[{"from": "human", "value": "Describe this molecule. [C][S][=Branch1][C][=O][=Branch1][C][=O][C][C][N][C][=Branch1][C][=O][N][Branch1][Ring2][C][C][Cl][N][=O]"}, {"from": "gpt", "value": "The molecule is a chloroethylating nitrosourea that causes DNA cross-linking, inhibiting DNA replication. (NCI)"}]