¹H NMR (400 MHz, CDCl₃) δ 8.84 (s, 1H), 8.33 (d, J = 12.8 Hz, 2H), 7.80 (d, J = 7.5 Hz, 1H), 7.71 (t, J = 8.0, J = 7.6 Hz, 1H); ¹³C NMR (101 MHz, CDCl₃) δ 161.0 (s), 148.2 (s), 135.2 (s), 130.1 (s), 126.3 (s), 124.4 (s), 124.2 (s), 115.1 (s). HRMS (EI): calculated for C₉H₅N₃O₅: 235.0229; found: 235.0233.