[{"from": "human", "value": "Based on the given information, design a molecule that meets the desired specifications. The molecule is an organophosphate oxoanion that is the conjugate base of ethyl dihydrogen phosphate arising from deprotonation of one of the OH groups of the phosphate. It has a role as an epitope and a phosphoantigen. It is a conjugate base of an ethyl dihydrogen phosphate. It is a conjugate acid of an ethyl phosphate(2-)."}, {"from": "gpt", "value": "[C][C][O][P][=Branch1][C][=O][Branch1][C][O][O-1]"}]