InChI=1S/C21H20O13/c22-9(2-1-7-3-12(25)15(27)13(26)4-7)14-10(23)5-8(6-11(14)24)33-21-18(30)16(28)17(29)19(34-21)20(31)32/h1-6,16-19,21,23-30H,(H,31,32)/b2-1+