What absorbs at 1406 cm⁻¹ in an FTIR spectrum?
A band near 1406 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 1406 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 | 4 | 4 | 1.0 |
| Carboxyl (COOH) | 4 | 4 | 1.0 |
| Secondary amine | 3 | 3 | 1.0 |
| Aromatic ring | 3 | 2 | 1.0 |
| C n single bond | 2 | 2 | 1.0 |
| Alkyl C-H | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Carbonyl (C=O) | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Alkene (C=C) | 1 | 1 | 1.0 |
| Phosphorus | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| Carbonate | 1 | 1 | 1.0 |
| N h | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Lignin | 1 | 1 | 1.0 |
| Boron nitrogen | 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 | 1406, 1650, 1655 | Amide | 1 |
| bacterial cellulose | 1406, 1050, 1631 | Amide | 1 |
| ZnO | 1406, 1400, 3430 | Amide | 1 |
| polyaniline | 1406, 1565, 1570 | Aromatic ring, Amide, Secondary amine | 1 |
| apatite | 1406, 3053, 1640 | Amide, Carboxyl (COOH) | 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 1406 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
-
confidence 1.0
“The band at cm-1 ~1406 has been identified as a B1 signal, which corresponds to "v3a" in Fleet et al.”
Clark 等 - 2016 - Quantification of CO2 concentration in apatite DOI: 10.2138/am-2016-5661 -
Hydroxyl (O-H) confidence 1.0
“The band at 1406 was attributed to phenolic -OH (of lignin) and aliphatic C-H for methyl groups and this band also decreased for BC adhered jute mat and neat BC (Rashid, Kait, and Murugesan 2016: Viet and Tho 2017).”
In-situ Production and Collection of Bacterial Cellulose on Jute and Flax Mats by Static Cultivation DOI: 10.1080/15440478.2020.1870638 -
C-O single bond confidence 1.0
“cm-1, vibration at 1666 shifts to 1645 the C-N stretching vibration at 1438 shifts to 1406 cm-1 cm-1 and the C-OH stretching vibration at 1073 shifts to 1037 (Figure 3).”
Synthesis, Characterization, and Antibacterial Activity of Cross-Linked Chitosan-Glutaraldehyde DOI: 10.3390/md11051534 -
Acetate confidence 1.0
“FTIR spectrum shows absorption bands at cm-1, wavenumbers 1406 and 1565 which correspond to The transmission plots of ZnO nanorods at different MW C=O asymmetric and symmetric stretching modes, powers of 136, 264, 440, 616, and 800 W are sh”
Muzaffar 等 - 2020 - Microwave assisted tuning of optical and magnetic DOI: 10.1007/s10971-020-05290-3 -
confidence 1.0
“Polymerization of aniline takes place over fine grade zinc fercorresponds to stretching vibration of benzenoid ring, CAH 1406cm(cid:2)1 rite particles.”
Dielectric relaxation and ac conductivity of polyaniline⠍zinc ferrite composite DOI: 10.1016/j.compositesb.2012.01.090 -
Acetate confidence 1.0
“cm-1,1406 cm-1 cm-1 assigned to C=O GO peaks at 1092 and 1728 with corresponding functional cm-1 cm-1 groups (C-O), (O-H) and (C=O) respectively as well as peaks at 855 and 553 having functional group”
Antibacterial and in vivo toxicological studies of Bi2O3/CuO/GO nanocomposite synthesized via cost effective methods DOI: 10.1038/s41598-022-17332-7 -
N h confidence 1.0
“For (CN stretching vibration of imine group), 1522,1483cm(cid:3)1 example, 60.53% of CHD was released from F1 compared to (NH bending vibration of secondary amine and 1406cm(cid:3)1 (C@C 94.27% of CHD which was released from F5.”
Al-Ani 等 - 2019 - The effect of the source and the concentration of DOI: 10.1016/j.jsps.2019.04.012 -
Carbonate confidence 1.0
“cm-1 The intense bands at 1406 and 1027 which are ascribed to lead white, calcite, and”
New Insights into the Medieval Hispano-Muslim Panel Painting: The Alfarje Found in a Balearic Casal (Spain) DOI: 10.3390/molecules28031235
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