What absorbs at 3737 cm⁻¹ in an FTIR spectrum?
A band near 3737 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 3 cited sources
Quick answer
A band near 3737 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) | 2 | 2 | 1.0 |
| Silanol (Si-OH) | 1 | 1 | 1.0 |
| Ammonium | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
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 3737 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
-
Hydroxyl (O-H) confidence 1.0
“Ti 3737-cm-1 assigned to the O H stretching mode of surface P OH groups, the true reason why band appeared only for are However 43which the are thought to be formed by protonation of the surface PO particle with X Ti= 0.10 is obscure.”
FTIR studies on photocatalytic activity of Ti(IV)-doped calcium hydroxyapatite particles DOI: 10.1016/j.molcata.2012.04.009 -
Hydroxyl (O-H) confidence 1.0
“blank-polymer particle, specific peaks of cromolyn appeared In the range of 3737cm-1, 1604cm-1 C�O, at 3732 to a weak band for the monomeric O-H due to and a band at approximately 1636cm-1, 1477cm-1 stretch band was also observed.”
Alkurdi 等 - 2022 - Development and Evaluation of a Novel Polymer Drug DOI: 10.1155/2022/7903310 -
Ammonium confidence 1.0
“A gradual but not total consumption of 3737 band is also observed, due to the interaction of ammonia with the silanols prevalently located on external cm-1 [Cu2+OHsurfaces of the catalyst.”
Giordanino 等 - 2014 - Interaction of NH3 with Cu-SSZ-13 Catalyst A Comp DOI: 10.1021/jz500241m
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