[{"from": "human", "value": "Synthesize a molecule that matches the given characteristics. The molecule is major species at pH 7.3. It is an alpha,beta-unsaturated monocarboxylic acid, a methyl-branched fatty acid, a monoterpenoid and a polyunsaturated fatty acid anion."}, {"from": "gpt", "value": "[C][C][=Branch1][=C][=C][C][C][C][=Branch1][#Branch1][=C][C][=Branch1][C][=O][O-1][C][C]"}]