1 H NMR ( 499 . 8 MHz , DMSO - d 6 ) δ 2 . 48 ( 4 H , t ) , 3 . 09 ( 4 H , t ) , 3 . 45 ( 2 H , s ) , 3 . 60 ( 4 H , t ) , 3 . 74 ( 4 H , t ) , 6 . 91 ( 2 H , d ) , 7 . 18 ( 2 H , d ) , 7 . 58 ( 1 H , d ) , 8 . 24 ( 1 H , d ) ; m / z = 448 [ M + H ] +.