1 H NMR ( 499 . 8 MHz , DMSO - d 6 ) δ 2 . 56 ( 4 H , t ) , 3 . 62 ( 2 H , s ) , 3 . 64 ( 4 H , t ) , 7 . 34 - 7 . 37 ( 1 H , m ) , 7 . 47 ( 2 H , d ) , 7 . 60 ( 1 H , d ) , 7 . 87 - 7 . 91 ( 1 H , m ) , 7 . 96 ( 1 H , d ) , 8 . 07 ( 2 H , d ) , 8 . 25 ( 1 H , d ) , 8 . 67 - 8 . 68 ( 1 H , m ) ; m / z = 440 [ M + H ] +.