What absorbs at 1241 cm⁻¹ in an FTIR spectrum?
A band near 1241 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 1241 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 | 11 | 11 | 1.0 |
| Methacrylate | 8 | 8 | 1.0 |
| Acetate | 8 | 8 | 1.0 |
| Alkyl C-H | 7 | 7 | 1.0 |
| Methoxy (OCH3) | 6 | 6 | 1.0 |
| C-O single bond | 5 | 5 | 1.0 |
| Phosphate (PO4) | 5 | 2 | 1.0 |
| Carboxyl (COOH) | 4 | 4 | 1.0 |
| Nucleic acid | 4 | 4 | 1.0 |
| Ester | 3 | 3 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| C n single bond | 3 | 3 | 1.0 |
| Phosphorus | 3 | 0 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| Protein alpha helix | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Phospholipid | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| N n bond | 1 | 1 | 1.0 |
| Acetyl | 1 | 1 | 1.0 |
| Ring structure | 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 |
|---|---|---|---|
| PVA | 1241, 1660, 2930 | Alkyl C-H, Acetate, Methacrylate | 2 |
| nanotubes | 1241, 1735, 1630 | Alkyl C-H, Methacrylate, Acetate | 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 1241 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
-
Amide confidence 1.0
“LLM confirmed rule peak-group candidate”
Modification of curcumin-loaded liposome with edible compounds to enhance ability of crossing blood brain barrier DOI: 10.1016/j.colsurfa.2020.124862 -
Acetate confidence 1.0
“1118 stretching 1241 stretching C-O C-O 1089 stretching 1157 stretching”
El Bialy 等 - 2020 - Comparative Toxicological Effects of Biologically DOI: 10.2147/IJN.S241922 -
Amide confidence 1.0
“Common cm-1 In these spectra, AH has much stronger peaks in 1241 and cm-1) (1643-1638 characteristic peaks of amide I and amide II 1072cm-1.”
Integral characterization of normal and alopecic hair at different degeneration stages by in-situ visible and chemical imaging DOI: 10.1016/j.saa.2020.118315 -
Ring structure confidence 1.0
“The appearance of cm-1 cm-1 the oxazine ring is indicated by the peak at 1241.03 and 1150.92 which attributed 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 -
Acetate confidence 1.0
“The C-O band of acetyl groups stretching cm-1 D vibrations is observed at different peaks from 1241”
Improvement of Optical Properties of Functionalized Polyvinyl Alcohol-Zinc Oxide Hybrid Nanocomposites for Wide UV Optoelectronic Applications DOI: 10.1007/s10904-023-02616-w -
Alkyl C-H confidence 1.0
“cm-1, discriminate three peaks (1328.80, 1373.5 and 1420.45) At interval (1050-1300) the cm-1 peaks (1024.02, 1046.54, 1087.13 and 1241.93) are noticed and referred to C-O stretching, cm-1 while IR peak at 1241.39 is expected to C-H wagging”
Abead 等 - 2023 - Study physical characteristics of Polyvinyl Alcoho DOI: 10.15764/pche.2014.02001. -
Amide confidence 1.0
“Microstructure Transmittance peak bands at 1647.36 (E2.0) to 1650.80 (E1.5) were the effects of carbonyl bond stretching of amide I, while bands 1240.51(E1.5)and1234.33cm(cid:3)1(E2.5)wereintheregionofamideIII.”
Alimi 等 - 2022 - Microstructural and physicochemical properties of DOI: 10.1016/j.heliyon.2022.e09148 -
N n bond confidence 1.0
“starching mode of the functional groups on the hybrid CNTs surface, originating from the hybridized cm-1 N-N CH-CH Obviously, peaks at 1392 and 1241 cm-1 might also be attributed to N-N and CH-CH3 bonds from carbon [40].”
Basheer 等 - 2020 - Synthesis, Characterization, and Analysis of Hybri DOI: 10.3390/polym12061305
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