4H-1-benzopyran-4-one, 7-hydroxy-3-(4-hydroxy-3-nitrophenyl)- 7-hydroxy-3-(4-hydroxy-3-nitrophenyl)-4H-chromen-4-one InChI=1/C15H9NO6/c17-9-2-3-10-14(6-9)22-7-11(15(10)19)8-1-4-13(18)12(5-8)16(20)21/h1-7,17-18