What absorbs at 1741 cm⁻¹ in an FTIR spectrum?
A band near 1741 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 1741 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) | 39 | 37 | 1.0 |
| Ester | 34 | 34 | 1.0 |
| Carboxyl (COOH) | 29 | 29 | 1.0 |
| Amide | 29 | 29 | 1.0 |
| Methacrylate | 28 | 28 | 1.0 |
| Acetate | 28 | 28 | 1.0 |
| Ketone | 25 | 25 | 1.0 |
| Alkyl C-H | 4 | 4 | 1.0 |
| Methoxy (OCH3) | 3 | 3 | 1.0 |
| Triglyceride | 3 | 2 | 1.0 |
| Hydrogen bond | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Protein | 2 | 2 | 1.0 |
| Phospholipid | 2 | 2 | 1.0 |
| Lipid | 2 | 2 | 1.0 |
| Silicon-oxygen (Si-O) | 2 | 2 | 1.0 |
| Silicon (Si) | 2 | 2 | 1.0 |
| Carbohydrate | 2 | 2 | 1.0 |
| Protein alpha helix | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| Silicon hydride | 1 | 1 | 1.0 |
| Fatty acid | 1 | 1 | 1.0 |
| Methyl | 1 | 1 | 1.0 |
| Acetyl | 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 |
|---|---|---|---|
| pectin | 1741, 1746, 1150 | Carboxyl (COOH), Amide, Carbonyl (C=O) | 1 |
| chitosan | 1741, 1650, 1655 | Amide | 1 |
| chitin | 1741, 1650, 1655 | Amide | 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 1741 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
-
Carbohydrate confidence 1.0
“Keywords: cm-1, cm-1 cm-1 spectroscopy shows the CMSS hydrogel absorption peaks at 1741 1605 and 1430 which Carboxymethyl starch indicates the substitution of carboxymethyl group of modified sago starch.”
Preparation and characterization of irradiated carboxymethyl sago starch-acid hydrogel and its application as metal scavenger in aqueous solution DOI: 10.1016/j.carbpol.2015.11.028 -
Carbonyl (C=O) confidence 1.0
“The ester carbonyl band lay in 1741 of control plant cell walls in roots.”
Changes in chemical composition and structure of root cell wall of citrus rootstock seedlings in response to boron deficiency by FTIR spectroscopy DOI: 10.1080/14620316.2017.1362327 -
Acetate confidence 1.0
“Biomass C--O, cm(cid:0) 1, C-O, C-H surements, it was observed peaks at 1741, 1328, and 1229 characteristics of and Heavy metals stretching bands, respectively.”
Nickel adsorption from aqueous solution using lemon peel biomass chemically modified with TiO2 nanoparticles DOI: 10.1016/j.scp.2020.100299 -
confidence 1.0
“The new FTIR absorption peak at 1741 represents the formation of CdSe QDs [19] on the surface of the silica spheres.”
Kim 等 - 2015 - Controlled growth of CdSe quantum dots on silica s DOI: 10.1117/12.2187697 -
Ester confidence 1.0
“1(a)] shows cm(cid:1)1 peaks characteristic of PPDO at 2943 due cm(cid:1)1 C(cid:1)(cid:1)H to the stretching, at 1741 due to the cm(cid:1)1 C¼¼O stretching of ester, and at 1135 due Table 1.”
Surface-initiated ring-opening polymerization of p-dioxanone on Wang resin bead DOI: 10.1002/pola.22457 -
Carboxyl (COOH) confidence 1.0
“the presence of alkanes was intensified in SynS and a new vibration of esters at 1741 However, the strong vibrations for flavonoids, phenolics, and carboxylic acids were preHowever, the strong vibrations for flavonoids, phenolics, and carbo”
Biosynthesis and Characterization of Calcium Oxide Nanoparticles from Citrullus colocynthis Fruit Extracts; Their Biocompatibility and Bioactivities DOI: 10.3390/ma16072768 -
Hydrogen bond confidence 1.0
“Furthermore, it can be seen that the absorpcm-1 cm-1 interactions and hydrogen bonding (Silva-Weiss, Bifani, Ihl, tion peak located at 1741 was shifted to 1734 with”
Nisar 等 - 2019 - Citrus pectin films enriched with thinned young ap DOI: 10.1080/19476337.2019.1640798 -
Amide confidence 1.0
“The C-O-C cm-1 cm-1 stretching was observed at 1016 and amide I and II bands were observed at 1741 cm-1 cm-1 and 1395 respectively.”
Sudatta 等 - 2020 - Extraction, characterization and antimicrobial act DOI: 10.1016/j.ijbiomac.2020.06.291
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