For the ACb-MB the band around 3420 cm1 was shifted to ca. 3440 cm1 and showed an increase of
intensity, this band can be attributed to the N–H stretching combined
with the O–H vibration mode. The band at 1569 cm1 was shifted to
ca. 1640 cm1 and can be attributed to N–H vibration coupled with
C–N stretching mode [40],