[{"from": "human", "value": "Create a molecule that satisfies the conditions outlined in the description. The molecule is a Contrast Agent for Ultrasound Imaging. The mechanism of action of sulfur hexafluoride is as an Ultrasound Contrast Activity."}, {"from": "gpt", "value": "[F][S][Branch1][C][F][Branch1][C][F][Branch1][C][F][Branch1][C][F][F]"}]