InChI=1S/C18H16N2O3/c1-12(14-5-3-2-4-6-14)20-18(23)15(11-19)9-13-7-8-16(21)17(22)10-13/h2-10,12,21-22H,1H3,(H,20,23)/b15-9+/t12-/m1/s1