MECHANISMS OF DEACTIVATION OF THE LOW-LYING ELECTRONIC STATES OF 2,2'-BIPYRIDINE

The photophysical properties of 2,2′-bipyridine have been investigated in different solvents by means of lifetime measurements on the picosecond scale, quantum yield temperature dependence, and CS-INDO CI calculations. Both experimental and theoretical results indicate that in inert solvents the very low fluorescence quantum yield of this molecule is due to a very effective intersystem crossing to a local triplet state. The picture emerging from these data helps to gain insight into the elusive photophysical behavior of this compound. © 1990 American Chemical Society.