1 H NMR ( 399 . 9 MHz , DMSO - d 6 ) δ 2 . 56 - 2 . 60 ( 4 H , m ) , 3 . 18 - 3 . 22 ( 4 H , m ) , 3 . 72 ( 2 H , s ) , 7 . 28 - 7 . 32 ( 1 H , m ) , 7 . 37 ( 1 H , t ) , 7 . 37 - 7 . 41 ( 1 H , m ) , 7 . 54 ( 1 H , s ) , 7 . 68 - 7 . 75 ( 2 H , m ) , 7 . 94 ( 1 H , d ) ; m / z = 430 [ M + H ] +.