O=C1C(O)=C([N+](=O)[O-])C(=O)C([N+](=O)[O-])=C1O    mol31239    0_1
O=C1C([O-])=C([N+](=O)[O-])C(=O)C([N+](=O)[O-])=C1O    mol31239    -1_1