Bridged dual fluorescence

Michler s ketone MK also shows a dual fluorescence in alcohols, and, in this case, the bridged model compound MKB is available which clearly demonstrates that (1) a blocking of the phenyl group rotations (around the C-C bonds) blocks the channel toward the TICT state, and (2) the... 

In many cases, bridged or pretwisted model compounds have established the validity of the TICT model. Instead of acceptor substituents, aza-substitution as in DMAPYR and DMAPYM can also lead to dual fluorescence. 

---