InChI=1S/C21H20O13/c22-8-5-10(24)14(11(25)6-8)9(23)2-1-7-3-12(26)18(13(27)4-7)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)/b2-1+