Because of the formation of hydrogen bonds
with THBA, the 1597 cm
−1
band shifts to 1607 cm
−1
and the
993 cm
−1
band shifts to 1014 cm
−1
. The intensities of the
hydrogen-bonded bands (1607 and 1014 cm
−1
) are found to
increase with increasing xuntil 0.6. Atx> 0.8, the absorptions
of the hydrogen-bonded bands unusually diminish with
increasing x. This suggests a maximum complexation between
THBA molecules and the pyridine rings.