Substituent Dependent Photoreactivity of Donor-acceptor Substituted Phenyl Ethenes

Fluorescence and photoisomerization studies on donor-acceptor substituted phenyl conjugated molecules [e.g. 2-[(1E)-2-(4-nitrophenyl)ethenyl]furan (trans-1) and 2-[(1E)-2-(4-aminophenyl)- ethenyl]furan (trans-2)] in solvents of varying polarity suggest that ethenylfuran trans-1, with strong electron acceptor, exhibits large solvatochromic red shifted fluorescence maximum, highly dipolar excited state, and photostability. On the other hand, ethenylfuran trans-2 with electron donor amino substituent, is photoreactive and undergoes trans-cis photoisomerization. These results suggest that, in such systems, highly dipolar excited state does not favor trans-cis photoisomerization.