[
  {
    "molid": "mol33657",
    "smiles": "O=[N+]([O-])C1=CC=C[N+]=C1S",
    "microspecies": [],
    "macro_pka_values": [
      {
        "pka_value": -2.49,
        "charge_state_pre": 2,
        "charge_state_post": 1,
        "data_source": "OCHEM"
      }
    ]
  }
]