What absorbs at 3735 cm⁻¹ in an FTIR spectrum?
A band near 3735 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 6 cited sources
Quick answer
A band near 3735 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) | 4 | 4 | 1.0 |
| Water (H2O) | 2 | 2 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Carbohydrate | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| Nanocellulose | 3735, 1540, 1646 | Hydroxyl (O-H), Carbohydrate | 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 3735 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
-
Silanol (Si-OH) confidence 1.0
“lated silanol peak at 3735 fresh Si-BEA and Ti-BEA samples All changes discussed above relate to silanol groups and do not displayed equivalent peak areas (less than 5% difference) while the necessarily prove any change in the actual Sn sit”
Effect of water treatment on Sn-BEA zeolite: Origin of 960 cm-1 FTIR peak DOI: 10.1016/j.micromeso.2015.02.012 -
Hydroxyl (O-H) confidence 1.0
“only OH-Rb-OH, OH-Rb-F have licic magnesium mica has IR absorptions at 3735 (m), 3695 any expression in the principal OH-stretching region of the”
Synthesis and solid solution in “rubidium richterite”, Rb(NaCa)Mg5Si8O22(OH,F)2 DOI: 10.1007/s00269-019-01037-x -
Hydroxyl (O-H) confidence 1.0
“The transmittance band for -OH at 3735 cm-1, characteristic for the "free" OH cm-1, cellulose [63].”
Bacterial Nanocellulose from Side-Streams of Kombucha Beverages Production: Preparation and Physical-Chemical Properties DOI: 10.3390/polym9080374 -
Hydroxyl (O-H) confidence 1.0
“At 400 and 450 the cm-1), cm-1) 3735 and 3558 -OH stretching vibration or water main chain of EVA broke and released alkanes (2930 olefin (3087 and 1639 cm-1).”
Enhancing Char Formation and Flame Retardancy of Ethylene-Vinyl Acetate Copolymer (EVA)/Aluminum Hydroxide (ATH) Composites by Grafting Ladder Phenyl/Vinyl Polysilsesquioxane (PhVPOSS) DOI: 10.3390/polym15153312 -
confidence 1.0
“Indeed, upon heating main bands at 3745 and 3735 cm1 are found in Y and MOR samples, with additional absorptions at ca.”
Sacchetto 等 - 2013 - The interactions of methyl tert-butyl ether on hig DOI: 10.1039/c3cp51684a -
Hydroxyl (O-H) confidence 1.0
“A broad feature of OH stretching vibration, cm-1 attributable to OH stretching mode of SiOH group, together with a negative band at 3735”
Satter 等 - 2020 - Water-Resistant Pt Sites in Hydrophobic Mesopores DOI: 10.1021/acscatal.0c02816
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