InChI=1S/C13H10N2O6/c16-5-1-2-6-7(3-5)13(21)15(12(6)20)8-4-9(17)11(19)14-10(8)18/h1-3,8-9,16-17H,4H2,(H,14,18,19)/t8-,9?/m0/s1