What absorbs at 1523 cm⁻¹ in an FTIR spectrum?
A band near 1523 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 1523 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 | 8 | 8 | 1.0 |
| N h | 4 | 4 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carboxyl (COOH) | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Secondary amine | 2 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Water (H2O) | 1 | 1 | 1.0 |
| Protein beta sheet | 1 | 1 | 1.0 |
| N-O bond | 1 | 1 | 1.0 |
| Lignin | 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 |
|---|---|---|---|
| polyurethane | 1523, 2270, 1700 | Methacrylate, N h, 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 1523 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
“The degradation index can be calculated by using FTIR peak cm(cid:1)1 cm(cid:1)1 C]O eCOe fitting 1640 (amide I, stretching), 1523 (amide II, data to quantify the degradation.”
The durability of clear polyurethane coil coatings studied by FTIR peak fitting DOI: 10.1016/j.polymdegradstab.2012.12.003 -
Hydroxyl (O-H) confidence 1.0
“1523 and (O-H stretch vibration) at 3022”
Akhgari 等 - 2013 - Indomethacin electrospun nanofibers for colonic dr DOI: 10.5681/apb.2013.014 -
confidence 1.0
“The characteristic mono-, di-, and triamine initiators put in relieve the number of urethane groups along the cm-1, υ(C=O) υ(C-O-C) carbonate signals of and around 1741 and 1222 respectively were (δ(N-H) υ(C-N)) PTMC chains with the increas”
Synthesis of Poly(Trimethylene Carbonate) from Amine Group Initiation: Role of Urethane Bonds in the Crystallinity DOI: 10.3390/polym13020280 -
Amide confidence 1.0
“The C-N stretching bands, combined with those of the bending of N-H in the plane, are typically observed at 1523 cm-1 and 1446 cm-1, demonstrating of the bending of N-H in the plane, are typically observed at 1523 cm-1 and 1446 cm-1, demons”
Gregori Valdes 等 - 2018 - Synthesis and Characterization of Isosorbide-Based DOI: 10.3390/polym10101170 -
Lignin confidence 1.0
“Factors describing crystallinity, C=C cm-1 Band (E) at 1523 represents bonds in the arosuch as the total crystallinity index ( T CI ) , lateral - 1 matic rings of lignin (27).”
Hejna 等 - 2017 - Performance properties of rigid polyurethane-polyi DOI: 10.1515/epoly-2017-0012 -
Acetate confidence 1.0
“Strong C-H symmetric stretching 1623 Strong C=O stretching 1523”
Jaisankar 等 - 2020 - Seed microstructures of the Andaman padauk (Pteroc DOI: 10.1007/BF02957854. -
N-O bond confidence 1.0
“The spectrum of CoAl 2O nanocomposites calcined at 1100 °C is also shown by FT-IR, with 4 cm-1 cm-1 3sharp bands between 2893 and 3335 (C-O and C-C vibration) and at 1523 (NO vibration).”
Synthesis and electrochemical performance of α-Al2O3 and M-Al2O4 spinel nanocomposites in hybrid quantum dot-sensitized solar cells DOI: 10.1038/s41598-022-21186-4 -
Amide confidence 1.0
“1554 60%N-Hbending,40%C-Nstretching AmideII(proteins) 1523 80%C=Ostretching,10%N-Hbending, Amide-I:parallelβ-sheets(peptide,protein) 1628”
Fourier-Transform Infrared Spectroscopy as a Discriminatory Tool for Myotonic Dystrophy Type 1 Metabolism: A Pilot Study DOI: 10.3390/ijerph18073800
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