Effects of hydrogen bonding on absorption and fluorescence spectra

Effects of hydrogen bonding on absorption and fluorescence spectra 

In the case of n — n transitions, it is often observed that the heteroatom of a heterocyle (e.g. N) is more basic in the excited state than in the ground state. The resulting excited molecule can thus be hydrogen bonded more strongly than the ground state, n - n fluorescence is thus more sensitive to hydrogen bonding than 

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