What absorbs at 1558 cm⁻¹ in an FTIR spectrum?
A band near 1558 cm⁻¹ can point to several functional groups. Below are the most likely assignments, ranked by how much published evidence supports each — every one traceable to literature (DOI) and cross-validated against our 130,000+ reference spectra and knowledge graph.
Backed by 8 cited sources
Quick answer
A band near 1558 cm⁻¹ is usually interpreted by checking which functional groups repeatedly co-occur there in the literature, then confirming at least one or two additional peaks in the same sample. This page ranks those assignments by accumulated evidence rather than by a single fixed textbook rule.
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Amide | 14 | 13 | 1.0 |
| Aromatic ring | 9 | 9 | 1.0 |
| Ring structure | 9 | 8 | 1.0 |
| N h | 8 | 7 | 1.0 |
| Alkyl C-H | 6 | 6 | 1.0 |
| Secondary amine | 5 | 5 | 1.0 |
| C c single bond | 4 | 4 | 1.0 |
| Alkene (C=C) | 4 | 3 | 1.0 |
| Amine primary | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Oxygen heterocycle | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Chitosan | 1 | 1 | 1.0 |
| Boron nitrogen | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Protein beta sheet | 1 | 1 | 0.8 |
| N c o | 1 | 1 | 0.7 |
| Lignin | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| cellulose | 1558, 1735, 1650 | Amide | 1 |
| hemicellulose | 1558, 1730, 897 | Amide | 1 |
| chitosan | 1558, 1650, 1655 | Amide, N h | 1 |
| lignin | 1558, 1035, 1510 | Aromatic ring | 1 |
| starch | 1558, 1650, 1540 | Amide | 1 |
Materials are shown only when the same literature pool supports this band and at least one additional characteristic peak.
Spectrum logic
This band becomes meaningful only when read with its neighboring peaks. In practice, analysts first look at the assignments above, then check whether the same sample also shows other peaks expected for the same structural motif. A lone band near 1558 cm⁻¹ is usually not enough for material identification by itself.
Real-world usage
This type of query is common in polymer identification, unknown plastic screening, QC troubleshooting, recycled-material verification, and literature-backed peak assignment review.
Common mistakes
- Treating one isolated band as proof of a material without checking at least one or two supporting peaks.
- Ignoring overlap: multiple functional groups can contribute near the same wavenumber.
- Skipping validation when additives, blends, oxidation, or contamination may distort the spectrum.
Verification advice
When ambiguity remains, validate the hypothesis with DSC, GC-MS, or TGA, especially for blends, degraded samples, and filled polymers.
Literature behind these assignments
-
C c single bond confidence 1.0
“use cm-1 The peak at 1558 represents C C in quinoid ring and these bands indicate the personal potential conductivities of the materials.”
A facile synthesis of poly(aniline-co-o-bromoaniline) copolymer: Characterization and application as semiconducting material DOI: 10.1142/S0217979216500089 -
Aromatic ring confidence 1.0
“Most of CNFs had stretching stretching in conjugated aryl ketones and cm-1 vibrations of cellulose -OH, which were featured with broad C=C aromatic skeletal vibrations at peak 1558 [12,”
Nanostructural, Chemical, and Thermal Changes of Oil Palm Empty Fruit Bunch Cellulose Nanofibers Pretreated with Different Solvent Extractions DOI: 10.1007/s12649-017-0098-4 -
C=n confidence 1.0
“LLM confirmed rule peak-group candidate”
Structural and electrical behaviours of amino acid-based solid polymer electrolytes DOI: 10.1007/s12034-021-02464-9 -
C c single bond confidence 1.0
“cm-1 The peaks at 1558 show the bond C-C stretch (in-ring) as the functional group”
Enhanced Pharmaceutically Active Compounds Productivity from Streptomyces SUK 25: Optimization, Characterization, Mechanism and Techno-Economic Analysis DOI: 10.3390/molecules26092510 -
C c single bond confidence 1.0
“C=C C=C show show stretching stretching bonds bonds in in benzene benzene rings rings band band on on 1558 1558 cm The (C-O) (C cm-1.”
Alam 等 - 2017 - REMOVAL OF BASIC GREEN 5 BY CARBONACEOUS ADSORBENT DOI: 10.4314/bcse.v31i3.5 -
Protein confidence 1.0
“The major peaks in the loadings differing biopotential of cancer may be determined by different that could be used as a biomarker to indicate local aggressiveness protein structures corresponding to changes in the amide I peak in 1558cm(cid”
Baker 等 - 2008 - FTIR-based spectroscopic analysis in the identific DOI: 10.1038/sj.bjc.6604753 -
confidence 1.0
“but the bands at 1558 assigned to N-H The X-ray diffraction patterns characteristic for native potato cm-1, bending (amide II), and at 1382 assigned C-N stretchstarch and starch-based films with glycerol, chitosan, and ing (amide III) are n”
Novel Starch/Chitosan/Aloe Vera Composites as Promising Biopackaging Materials DOI: 10.1007/s10924-020-01661-7 -
Alkyl C-H confidence 1.0
“the bands characteristic of the vibration of the C=C bonds in the phenothiazine heterocycle amount of H-bonds was soft and flexible, while the 6X xerogel with the lowest amount was can be observed at 1598, 1573, and 1558 cm-1 and the band s”
TEGylated Phenothiazine-Imine-Chitosan Materials as a Promising Framework for Mercury Recovery DOI: 10.3390/gels8110692
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