[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is an organic anion obtained by removal of one of the methylene protons from barbituric acid. It is the major microspecies at pH 7.3 (according to Marvin v 6.2.0.). It is a conjugate base of a barbituric acid."}, {"from": "gpt", "value": "[C][=C][Branch1][O][N][C][=Branch1][C][=O][N][C][Ring1][#Branch1][=O][O-1]"}]