1 H - NMR ( 400 MHz , CDCl 3 ) : δ = 8 . 94 ( d , 2 H ) , 7 . 70 ( t , 4 H ) , 7 . 60 ( t , 2 H ) , 7 . 42 ( t , 2 H ) , 7 . 38 ( d , 4 H ) , 7 . 26 ( m , 3 H ) , 6 . 76 ( d , 2 H ) , 6 . 14 ( d , 2 H ) .