1 H - NMR ( 500 MHz , CDCl 3 , δ ) : 7 . 81 ( d , J = 1 . 5 Hz , 4 H ) , 7 . 72 - 7 . 70 ( m , 4 H ) , 7 . 54 - 7 . 52 ( m , 8 H ) , 7 . 43 ( t , J = 7 . 5 Hz , 8 H ) , 7 . 32 ( t , J = 7 . 5 Hz , 4 H ) , 7 . 29 - 7 . 06 ( m , 20 H ) , 6 . 86 - 6 . 83 ( m , 2 H ) , 6 . 61 - 6 . 58 ( m , 1 H ) , 6 . 56 - 6 . 52 ( m , 2 H )