InChI=1S/C21H20O13/c22-8-5-11(25)13(12(26)6-8)9(23)3-1-7-2-4-10(24)14(27)18(7)33-21-17(30)15(28)16(29)19(34-21)20(31)32/h1-6,15-17,19,21-22,24-30H,(H,31,32)/b3-1+