InChI=1S/C18H14N2O6/c1-18(26)16-11-10(15(24)17(18)25)9-8(14(23)12(11)19-20-16)7-5(13(9)22)3-2-4-6(7)21/h2-4,15,17,21,23-26H,1H3,(H,19,20)/t15-,17+,18+/m1/s1