What absorbs at 1170 cm⁻¹ in an FTIR spectrum?
A band near 1170 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 1170 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 |
|---|---|---|---|
| Methacrylate | 14 | 14 | 1.0 |
| C-O single bond | 14 | 14 | 1.0 |
| Acetate | 14 | 14 | 1.0 |
| Methoxy (OCH3) | 13 | 13 | 1.0 |
| C c single bond | 5 | 5 | 1.0 |
| Ester | 4 | 4 | 1.0 |
| Phosphate (PO4) | 4 | 4 | 1.0 |
| Alkyl C-H | 4 | 4 | 1.0 |
| Fluorine (C-F) | 3 | 3 | 1.0 |
| Amide | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 3 | 2 | 1.0 |
| Carbonyl (C=O) | 3 | 2 | 1.0 |
| Silicon-oxygen (Si-O) | 3 | 2 | 1.0 |
| N-O bond | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Nucleic acid | 2 | 2 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| S eq o | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 1 | 1.0 |
| Triglyceride | 1 | 1 | 1.0 |
| Ketone | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Ammonium | 1 | 1 | 1.0 |
| Nitrogen heterocycle | 1 | 1 | 1.0 |
| Phospholipid | 1 | 1 | 0.7 |
| Silicon nitrogen | 1 | 0 | 1.0 |
| Silicon hydride | 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 | 1170, 1650, 1655 | Acetate, Methacrylate, C-O single bond | 1 |
| PVDF | 1170, 1160, 840 | Methacrylate, Acetate | 1 |
| MgO | 1170, 699, 874 | Methoxy (OCH3), Methacrylate, C-O single bond | 1 |
| lignin | 1170, 1035, 1510 | Methacrylate, Acetate, C-O single bond | 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 1170 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
-
N-O bond confidence 1.0
“film 1170cm-1 1180cm-1 same from to suggesting possible transformation from to This showed no film apparent defect on its surface.”
Arshad 等 - 2019 - Dielectric and Structural Properties of Poly(vinyl DOI: 10.1155/2019/5961563 -
S eq o confidence 1.0
“(cm(cid:3)1) Band Vibration mode Main attribution Raw material Standard b-D-glucan M26/08 M49/07 M23/08 C@O 1647 v Conjugated carbonyl 1648 1655 1655 1646 CAH das 1445 CH3, CH2 1431 1436 1431 1420 CAH ds 1379 CH3 1374 1375 1375 1377 SAO 135”
Choong 等 - 2014 - Identification of geographical origin of Lignosus DOI: 10.1016/j.molstruc.2014.04.001 -
C c single bond confidence 1.0
“The peaks around 1170 are mainly the absorption peaks of the C-C and C-O originating from the structure of the phenols and ethers.”
Liang 等 - 2020 - Thermal Kinetics of a Lignin-Based Flame Retardant DOI: 10.3390/polym12092123 -
Alkyl C-H confidence 1.0
“(C=N) appear at 1570 Bending vibration charactercm-1 istic peaks around 1449 corresponding to the side cm-1 024 chain -CH CH vibration peak, a peak of 1170 was 3.45 2 Water”
Thermal stability and lifetime of [AMIM]Cl-PFSA composite membranes DOI: 10.1007/s10973-016-6065-7 -
Ammonium confidence 1.0
“((cid:24) cm-1) corresponding to note that one particular peak 1170 cm-1 of NO at 1289, 1504, and 1613 correspond to the species ((cid:228) s(NH 3)) coordinated to to the symmetric deformation of NH that were previously discussed in Figure”
Pena 等 - 2004 - Identification of surface species on titania-suppo DOI: 10.1021/jp0313122 -
Alkyl C-H confidence 1.0
“The peaks at around cm-1 1170 and 2933 are related to vibration of -CN and -CH groups [21-23].”
Rupiasih 等 - 2019 - The Current-Voltage Properties of ChAgNP Composit DOI: 10.1088/1757-899X/515/1/012064 -
Phosphate (PO4) confidence 1.0
“also reveals a P=O peak at 1170 This suggests a strongly linked interaction between the TPP phosphoric and chitosan ammonium ions of the two reactive systems [34].”
Sahudin 等 - 2022 - Enhancement of Skin Permeation and Penetration of DOI: 10.3390/cosmetics9060114 -
S eq o confidence 1.0
“Indications for determine the formation of sulfonate in the PDO can be seen from the emergence of the S=O stretch cm-1 peak at wavelengths 1170,79 (PDOS) which did not appear at the PDO as shown in figure 6.”
Sampora 等 - 2017 - Study of Synthesis Polyethylene glycol oleate Sulf DOI: 10.1088/1742-6596/909/1/012078
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