InChI=1S/C18H12O12S/c19-10-5-8(6-11(20)14(10)21)12-15(22)16(29-18(12)25)13(17(23)24)7-1-3-9(4-2-7)30-31(26,27)28/h1-6,19-22H,(H,23,24)(H,26,27,28)/b16-13-