InChI=1S/C21H18O9S/c1-21(2)9-8-13-15(29-21)6-4-11-10-14(20(23)28-18(11)13)12-5-7-16(27-3)19(17(12)22)30-31(24,25)26/h4-10,22H,1-3H3,(H,24,25,26)