InChI=1S/C21H18O9S/c1-21(11-28-31(24,25)26)8-7-15-18(30-21)6-3-12-9-16(20(23)29-19(12)15)14-5-4-13(27-2)10-17(14)22/h3-10,22H,11H2,1-2H3,(H,24,25,26)