What absorbs at 1149 cm⁻¹ in an FTIR spectrum?
A band near 1149 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 1149 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 |
|---|---|---|---|
| C-O single bond | 16 | 15 | 1.0 |
| Methoxy (OCH3) | 15 | 14 | 1.0 |
| Methacrylate | 15 | 14 | 1.0 |
| Acetate | 15 | 14 | 1.0 |
| Alkyl C-H | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Amide | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Acetyl | 1 | 1 | 1.0 |
| Ester | 1 | 1 | 0.95 |
| Carbohydrate | 1 | 1 | 0.8 |
| Sulfate (SO4) | 1 | 0 | 0.8 |
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 | 1149, 1660, 2930 | Acetate, Methacrylate, C-O single bond | 1 |
| ZnO | 1149, 1400, 3430 | Acetate, Methacrylate, C-O single bond | 1 |
| polypyrrole | 1149, 1700, 400 | Methacrylate, Acetate | 1 |
| calcium phosphate | 1149, 1070, 600 | C-O single bond, Methoxy (OCH3), Methacrylate | 1 |
| PMMA | 1149, 1722, 1383 | Methacrylate, Acetate, Methoxy (OCH3) | 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 1149 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
-
Acetate confidence 1.0
“The broad absorption band at 1149 cm-1 corresponds to the n(C-O) groups.”
Bakan 等 - 2019 - Synthesis, characterization, toxicity and in vivo DOI: 10.1007/s10965-019-1901-7 -
Alkyl C-H confidence 1.0
“The discrete band at 2920 cm-1 refers to the C-H groups of carbonic cm-1 scaffold The band on the spectrum at 1149 is derived from the C-O type bonds present in chains of the monomers constituting the CG and GG.”
Development of Composite Scaffolds Based on Cerium Doped-Hydroxyapatite and Natural Gums—Biological and Mechanical Properties DOI: 10.3390/ma12152389 -
Acetate confidence 1.0
“Moreover, in the SML, spectrum peaks at 1149cm(cid:2)1 suggest the presence of a C-O-C stretch from an ester group, alike to the other two resists.”
Gangnaik 等 - 2015 - Correlation of lithographic performance of the ele DOI: 10.1116/1.4926387 -
Acetate confidence 1.0
“At 1149.37 the sharp band was observed which corresponded to the C-O stretching of acetyl group present on the back bone of PVA.”
Gopinath 等 - 2023 - Mechanical, structural and optical properties of p DOI: 10.15251/JOR.2023.191.23 -
C c single bond confidence 1.0
“cm-1 1149 are the responsible peaks of protonated nitrogen atoms in cm-1 refers to the C-C stretching vibration in the polypyrrole.”
Munot 等 - 2019 - Electrochemical Investigations on Semi-conducting DOI: 10.4152/pea.201901043 -
Water (H2O) confidence 1.0
“Increased salt concenwas observed that the predominant peak at about 3450 tration resulted in the decreased intensity of the peaks 1149 corresponds to the water absorbed by the complexes during”
Polu 等 - 2015 - Poly(ethylene oxide)-lithium difluoro(oxalato)bora DOI: 10.1007/s11581-015-1474-3 -
Acetate confidence 1.0
“linkages (C-O stretch vibration) at 1149 The spectrum of ES showed a broad band characteristic of cm-1, carbonyl groups (C=O) at 1727 characteristic bands of hydroxyl groups (C-H stretch vibration) at”
Akhgari 等 - 2013 - Indomethacin electrospun nanofibers for colonic dr DOI: 10.5681/apb.2013.014 -
Acetate confidence 1.0
“peaked at 1450 whereas a broad band which commences at 1149 indicating asymmetrical cm-1 cm-1 -C-O-Cstretching of the ring [40].”
Aziz 等 - 2019 - High Proton Conducting Polymer Blend Electrolytes DOI: 10.3390/biom9070267
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