InChI=1S/C21H20O12/c22-6-15-17(28)18(29)19(30)21(33-15)32-14-5-9-10(24)3-8(23)4-13(9)31-20(14)7-1-11(25)16(27)12(26)2-7/h1-5,15,17-19,21-22,28-30H,6H2,(H4-,23,24,25,26,27)/p+1