[{"from": "human", "value": "Describe this molecule. [C][C@H1][Branch1][#Branch2][O][C@H1][Branch1][Ring2][S][Ring1][Branch1][C][O][N][C][=C][Branch1][#Branch2][C][=Branch1][=Branch1][=N][C][Ring1][=Branch1][=O][N][F]"}, {"from": "gpt", "value": "The molecule is a synthetic fluoro derivative of thiacytidine with potent antiviral activity. Emtricitabine is phosphorylated to form emtricitabine 5'-triphosphate within the cell. This metabolite inhibits the activity of human immunodeficiency virus (HIV) reverse transcriptase both by competing with the natural substrate deoxycytidine 5'-triphosphate and by incorporation into viral DNA causing a termination of DNA chain elongation (due to the lack of the essential 3'-OH group)."}]