InChI=1S/C19H18O11S/c1-28-19(24)17(10-12-3-6-14(21)16(9-12)30-31(25,26)27)29-18(23)7-4-11-2-5-13(20)15(22)8-11/h2-9,17,20-22H,10H2,1H3,(H,25,26,27)/b7-4+