[{"from": "human", "value": "Synthesize a molecule that matches the given characteristics. The molecule is a radiopharmaceutical containing the radioisotope I-123 with diagnostic property. After absorption, the iodide is distributed through the extracellular fluid of the body and accumulates in the thyroid gland, thereby allowing measurement of thyroid function."}, {"from": "gpt", "value": "[Na+1].[123I-1]"}]