Substituent-induced coupling of the two lowest excited singlet states of 2-methoxy-derivatives of 4-(N,N-dimethylamino)- and 4-(N-methylamino)benzonitrileDedicated to Professor Dr Z. R. Grabowski and Professor Dr J. Wirz on the occasions of their 75th and 60th birthdays.

The title compounds both exhibit strong features of interaction of their two lowest excited states, but only one of them, the dimethylamino derivative, exhibits dual fluorescence. This is a direct indication that state interaction and dual fluorescence are not directly related.