1 H - NMR ( 400 MHz , DMSO - d 6 ) δ : 8 . 47 ( 2 H , d , J = 8 . 8 Hz ) , 8 . 32 ( 2 H , d , J = 8 . 8 Hz ) , 8 . 26 ( 2 H , d , J = 8 . 8 Hz ) , 7 . 71 ( 2 H , d , J = 8 . 4 Hz ) , 7 . 42 - 7 . 30 ( 5 H , m ) , 7 . 00 - 6 . 93 ( 4 H , m ) , 5 . 35 ( 2 H , s ) , 5 . 07 ( 2 H , s ) .