[{"from": "human", "value": "Generate a molecule based on the given description. The molecule is a Contrast Agent for Ultrasound Imaging. The mechanism of action of perflexane is as an Ultrasound Contrast Activity."}, {"from": "gpt", "value": "[C][Branch2][Ring1][#Branch1][C][Branch1][S][C][Branch1][=Branch2][C][Branch1][C][F][Branch1][C][F][F][Branch1][C][F][F][Branch1][C][F][F][Branch1][S][C][Branch1][=Branch2][C][Branch1][C][F][Branch1][C][F][F][Branch1][C][F][F][Branch1][C][F][F]"}]