][=Branch1][C][=O][C][/C][=Branch1][#Branch1][=C][\\C][=Branch1][C][=O][O-1][/C][=Branch1][C][=O][O-1]"}]