What absorbs at 1176 cm⁻¹ in an FTIR spectrum?
A band near 1176 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 1176 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 |
|---|---|---|---|
| Alkyl C-H | 7 | 6 | 1.0 |
| C-O single bond | 6 | 5 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| Methacrylate | 4 | 4 | 1.0 |
| Acetate | 4 | 4 | 1.0 |
| Hydroxyl (O-H) | 3 | 3 | 1.0 |
| Ring structure | 3 | 3 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Amide | 2 | 2 | 1.0 |
| Aromatic ring | 2 | 2 | 1.0 |
| Metal hydroxyl | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| Quinone | 1 | 1 | 1.0 |
| Carbonyl (C=O) | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Nitrogen heterocycle | 1 | 1 | 1.0 |
| Fluorine (C-F) | 1 | 1 | 1.0 |
| C c single bond | 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 |
|---|---|---|---|
| GO | 1176, 1720, 1182 | Methacrylate, C-O single bond, 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 1176 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
“spectra of the PDPA in doped state, these being peaked at 1176, 1201, 1368, 1541 and 1603 These Raman lines were attributed to vibrational modes of C-H bending in benzene ring, C-N stretching, semi-quinoid”
Baibarac 等 - 2019 - Adsorption of 1,4-phenylene diisothiocyanate onto DOI: 10.1038/s41598-019-48314-x -
Acetate confidence 1.0
“(-) C-C ovb 1193 1205 ov 1188 1187 1178 skeletal vibration (+) 1176 C-O + C-C 1135 unclear 1135 unclear 1134 1134 1136 stretching stretching C-O”
Maeda - 2001 - IR spectroscopic study on the hydration and the ph DOI: 10.1021/la001346q -
Acetate confidence 1.0
“The peaks at 1176 and 1117 HYOOA (C-O) carbons HYOOA at about 25.76-34.38 ppm, which are are referred to as stretching ester.”
Salimon 等 - 2013 - Synthesis and optimization ring opening of monoepo DOI: 10.1186/2193-1801-2-429 -
Fluorine (C-F) confidence 1.0
“On the which can be attributable to and stretching viν other hand, brationalmodes,respectively, in 70wt.%PVdF-HFP-30 wt.%LiCF a(CF 2) band originating from PVdF-HFP was found at 3SO 3, 1176cm-1,1177 cm-1and1178cm-1inS30,6ECand6PCsamples.”
Characteristics of PEMA/PVdF-HFP blend polymeric gel films incorporated with lithium triflate salt in electrochromic device DOI: 10.1016/j.ssi.2011.11.035 -
Nitrogen heterocycle confidence 1.0
“The band cm-1 at 1176 corresponded to the stretching vibrations of the imidazolium ring.”
Enhancing the Thermal Stability of Ionogels: Synthesis and Properties of Triple Ionic Liquid/Halloysite/MCC Ionogels DOI: 10.3390/molecules26206198 -
Aromatic ring confidence 1.0
“(O corresponds to oxygen from the corner of the heteropolyanion structure), W-O e-W c IR spectrum of PDPA doped with the PTA heteropolyanions is characterized by the IR (O corresponds to oxygen from the side of the heteropolyanion structure”
The Photoluminescence and Vibrational Properties of Black Phosphorous Sheets Chemically/Electrochemically Functionalized in the Presence of Diphenylamine DOI: 10.3390/polym14214479 -
Hydroxyl (O-H) confidence 1.0
“In the present exν presence of phenol peaks, particularly the Q-branch at periments, phenol was detected in 8 of the 10 static mea16 1176.5cm-1 1150.2cm-1, ν and the peak at is evident.”
Banach 等 - 2021 - Dynamic infrared gas analysis from longleaf pine f DOI: 10.5194/amt-14-2359-2021 -
Carboxyl (COOH) confidence 1.0
“positively weighted peak at 1176 due to Therefore, the loadings plot of PC is related to the 1 changes of carboxylate and hemicellulose in the roots, and proteins may also be involved.”
Soil-applied selenite increases selenium and reduces cadmium in roots of Moringa oleifera DOI: 10.1038/s41598-020-77350-1
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