InChI=1S/C21H18N2O7/c22-9-11-1-5-13(6-2-11)18(14-7-3-12(10-23)4-8-14)29-21-17(26)15(24)16(25)19(30-21)20(27)28/h1-8,15-19,21,24-26H,(H,27,28)/t15-,16-,17+,19-,21?/m0/s1