InChI=1S/C18H14O12S/c19-9-3-1-7(2-4-9)12(17(23)24)15-16(30-31(26,27)28)13(18(25)29-15)8-5-10(20)14(22)11(21)6-8/h1-6,13,16,19-22H,(H,23,24)(H,26,27,28)/b15-12-