What absorbs at 2175 cm⁻¹ in an FTIR spectrum?
A band near 2175 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
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Silanol (Si-OH) | 2 | 1 | 1.0 |
| C#c | 1 | 1 | 1.0 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Bronsted acid site | 1 | 1 | 1.0 |
| Bromine | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 0.9 |
| Methyl | 1 | 1 | 0.9 |
| Hydroxyl (O-H) | 1 | 0 | 1.0 |
| Lewis acid site | 1 | 0 | 1.0 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Bromine confidence 1.0
“FULL PAPER cm-1, cm-1, a signal centred at 2175 due to the stretching mode of CO mode, which in the liquid phase appears at 1611 is very interacting with Brønsted acid sites, is present in all spectra, sensitive to the acidity of the OH sit”
Erigoni 等 - 2016 - Creating Accessible Active Sites in Hierarchical M DOI: 10.1038/ncomms9633. -
C#c confidence 1.0
“Characterization of Isolated Strains cm-1, 2175.12 which is the seventh peak, is due to the vibrations of alkynes (carbon-carbon triple bond).”
Shakeri 等 - 2022 - Biosynthesis of Selenium Nanoparticles and Evaluat DOI: 10.1155/2022/4118048 -
confidence 0.9
“Single band centered at ~2175 cm-1 for free CNR.”
Blouin 和 Olson - 2010 - The Stretching Frequencies of Bound Alkyl Isocyani DOI: 10.1021/bi100172c. -
Methyl confidence 0.9
“Symmetric CH3 stretching and asymmetric CH2 stretching”
A comparison of chitosan properties after extraction from shrimp shells by diluted and concentrated acids DOI: 10.1016/j.heliyon.2020.e03486 -
Silanol (Si-OH) confidence 0.8
“Band at 2175 for acetonitrile on silanols”
In Situ FT-IR Characterization of CuZnZr/Ferrierite Hybrid Catalysts for One-Pot CO2-to-DME Conversion DOI: 10.3390/ma11112275 -
confidence 0.8
“Text: 'band at 2175 and the CuN'”
Santoro 等 - 2015 - Synthesis, characterization and cellular location DOI: 10.1039/c4dt03598d
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