InChI=1S/C21H18O9/c1-8-17(25)19(27)20(28)21(29-8)16-12(24)7-14-15(18(16)26)11(23)6-13(30-14)9-2-4-10(22)5-3-9/h2-8,19-22,24,26-28H,1H3/t8-,19+,20+,21?/m0/s1