[{"from": "human", "value": "Design a molecule that meets the criteria outlined in the description. The molecule is the bromide salt form of methylnaltrexone, a methyl derivative of noroxymorphone with selective, peripherally-acting mu-opioid receptor antagonistic activity. Methylnaltrexone displaces opioids from peripheral opioid receptors in the gastrointestinal tract, the bladder, and the skin, thereby reversing the opioid-related peripheral side-effects, such as constipation, urinary retention, and pruritis, respectively. Unlike naltrexone and due to the presence of a positively charged nitrogen atom in methylnaltrexone, this agent does not cross the blood-brain barrier and does not affect the centrally-mediated analgesic effect of opioids."}, {"from": "gpt", "value": "[C][N+1][Branch2][Ring2][Branch2][C][C][C@][C@@H1][C][=Branch1][C][=O][C][C][C@][Ring1][#Branch1][Branch2][Ring1][#Branch1][C@H1][Ring1][O][C][C][=C][Ring1][O][C][=Branch1][=Branch2][=C][Branch1][Branch1][C][=C][Ring1][=Branch1][O][O][Ring1][S][O][C][C][C][C][Ring1][Ring1].[Br-1]"}]