Excited-state proton transfer and excited-state de-hydrogen bonding of the push-pull styryl system

The excited-state reaction of push-pull styryl system was studied in this work. In the excited state, compounds of 2-StP-NMe2, 2-StQ-NMe2, 4-StQ-NMe2 and 4-StP-NMe2 possess a sufficiently large acidity change for the proton transfer process to occur. For compounds 2-StT-NMe2 and 2-StN-NMe2 the acidity change is too small to induce the proton transfer process. A new type of excited-state de-hydrogen bond (ESDHB) process was observed in this study. It is possible to explore the polarity and HB effect of solvent simultaneously by using the ESDHB mechanism.