What absorbs at 1259 cm⁻¹ in an FTIR spectrum?
A band near 1259 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 1259 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) | 9 | 9 | 1.0 |
| Methacrylate | 9 | 9 | 1.0 |
| Acetate | 9 | 9 | 1.0 |
| C-O single bond | 8 | 8 | 1.0 |
| Alkyl C-H | 5 | 3 | 1.0 |
| Ring structure | 3 | 3 | 1.0 |
| Aromatic ring | 3 | 3 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Silicon carbon | 2 | 2 | 1.0 |
| C c single bond | 2 | 2 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Lignin | 1 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| S eq o | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 0.7 |
| Hydrogen bond | 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 |
|---|---|---|---|
| chitosan | 1259, 1650, 1655 | Acetate, Methacrylate, C-O single bond | 2 |
| polystyrene | 1259, 1020, 1600 | 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 1259 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
-
S eq o confidence 1.0
“The author's thanks to Ministry of 1259cm-1 corresponds to S=O bonds.”
Artemisia 等 - 2019 - The Properties of Brown Marine Algae Sargassum tur DOI: 10.14499/indonesianjpharm30iss1pp43 -
Alkyl C-H confidence 1.0
“Results and discussion cm-1 Si\CH at 1259.4 due to CH symmetric stretching of 3, at 3”
Ferreira 等 - 2013 - Surface modification of poly(dimethylsiloxane) by DOI: 10.1016/j.surfcoat.2013.02.035 -
C c single bond confidence 1.0
“LLM confirmed rule peak-group candidate”
Preparation, Characterization and Antibacterial Evaluation of Soy Protein Isolate Biopolymeric Films Loaded with Nalidixic Acid DOI: 10.1007/s10924-020-01729-4 -
Acetate confidence 1.0
“Similarly, the peak positions cor1259 wt% 4HF polymer on the ionic conductivity of PEO-10 NH 2 responding to C¼O stretching, C-O-C stretching, and”
Influence of high and low dielectric constant plasticizers on the ion transport properties of PEO: NH4HF2 polymer electrolytes DOI: 10.1177/0954008319894043 -
Acetate confidence 1.0
“In genThe cm-1, 1412 and 1423 the C-O stretching of aromatic ring's ether eral, the exchange process between the new and exchangeable cm-1 at 1259 and, the vibrations of aromatic ring (C C) at 1531 cations did not exhibit significant differ”
Tabak 等 - 2011 - Structural analysis of naproxen-intercalated bento DOI: 10.1016/j.cej.2011.09.027 -
Amide confidence 1.0
“1317.31 1298.03 C-N stretching vibrations of amide III 1259.45 1256.60 1256.60”
Physicochemical Properties and Functional Characteristics of Ecologically Extracted Shrimp Chitosans with Different Organic Acids during Demineralization Step DOI: 10.3390/molecules27238285 -
Lignin confidence 1.0
“cm-1, (2) Bands at 1259 assigned to syringyl ring and C-O stretch in lignin and xylan as reported cm-1 (attributed to amide III) (Fig.”
Erukhimovitch 等 - 2010 - Direct identification of potato's fungal phyto-pat DOI: 10.3233/SPE-2010-0483 -
Alkyl C-H confidence 1.0
“The characteristic band at 1259 assigned to the CH 2Cl wagging was only present in the spectra of PSVBC-30 but absent in the other spectra [27].”
Anion Exchange Membranes Based on Imidazoline Quaternized Polystyrene Copolymers for Fuel Cell Applications DOI: 10.3390/membranes11110901
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