What absorbs at 2143 cm⁻¹ in an FTIR spectrum?
A band near 2143 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 5 cited sources
Quick answer
A band near 2143 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 |
|---|---|---|---|
| Thiocarbonyl | 1 | 1 | 1.0 |
| Adsorbed carbon monoxide | 1 | 1 | 1.0 |
| Methoxy (OCH3) | 1 | 1 | 1.0 |
| Methacrylate | 1 | 1 | 1.0 |
| C-O single bond | 1 | 1 | 1.0 |
| Acetate | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 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 |
|---|---|---|---|
| hydroxyapatite | 2143, 1620, 1639 | Methacrylate | 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 2143 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
-
Alkyl C-H confidence 1.0
“2883.58 CH Stretching Methyne NACH3 2831.50 CH stretching Methylamine C@C 2142.91 stretching Alkynes PAO 2077.33 bond”
Spectral characterization of hydroxyapatite extracted from Black Sumatra and Fighting cock bone samples: A comparative analysis DOI: 10.1016/j.sjbs.2020.11.020 -
Acetate confidence 1.0
“The position of the observed C-O stretching in monocarbonyls 2 cm-1) (to be compared with vibration of gaseous CO, 2143 is the compromise between three”
Giordanino 等 - 2013 - Characterization of Cu-exchanged SSZ-13 a compara DOI: 10.1039/c3dt50732g -
Adsorbed carbon monoxide confidence 1.0
“2173 should be ascribed to the linear CO species on the Pt-SnO species without x cm-1 backdonation, because of the stretching frequency measured at 2143 cm-1 for the free CO molecule in d-π* a backdonation, because of the stretching frequen”
Co-Aromatization of n-Butane and Methanol over PtSnK-Mo/ZSM-5 Zeolite Catalysts: The Promotion Effect of Ball-Milling DOI: 10.3390/catal8080307 -
Thiocarbonyl confidence 1.0
“Peak at 2106 (Figure cm-1 5C) belongs to the characteristic peak of N=C=S stretch (at 2143 for pure NCO-C 6H 4N NCS solid).”
Zhang 和 Yan - 2010 - Analytical strategies for characterizing the surfa DOI: 10.1007/s00216-009-2996-1. -
confidence 0.8
“IR band at 2143 cm-1 via its oxygen.”
Moussa 等 - 2018 - Nature of Active Nickel Sites and Initiation Mecha DOI: 10.1021/acscatal.7b03970
Have a spectrum with this band?
Upload your FTIR spectrum and get a full interpretation report — peak assignments with literature citations, library matches, and a confidence-rated evidence chain — in seconds.