¹H NMR (700 MHz, DMSO) δ 13.59 (s, 1H), 8.96 (t, J = 6.3 Hz, 2H), 8.17 (d, J = 8.1 Hz, 2H), 7.61 (d, J = 8.5 Hz, 2H), 7.40 (t, J = 7.3 Hz, 2H), 7.35 (d, J = 7.5 Hz, 4H), 7.31 (t, J = 7.6 Hz, 4H), 7.22 (q, J = 7.3 Hz, 4H).