What absorbs at 1325 cm⁻¹ in an FTIR spectrum?
A band near 1325 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 1325 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 | 5 | 5 | 1.0 |
| Alkyl C-H | 5 | 5 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| C-O single bond | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| C n single bond | 3 | 3 | 1.0 |
| C c single bond | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 2 | 1.0 |
| Lignin | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Nitrate | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 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 |
|---|---|---|---|
| montmorillonite | 1325, 1637, 523 | Methacrylate, Amide | 1 |
| polyaniline | 1325, 1565, 1570 | Amide, Alkyl C-H, Methacrylate | 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 1325 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
-
Nitrate confidence 1.0
“Note that a sharp band at 1325 cm-1, around 1325 signifying that 2,4-DP anion has associates with the nitrate stretching vibration.”
Bohari 等 - 2022 - Synthesis and Characterization of 2,4-Dichlorophen DOI: 10.22146/ijc.73546 -
confidence 1.0
“Raman band at 1325 is assigned to CN+· stretching vibration of nitrogen cation radical (forming due to protonation of PANI).”
Jin 等 - 2018 - Polymer anode used in hydrometallurgy Anodic beha DOI: 10.1016/j.hydromet.2018.01.020 -
C c single bond confidence 1.0
“1378m 1378m -OH bending, C-O-H bending, -OH bending, C-O-H bending, and C-H bending and C-H bending w w 1320w 1320w 1320w 1322w 1322w 1320w 1317 1317 C-c, and C-U skeletal vibration C-c, rrnd C-U skeletal vibration 1325 w 1325 w”
Liu 等 - 2006 - Characterization of the basidiomycetes Thelephora DOI: 10.1117/12.710905 -
Alkyl C-H confidence 1.0
“A peak at 1325 is due to -CH wagging.”
Synthesis, Structural, Optical, Electrical and Thermal Studies of Poly(vinyl alcohol)/CdO Nanocomposite Films DOI: 10.1007/s10904-017-0662-1 -
Amide confidence 1.0
“The vibration at 1325 and 1476 comes ∂2∼ E(cid:4) from the in-plane stretching of the C N bonds, the weak stretch1 m”
A comparative study on the experimental and calculated results of mid-infrared and Raman vibrational modes of nucleic acid bases DOI: 10.1016/j.jmgm.2017.04.016 -
Amide confidence 1.0
“1325.22 cm-1 assigned to C-N stretching of amine functional groups (Table 1).”
Facile Green Synthesis of Zinc Oxide Nanoparticles with Potential Synergistic Activity with Common Antifungal Agents against Multidrug-Resistant Candidal Strains DOI: 10.3390/cryst12060774 -
C c single bond confidence 1.0
“As mentioned earlier for the neat PEO, the absorption bands that correspond to correspond to the C-C bond are centered at 1350 and 1325 cm-1 for the gauche and trans conformation, cm-1 gauche trans the C-C bond are centered at 1350 and 1325”
Bollas 等 - 2017 - Polymer Conformation under Confinement DOI: 10.3390/polym9020073 -
Carbonyl (C=O) confidence 1.0
“tujafilina Figure 1 shows FTIR spectrum of with marked peaks corresponding to: cm-1), C-O stretching vibrations of glucose (1018 C-O and C-C stretching vibrations or C-Ocm-1), H, C-O-C deformation of carbohydrates (1172 CH3 deformation vibr”
Changes in Chemical Composition and Accumulation of Cryoprotectants as the Adaptation of Anholocyclic Aphid Cinara tujafilina to Overwintering DOI: 10.3390/ijms22020511
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