[{"from": "human", "value": "Describe this molecule. [C][C][Branch2][Ring2][C][C][C@H1][C][=C][Branch2][Ring1][=Branch1][C@H1][C@][Ring1][Branch1][Branch1][Ring2][C][Ring1][Branch2][C][=Branch1][C][=C][C][=Branch1][C][=O][O][C][Ring1][=Branch2][C][=Branch1][C][=O][O-1][C]"}, {"from": "gpt", "value": "The molecule is a monocarboxylic acid anion that is the conjugate base of pentalenolactone E, obtained by deprotonation of the carboxy group; major species at pH 7.3. It is a conjugate base of a pentalenolactone E."}]