What absorbs at 1659 cm⁻¹ in an FTIR spectrum?
A band near 1659 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
Possible functional-group assignments
| Functional group | Supporting facts | Cited sources | Top confidence |
|---|---|---|---|
| Amide | 5 | 4 | 0.9 |
| Carbonyl (C=O) | 3 | 2 | 0.9 |
| Carboxyl (COOH) | 1 | 1 | 1.0 |
| Alkene (C=C) | 1 | 1 | 0.9 |
| N h | 1 | 1 | 0.8 |
| Protein alpha helix | 1 | 1 | 0.8 |
Ranking reflects accumulated literature evidence, not a single authoritative rule. Always confirm against your sample context.
Literature behind these assignments
-
Carboxyl (COOH) confidence 1.0
“Explicit assignment: 'COO- absorptions, at 1659 ... which corresponded to of uronic acids'”
Trigui 等 - 2018 - Physicochemical properties of water-soluble polysa DOI: 10.1016/j.ijbiomac.2018.05.202 -
Amide confidence 0.9
“Same assignment.”
Raghav 等 - 2017 - Nonenzymatic glycosylation of human serum albumin DOI: 10.1371/journal. -
Amide confidence 0.9
“Explicit assignment in text.”
Tyan 等 - 2004 - Proteomic profiling of platelet proteins by trypsi DOI: 10.1002/jbm.a.30129 -
Amide confidence 0.9
“Absorption band around 1659 cm-1 assigned to amide I (C=O stretching).”
Cavalu 等 - 2021 - Nano-Scale Modifications of Amniotic Membrane Indu DOI: 10.3390/ma14040863 -
Alkene (C=C) confidence 0.9
“Explicit assignment: '1658.84 ... due to -C=C'”
Jabar 等 - 2020 - Kinetics and mechanisms of congo-red dye removal f DOI: 10.1007/s13201-020-01221-3 -
Carbonyl (C=O) confidence 0.9
“From snippet: 1659-1692 (C=O)”
Mumtaz 等 - 2018 - SYNTHESIS, CHARACTERIZATION AND UREASE INHIBITION DOI: 10.1016/j.ejmech.2011.09.009. -
Amide confidence 0.9
“Text: 'bands at 1659 and 1590cm-1 represent amide and amin'”
Naghibzadeh 等 - 2010 - An Insight into the Interactions between alpha-Toc DOI: 10.1155/2010/818717 -
confidence 0.9
“Explicit assignment for PIP”
Yang 等 - 2022 - Spray-Drying of Hydroxypropyl beta-Cyclodextrin Mi DOI: 10.3390/cryst12050596
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