Electronic Absorption Spectra of 2-Amino-3,5-Dichloro-2,6-Difluoro-Pyridine and 2-Hydroxy-5-Nitro Pyridine

Abstract

The near ultraviolet absorption spectra of 2-amino-3,5-dichloro-2,6-
difluoro pyridine and 2-hydroxy-5-nitropyridine in the vapour phase have
been recorded on Beckman DK-2A and a detailed vibronic analysis is
presented. They are found to exhibit one band system corresponding to
¹A_1g→  ¹B_1u (2100 Å) transition and two systems of bands arising from
  ¹A_1g→ ¹B_2u (2600 Å) and  ¹A_1g→ ¹B_1u (2100 Å). Transition of benzene
has been identified for 2-amino-3,5-dichloro-2,6-difluoropyridine and
2-hydroxy-5-nitropyridine. The spectra have been analysed assuming Cs
point group for each molecule. The assignments have been interpreted in
terms of ground and excited state fundamental frequencies to the probable
modes of vibration, The correlation to the IR fundamentals for both the
molecules and the red shift of 0, 0 bands have also been presented.