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