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, |
858.17 (w) | Para-disubstituted benzene ring |
763.67 (w) | Monosubstituted phenyl ring |
721 (w) | -CH2- rocking; monosubstituted phenyl ring |