What absorbs at 1571 cm⁻¹ in an FTIR spectrum?
A band near 1571 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 1571 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 |
|---|---|---|---|
| Carboxyl (COOH) | 6 | 5 | 1.0 |
| Amide | 5 | 5 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Oxygen heterocycle | 3 | 2 | 1.0 |
| Hydroxyl (O-H) | 3 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Protein beta sheet | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Thiol | 1 | 1 | 1.0 |
| Oxalate | 1 | 1 | 0.9 |
| Protein | 1 | 1 | 0.7 |
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 |
|---|---|---|---|
| graphene oxide | 1571, 1150, 3400 | Carboxyl (COOH) | 1 |
| protein | 1571, 1650, 1640 | Amide, N h, Carboxyl (COOH) | 1 |
| chitosan | 1571, 1650, 1655 | Amide, N h | 1 |
| oil | 1571, 1161, 1163 | Carboxyl (COOH), 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 1571 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
-
Carboxyl (COOH) confidence 1.0
“cm(cid:1)1 n(COO(cid:1) is associated with the ) antiThe band at 1571 symmetric stretching vibration.”
Dong 等 - 2020 - An indirect analytical approach based on ATR-FTIR DOI: 10.1039/d0ra03668d -
Thiol confidence 1.0
“CdC CdN cm-1(+)/2557 cm-1(-) A difference band at 2575 in H 2O Upon protonation of phycocyanobilin, a strong or cm-1 S-H is definitively assigned to a cysteine stretching mode, loses most of its intensity and would be band at 1571 showing a”
van Thor 等 - 2005 - Assignments of the Pfr-Pr FTIR difference spectrum DOI: 10.1021/jp052323t -
confidence 1.0
“1571cm-1 The major peak at shows the vibrations from oxygen-depleted carbon and lattice showing the fair reduction process during solvothermal conditions.”
Influence of Reduced Graphene Oxide on Effective Absorption Bandwidth Shift of Hybrid Absorbers DOI: 10.1371/journal.pone.0153544 -
confidence 1.0
“The peak at 1747 cm-1 was flavonoids and aromatic ring deformations), 1571 (N-H bending and C-N stretching in the amide”
Pleurotus Mushrooms Content in Glucans and Ergosterol Assessed by ATR-FTIR Spectroscopy and Multivariate Analysis DOI: 10.3390/foods9040535 -
Alkyl C-H confidence 1.0
“250 the out-of-plane bending C-H [3, 5, 7].The relative intensity metal (δ and/or δ N-Ag0) [8, 13] Cl-Ag0 1571cm-1 1488cm-1 of the band at and the band at indicates”
Benahmed 等 - 2018 - Spectroscopic Study of PolyanilineAgCl@Ag Nanocom DOI: 10.1155/2018/7320654 -
Carboxyl (COOH) confidence 1.0
“The Raman modes at merging with the IL peak at 1571 cm-1 ν 1467 and 1388 are assigned to the asymmetric as(COO)”
Dhumal 等 - 2016 - Molecular Interactions of a Cu-Based Metal-Organic DOI: 10.1021/acs.jpcc.5b10123 -
N-O bond confidence 1.0
“cm(cid:1)1, specic bands were found at 1571 and 631 indicating plate-like crystals.The HRTEM imageclearly showsthe existence nally that no hydroxyapatite appeared in the hardened prodconrming of a crystalline structure and that the sampl”
Decontamination of radioactive cesium ions using ordered mesoporous monetite DOI: 10.1039/c8ra02707b -
confidence 1.0
“at 1571 cm-1 in the LMWCs, the N-H bending mode of -NH2, was noticeably split at around 1638 3.3.”
Optimization and Characterization of Chitosan Enzymolysis by Pepsin DOI: 10.3390/bioengineering3030017
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a literature-backed analysis — in seconds.