1 H NMR ( 300 MHz , DMSO - d 6 ) δ 9 . 21 ( s , 1 H ) , 9 . 17 ( s , 1 H ) , 7 . 92 ( d , 2 H , J = 8 . 9 Hz ) , 7 . 66 ( m , 6 H ) , 3 . 13 ( t , 2 H , J = 7 . 3 Hz ) , 2 . 75 ( t , 2 H , J = 7 . 3 Hz ) , 2 . 38 ( m , 4 H ) , 1 . 45 ( m , 4 H ) , 1 . 36 ( m , 2 H ) ; MS ( m / z ) : 460 ( M ++ 1 ) .