What absorbs at 1652 cm⁻¹ in an FTIR spectrum?
A band near 1652 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 1652 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 |
|---|---|---|---|
| Amide | 48 | 46 | 1.0 |
| Carbonyl (C=O) | 24 | 21 | 1.0 |
| Methacrylate | 16 | 15 | 1.0 |
| Acetate | 16 | 15 | 1.0 |
| Carboxyl (COOH) | 16 | 13 | 1.0 |
| Ketone | 12 | 11 | 1.0 |
| Ester | 12 | 11 | 1.0 |
| Protein alpha helix | 11 | 11 | 1.0 |
| N h | 10 | 9 | 1.0 |
| Alkyl C-H | 8 | 8 | 1.0 |
| Protein | 7 | 7 | 1.0 |
| Secondary amine | 7 | 6 | 1.0 |
| C n single bond | 6 | 6 | 1.0 |
| Protein beta sheet | 6 | 6 | 1.0 |
| Hydroxyl (O-H) | 6 | 5 | 1.0 |
| C c single bond | 4 | 4 | 1.0 |
| Methoxy (OCH3) | 4 | 4 | 1.0 |
| C-O single bond | 4 | 4 | 1.0 |
| Water (H2O) | 2 | 2 | 1.0 |
| Protein random coil | 1 | 1 | 1.0 |
| Metal oxygen | 1 | 1 | 1.0 |
| Protein beta turn | 1 | 1 | 1.0 |
| Lipid | 1 | 1 | 1.0 |
| Amine primary | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 1.0 |
| Nucleic acid | 1 | 1 | 1.0 |
| C#c | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Adsorbed carbon monoxide | 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 | 1652, 1650, 1655 | Amide, Acetate, Methacrylate | 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 1652 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
-
Amide confidence 1.0
“A tentative assignment of the nine bands (1695, 1682, 1668, 1660, cm-1) in the amide I region 1652, 1639, 1628, 1619, 1610 cm-1), (1700-1600 found to change during heating, is discussed”
Bertram 等 - 2006 - Heat-induced changes in myofibrillar protein struc DOI: 10.1021/jf0514726 -
Carboxyl (COOH) confidence 1.0
“LLM confirmed rule peak-group candidate”
Modification of curcumin-loaded liposome with edible compounds to enhance ability of crossing blood brain barrier DOI: 10.1016/j.colsurfa.2020.124862 -
Protein beta sheet confidence 1.0
“1747 β-Sheet of amide I [59-61] ](C-O) vibration ](C-N) 1652 δ(N-H),”
Hssaini 等 - 2022 - Do Pollination and Pollen Sources Affect Fig Seed DOI: 10.1155/2022/3969165 -
Carbonyl (C=O) confidence 1.0
“cm-1 cm-1 1652 corresponds to vibration of carbonyl bond (amide I) while peak at 1579 corresponds to N-H bending of primary amine probably overlapped by N-H bending (amide II) cm-1 cm-1 of typical O=C-NHR groups and peak at 1359 and 1318 fo”
Jaiswal 和 Dhayal - 2020 - Preparation of 2D coatings of functionally graded DOI: 10.1016/j.matchemphys.2020.122663 -
Hydroxyl (O-H) confidence 1.0
“cm-1 Telmisartan 3059 (aromatic C H stretching) Complex (aromatic C H stretching) 3058 cm-1 2957 (aliphatic C H stretching) cm-1 cm-1 1699 (COOH stretching) 1652 (H O H bending) cm-1 cm-1 1599 (C C aromatic band and stretching) 1014 (C O C”
Telmisartan complex augments solubility, dissolution and drug delivery in prostate cancer cells DOI: 10.1016/j.carbpol.2013.09.077 -
Amide confidence 1.0
“vC@O 1647 Conjugated carbonyl (amide I band) 1652 1651 1644 1643 1638 1646 1546 vas NO2 (amide II band) 1543”
Differential identification of mushrooms sclerotia by IR macro-fingerprint method DOI: 10.1016/j.saa.2015.07.054 -
Protein beta sheet confidence 1.0
“The decrease in lipid and protein contents is Table 4 Results of curve Control 10 Days exposure 30 Days exposure Assignments fitting analysis expressed as a function of percentage Wave num- % Area Wave num- % Area Wave num- % Area (cm-1) (c”
Spectral profile index changes as biomarker of toxicity in Catla catla (Hamilton, 1822) edible fish studied using FTIR and principle component analysis DOI: 10.1007/s42452-020-3001-z -
Amide confidence 1.0
“Second-derivative speccm(cid:1)1 amide I peak at 1652 and shoulders at 1625 and tral analysis was applied to locate the position of the overcm(cid:1)1 1608 were observed for the 1KBr samples.”
Pressure dependence of human fibrinogen correlated to the conformational [alpha]-helix to [beta]-sheet transition: An Fourier transform infrared study microspectroscopic study DOI: 10.1002/bip.20012
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