What absorbs at 1135 cm⁻¹ in an FTIR spectrum?
A band near 1135 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 1135 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 | 6 | 6 | 1.0 |
| Acetate | 6 | 6 | 1.0 |
| Methoxy (OCH3) | 5 | 5 | 1.0 |
| Methacrylate | 5 | 5 | 1.0 |
| Ester | 3 | 3 | 1.0 |
| Silicon-oxygen (Si-O) | 3 | 2 | 1.0 |
| Silicon (Si) | 3 | 2 | 1.0 |
| Ring structure | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Siloxane (Si-O-Si) | 2 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
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 1135 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
-
Aromatic ring confidence 1.0
“In the Raman spectrum of C�O MOF-5 (Figure 3a), a stretching of the carboxylate cm-1,75 group was observed at 1611 while in-plane bending vibrations of the benzene ring were obtained at 1433 and 1135 cm-1.”
Ionic Liquid Functionalized Metal–Organic Framework ([DEIm][PF6]@MOF-5): Synthesis, Characterization, and Catalytic Application in the Reduction of 4-Nitrophenol DOI: 10.1021/acsomega.2c05808 -
Alkyl C-H confidence 1.0
“1135cm-1 of the glucose unit, CH bending in cellulose I and cellulose , is reported to be absorption band centered at”
Croitoru 和 Patachia - 2016 - Long-Chain Alkylimidazolium Ionic Liquid Functiona DOI: 10.1155/2016/7432528 -
C-O single bond confidence 1.0
“cm-1, fingerprint region, approximately between 1500 and 800 the main characteristic C-O C-O-C are due to the vibration of glycosidic bonds and of the elongation in the glycm-1 cm-1, bands of carbohydrates are visible, in particular, peaks”
Foschi 等 - 2022 - Advanced Analytical Approach Based on Combination DOI: 10.3390/ph15060763 -
Alkyl C-H confidence 1.0
“strong adsorptions below 1400 cm-1 are the result of the formation of methyl ketones or aldehydes, while the bands at 1135 and 1030 cm-1 are associated with a mixture of aliphatic esters and ethers, and that at 1135 cm-1 is more specificall”
Influence of Ultraviolet Radiation Exposure Time on Styrene-Ethylene-Butadiene-Styrene (SEBS) Copolymer DOI: 10.3390/polym12040862 -
Acetate confidence 1.0
“The cm-1 stretching vibration of C-O generated the absorption peak at 1135 [39].”
Purification and Characterization of a Novel Calcium-Binding Heptapeptide from the Hydrolysate of Tilapia Bone with Its Osteogenic Activity DOI: 10.3390/foods11030468 -
Silicon (Si) confidence 1.0
“It is important to note that the peak shift and modification obtained at 1200 and 1135 cm-1 can be attributed to the stretching of the -Si-Ocellulose and -Si-O-Sibonds, which suggests the successful deposition of the coating layers.”
N-Containing Hybrid Composites Coatings for Enhanced Fire-Retardant Properties of Cotton Fabric Using One-Pot Sol–Gel Process DOI: 10.3390/polym15020258 -
Carbonyl (C=O) confidence 1.0
“The bands at 1700 cm-1 and 1135 cm-1 were due to the carbonyl group of ester present in PMMA polymer.”
Fabrication of Colored Polymeric Membrane Using Clay-Based Nano Pigments of Safranin O (SO) Dye DOI: 10.3390/membranes13070619 -
confidence 1.0
“explicit assignment”
Roy 等 - 2020 - Exploring the Inclusion Complex of a Drug (Umbelli DOI: 10.1021/acsomega.0c04716
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