What absorbs at 1255 cm⁻¹ in an FTIR spectrum?
A band near 1255 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 1255 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 |
|---|---|---|---|
| Methoxy (OCH3) | 11 | 9 | 1.0 |
| Methacrylate | 11 | 9 | 1.0 |
| C-O single bond | 11 | 9 | 1.0 |
| Acetate | 11 | 9 | 1.0 |
| Alkyl C-H | 5 | 5 | 1.0 |
| Silicon carbon | 4 | 4 | 1.0 |
| Amide | 4 | 4 | 1.0 |
| Hydroxyl (O-H) | 4 | 4 | 1.0 |
| N h | 4 | 3 | 1.0 |
| Siloxane (Si-O-Si) | 2 | 2 | 1.0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Phosphate (PO4) | 2 | 2 | 1.0 |
| S eq o | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Sulfate (SO4) | 2 | 2 | 0.9 |
| Silicon silicon | 1 | 1 | 1.0 |
| Borate | 1 | 1 | 1.0 |
| Acetyl | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Sulfonyl | 1 | 1 | 1.0 |
| Chlorine | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 0.9 |
| Oxygen heterocycle | 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 |
|---|---|---|---|
| PVC | 1255, 834, 1195 | Methoxy (OCH3), Methacrylate, Acetate | 1 |
| starch | 1255, 1650, 1540 | Methacrylate, Acetate, C-O single bond | 1 |
| silver nanoparticles | 1255, 1636, 1631 | Methacrylate, Acetate, C-O single bond | 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 1255 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
-
Alkyl C-H confidence 1.0
“OH group 1593 CH bending 1240 S=O stretching 1255”
Artemisia 等 - 2019 - The Properties of Brown Marine Algae Sargassum tur DOI: 10.14499/indonesianjpharm30iss1pp43 -
Alkyl C-H confidence 1.0
“The bands at 1255 cm-1 corresponded to the skeletal cm-1 and 1332 were ascribed to the C-H wagging and bending vibration [12].”
Understanding Hydrothermal Dechlorination of PVC by Focusing on the Operating Conditions and Hydrochar Characteristics DOI: 10.3390/app7030256 -
confidence 1.0
“cm-1 the aromatic compounds appears at 1410 The peak at 1255 assigned to cm-1 the N-H group from the amides and the band at 1073 is attributed to the C-”
Synthesis and Catalytic Evaluation of Silver Nanoparticles Synthesized with Aloysia triphylla Leaf Extract DOI: 10.1007/s10876-016-1062-3 -
Amide confidence 1.0
“Additionally, two cm-1 peaks at 1255 and 1250 indicate the presence of amide III absorptions, which are very weak in infrared bending44.”
Antimicrobial potential of a ponericin-like peptide isolated from Bombyx mori L. hemolymph in response to Pseudomonas aeruginosa infection DOI: 10.1038/s41598-022-19450-8 -
C c single bond confidence 1.0
“The same trend was observed in C-C-O the intensity ratio of the bands at 1255 and 1274 assigned to the stretching mode.”
Shin 等 - 2002 - Structural comparison of Langmuir-Blodgett and spi DOI: 10.1021/la020135d -
Hydroxyl (O-H) confidence 1.0
“In the binary mixture of amine N-H bending ), 1489 (Aromatic C=C), 1122 cm-1 cm-1 methyldopa and monohydrate lactose, the endothermic (C-N stretch), 1286 (R-Alkyl O-H deformation cm-1 peak of drug melting is again missing, indicating a kind”
Siahi 等 - 2018 - Analytical Investigation of the Possible Chemical DOI: 10.15171/apb.2018.074 -
Acetate confidence 1.0
“cm-1 cm-1 The appearance of the oxazine ring is demonstrated by the peak at 1254.84 and 1143.65 which assign to the asymmetric and symmetric stretching vibrations of C-O-C of the oxazine ring respectively [11].”
Tan 等 - 2018 - Synthesis and Characterization of Polybenzoxazine DOI: 10.1063/1.5066866 -
Sulfonyl confidence 1.0
“FTIR spectra of potato starch (1) and sodium salt of sulfated starch (2) In the FTIR spectra of sulfated starch, in contrast to the original starch, there is a highcm-1, intensity band at 1255 which belongs to asymmetric stretching vibratio”
Akman 等 - 2020 - Synthesis and characterization of starch sulfates DOI: 10.1016/j.carbpol.2012.07.075
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