InChI=1S/C18H16O11S/c19-12-4-1-11(7-13(12)20)9-16(18(23)24)28-14-5-2-10(3-6-17(21)22)8-15(14)29-30(25,26)27/h1-8,16,19-20H,9H2,(H,21,22)(H,23,24)(H,25,26,27)/b6-3+