T. Ganguly et al., N HETEROATOMIC EFFECT ON THE PHOTOPHYSICS OF A POLYPHENYL SYSTEM - 2,2'-DIPYRIDYLAMINE, Journal of photochemistry and photobiology. A, Chemistry, 94(2-3), 1996, pp. 113-118
A detailed investigation of the absorption and emission characteristic
s of 2,2'-dipyridylamine (DPyA) and diphenylamine (DPA) has been carri
ed out in different polar and non-polar solvents at room temperature (
300 K) and at 77 K. A dramatic change in both the characteristics has
been observed in DPyA in comparison with DPA. Measured fluorescence an
d phosphorescence lifetimes and critical study of the absorption and e
mission spectral data suggest that DPyA is more planar than DPA and it
s lowest-energy singlet state is of (1)L(a), type containing a little
charge transfer character. Evidence of the presence of a (1)n pi stat
e has been found in DPyA on protonation in the binary mixture of water
and sulphuric acid at room temperature.