Wavenumber (cm−1)

Band assignments and remarks

3405.67 (vs, b)

O-H stretching (intermolecular H-bonded); N-H stretching (primary and secondary amines); N-H of pyrrole and imide groups (all these bands are probably overlapped into the big band observed between 3000 - 3674 cm−1)

2928.38 (s)

C-H stretching (-CH2- or -CH3)—two bands are expected; in this case, it’s overlapped with another band at ca. 2883.7 cm−1; O-H stretching of -COOH

~2510 (vw, b)

S-H stretching

2361.41 (w)

C≡N stretching

1732 (w)

C=O stretching of saturated carboxyl(ate)ic acid

1642.09 (s)

N-H bending; C=O stretching; O-H vibrations from glucoside units

1428.03 (m)

-C(=O)-O symmetric stretching

1372.1 (m)

O-H bending

1245.79 (vw)

C-O stretching

1154.19 (s)

C-OH stretching

1017.27 (vs)

C=S stretching; P-O-R stretching; (organo)phosphate stretching; inorganic tribasic phosphates, PO 4 3

858.17 (w)

Para-disubstituted benzene ring

763.67 (w)

Monosubstituted phenyl ring

721 (w)

-CH2- rocking; monosubstituted phenyl ring