What absorbs at 1451 cm⁻¹ in an FTIR spectrum?
A band near 1451 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 1451 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 |
|---|---|---|---|
| Alkyl C-H | 14 | 13 | 1.0 |
| Secondary amine | 7 | 7 | 1.0 |
| Amide | 7 | 7 | 1.0 |
| C n single bond | 5 | 5 | 1.0 |
| Carboxyl (COOH) | 4 | 4 | 1.0 |
| Alkene (C=C) | 3 | 3 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| N h | 3 | 3 | 1.0 |
| Methyl | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Amino acid | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Sulfur heterocycle | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Hydroxyl (O-H) | 1 | 1 | 1.0 |
| C#c | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 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 |
|---|---|---|---|
| silver nanoparticles | 1451, 1636, 1631 | Alkyl C-H, Amide | 1 |
| nanoparticles | 1451, 1732, 1647 | Alkyl C-H, Amide | 1 |
| silver nanoparticles (AgNPs) | 1451, 1100, 1749 | Amide, Alkyl C-H | 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 1451 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
-
Ring structure confidence 1.0
“An increase was observed in the absorbances of CN ring stretching vibration (1451 cm-1) by introducing pyrrole (Py) derivatives on P(AN-co-VAc) matrix.”
Cetiner 等 - 2011 - Characterization of Conductive Poly(Acrylonitrile- DOI: 10.1007/s12221-011-0151-z -
C#c confidence 1.0
“1450.86cm-1 1541.57, related to be alkynes (monosubstituted) group, σ alkanes group, carboxylic acid dimer, hydroxyl aryl ketones, nitro compounds, tertiary ammonium ions.”
Novel approach to synthesis silver nanoparticles using plant pathogenic fungi, Puccinia graminis DOI: 10.1016/j.matlet.2012.04.103 -
Alkene (C=C) confidence 1.0
“Peaks at 1646 cm-1 and 1451 cm-1 correspond to C=C stretch and C-C stretching respectively.”
Kumar 等 - 2021 - Centella asiatica mediated facile green synthesis DOI: 10.1016/j.inoche.2021.108865 -
Amide confidence 1.0
“cm-1), cm-1), cm-1), (1450.65 C-N stretching (1394.53 amide III or C-N stretching (1235.67 CO-O-C cm-1), cm-1) symmetric stretching vibration (1073.59 stretching vibration of C-O groups ( 928.78 and”
Encapsulation of olive leaf phenolics within electrosprayed whey protein nanoparticles; production and characterization DOI: 10.1016/j.foodhyd.2019.105572 -
Metal oxygen confidence 1.0
“Assigned to vibration mode of Ag-O.”
Suan 等 - 2017 - Effects of Ag2O nanoparticles addition on electric DOI: 10.1016/j.cjph.2017.08.012 -
Amide confidence 1.0
“1439 [25] 3 4-MeIm 1438 CH deformation and C-N stretching 1451”
Ye 等 - 2007 - Intermolecular hydrogen bonds formed between amino DOI: 10.1088/1674-0068/20/04/461-467 -
Sulfur heterocycle confidence 1.0
“Both spectra displayed A thiophene ring vibration was found at 1451 and =”
Ashraf 等 - 2014 - Preparation and properties of multilayered polymer DOI: 10.1515/polyeng-2013-0297 -
Alkyl C-H confidence 1.0
“The peaks at 1451 correspond to C-H stretching of the aromatic compounds (Figure 3).”
Bello 等 - 2020 - Phytobiological-facilitated Production of Silver N DOI: 10.4274/tjps.galenos.2019.10846
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