What absorbs at 1697 cm⁻¹ in an FTIR spectrum?
A band near 1697 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 1697 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 |
|---|---|---|---|
| Carbonyl (C=O) | 10 | 8 | 1.0 |
| Amide | 9 | 9 | 1.0 |
| Methacrylate | 9 | 9 | 1.0 |
| Acetate | 9 | 9 | 1.0 |
| Carboxyl (COOH) | 8 | 8 | 1.0 |
| Alkyl C-H | 6 | 4 | 1.0 |
| Ketone | 5 | 5 | 1.0 |
| Ester | 5 | 5 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| C-O single bond | 4 | 4 | 1.0 |
| Water (H2O) | 2 | 2 | 1.0 |
| Protein beta sheet | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Hydrogen bond | 2 | 1 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Protein | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Oxalate | 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 |
|---|---|---|---|
| gelatin | 1697, 1652, 3300 | Amide, Methacrylate, Acetate | 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 1697 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
“1697cm-1 phur and thiophene-like structures, respectively, could be (i) The C O stretching in ketones and/or esters 1100cm-1 released to the environment.”
Fernandez-Varela 等 - 2006 - Monitoring photooxidation of the Prestige's oil sp DOI: 10.1016/j.talanta.2005.10.006 -
Amide confidence 1.0
“conformational changes and is usually used to determine spectra.7-11 protein secondary structures based on FTIR According to our results, the second derivative of the Amide I peak had 5 sub-peaks at 1697, 1684, 1654, 1636 and cm-1 1615 (Fig”
Igci 等 - 2017 - Application of Fourier transform infrared spectros DOI: 10.17219/acem/65784 -
Hydroxyl (O-H) confidence 1.0
“cm-1 (aliphatic C H stretching) 2957 mixture Physical cm-1 ( CH stretching) 2928 cm-1 (COOH stretching) 1697 cm-1 (H O H bending) 1652 cm-1 (C O C bending) 1014 618”
Telmisartan complex augments solubility, dissolution and drug delivery in prostate cancer cells DOI: 10.1016/j.carbpol.2013.09.077 -
Oxalate confidence 1.0
“All spectra were normalized to the boehmite peak at 1157 (b) Plot of normalized peak intensities at 1697 from IR spectra at pH 5.1 (filled circles) and pH 2.5 (filled squares) corresponding to inner-sphere oxalate species.”
Yoon 等 - 2004 - Adsorption of organic matter at mineralwater inte DOI: 10.1016/j.gca.2004.04.025 -
Carbonyl (C=O) confidence 1.0
“LLM confirmed rule peak-group candidate”
Aisha 等 - 2013 - Syzygium campanulatum korth methanolic extract inh DOI: 10.1186/1472-6882-13-168 -
Alkyl C-H confidence 1.0
“The FTIR reflectance spectra of pure diabetic mice given IP injections of KBA (Group 3) cm-1 KBA demonstrated characteristic peaks at 3437 showed a normal liver architecture (Figure-6a) with cm-1 (O-H stretching), 2932 (C-H stretching), 169”
Evaluation of the solubility of 11-keto-β-boswellic acid and its histological effect on the diabetic mice liver using a novel technique DOI: 10.14202/vetworld.2021.1797-1803 -
Protein confidence 1.0
“The peak at 1697 in group B showed a red shift with variation in secondary structure of protein for groups B, A, and N.”
Andleeb 等 - 2020 - Hemoglobin structure at higher levels of hemoglobi DOI: 10.1097/CM9.0000000000000801 -
Amide confidence 1.0
“cm-1 bX lation of group (2950-2800 ), valence oscillation thespectrumofPUandGLmatricesexhibitssmallshifts(1-5 2 cm-1 of C=O of the free and bound urethane group (1717 and ) in the positions of absorption band maximums of the cm-1 1697 , res”
Chernonosova 等 - 2018 - Mechanical Properties and Biological Behavior of 3 DOI: 10.1155/2018/1380606
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