What absorbs at 3456 cm⁻¹ in an FTIR spectrum?
A band near 3456 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 3456 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 |
|---|---|---|---|
| Hydroxyl (O-H) | 6 | 6 | 1.0 |
| N h | 4 | 3 | 1.0 |
| Water (H2O) | 2 | 2 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Aromatic ring | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| Amide | 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 |
|---|---|---|---|
| polydopamine | 3456, 1543, 1707 | N h, Hydroxyl (O-H) | 1 |
| ZnO | 3456, 1400, 3430 | Hydroxyl (O-H) | 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 3456 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
“Notably, the peak at (sensitive to protein secondary structure) by the malignant spectra demonstrate the highest absorption peaks at amide II band area and band intensity of each of the remaining 1150, 1240, 3456cm-1”
Plasma membrane proteins_ A new probe for the characterization of breast cancer DOI: 10.1016/j.lfs.2019.116777 -
Hydroxyl (O-H) confidence 1.0
“The near-IR broad band centered at 3456 is related to vibrational mode of OH, water and 4.3.”
Ibrahim 等 - 2021 - Gamma-rays interactions on the spectral properties DOI: 10.21608/EJCHEM.2021.55869.3186 -
Alkyl C-H confidence 1.0
“For SOHE, the cm-1 1.40-3.00 ppm (peak 2) and peaks at around ppm (peaks 8, 5, characteristic absorption peak around 3456 had cm-1 and 9) corresponded to protons of methylene.”
Chen 等 - 2020 - Synthesis of a Novel Bio-Oil-Based Hyperbranched E DOI: 10.1021/acsomega.0c00119 -
confidence 1.0
“The FTIR spectrum of the control RR239 (Figure 5a) showed cm-1 a peak at 3456.44 for N-H stretching vibrations of the amino group coupled with stretching cm-1 of O-H group.”
Cossolin 等 - 2019 - DOI: 10.4136/1980-993X -
Hydroxyl (O-H) confidence 1.0
“Each cm-1 spectrum consists of two OH vibration bands: one with the main absorption with E//a at 3456 cm-1 plus a shoulder at the low energy side and one at 3542 with an isotropic absorption behavior.”
Feenstra 等 - 2009 - Hydrogen zoning in zinc-bearing staurolite from a DOI: 10.2138/am.2009.3107 -
Hydroxyl (O-H) confidence 1.0
“1E, the absorption band at 3456 which attributes to the cm-1 stretching vibrations of -OH groups in the PXDDA, broadened and underwent a small shift to 3392 for polydopamine-coated PXDDA.”
Immobilization of FGF on Poly(xylitol dodecanedioic Acid) Polymer for Tissue Regeneration DOI: 10.1038/s41598-020-67261-6 -
Hydroxyl (O-H) confidence 1.0
“Carbon from starting materials could have been incorporated into NRs inadvertently, whereas appearance cm-1 of broad transmission band at 3456 corresponds to O-H stretching of surface adsorbed water molecules [34].”
Doping of Mg on ZnO Nanorods Demonstrated Improved Photocatalytic Degradation and Antimicrobial Potential with Molecular Docking Analysis DOI: 10.1186/s11671-021-03537-8 -
confidence 1.0
“tion) shows the characteristic absorption peaks of the [C cm-1 cm-1 The peaks at 3456 and 3436 correspond to the (N-H) stretching symmetric and asymmetric vibrations.”
Growth, crystal structure, Hirshfeld surface and vibrational properties of a new supramolecular hybrid material: (C4H7N2)2TeBr6 DOI: 10.1007/s00289-021-04053-6
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