What absorbs at 1577 cm⁻¹ in an FTIR spectrum?
A band near 1577 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
Quick answer
A band near 1577 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 |
|---|---|---|---|
| Amide | 8 | 8 | 1.0 |
| Aromatic ring | 6 | 5 | 1.0 |
| Carboxyl (COOH) | 6 | 4 | 1.0 |
| Alkene (C=C) | 3 | 3 | 1.0 |
| Carbonyl (C=O) | 3 | 2 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| Methacrylate | 2 | 2 | 1.0 |
| Ketone | 2 | 2 | 1.0 |
| Ester | 2 | 2 | 1.0 |
| Acetate | 2 | 2 | 1.0 |
| N h | 2 | 2 | 1.0 |
| Secondary amine | 1 | 1 | 1.0 |
| C n single bond | 1 | 1 | 1.0 |
| Ring structure | 1 | 1 | 1.0 |
| C c single bond | 1 | 1 | 1.0 |
| Alkyl C-H | 1 | 1 | 1.0 |
| C=n | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Silanol (Si-OH) | 1 | 1 | 1.0 |
| Urethane | 1 | 1 | 0.9 |
| Lewis acid site | 1 | 0 | 0.7 |
Ranking reflects accumulated literature evidence, not a single fixed rule. Always confirm against your sample context.
Possible materials
| Material | Supporting peaks | Overlapping groups | Cited sources |
|---|---|---|---|
| hydrogel | 1577, 1632, 1062 | Amide, Carboxyl (COOH) | 1 |
| GO | 1577, 1720, 1182 | Amide, Carboxyl (COOH) | 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 1577 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
“Nandanwar R, Singh P, Syed F, Haque FZ (2014) Preparation of cm1 cm1 and at 966.42 shows the bending TiO2/SiO2 nanocomposite with non-ionic surfactants via sol-gel and S F2, vibrations of Si-OH and Si-O-Si bonds in S D2 processandtheirphoto”
Haque 等 - 2018 - Effect of Different Acids and Solvents on Optical DOI: 10.1007/s12633-016-9464-2 -
C=n confidence 1.0
“LLM confirmed rule peak-group candidate”
Shamsuddin 和 Abd Karim - 2016 - Synthesis and characterization of N, N'-bis[4-[1-( DOI: 10.1063/1.4966745 -
Aromatic ring confidence 1.0
“2 Aromatic C=C stretching 1577.41 and 1485.46 1577.39 and 1485.43 2 Aromatic C=C stretching 1577.41 and 1485.46 1577.39 and 1485.43 3”
Suhalim 等 - 2023 - Impact of Silver-Decorated Graphene Oxide (Ag-GO) DOI: 10.3390/membranes13060602 -
Amide confidence 1.0
“nebrodensis mushrooms exhibited similar spectroscopic characteristics and positively correlated with regions at 2925 and 2859 cm-1 (aliphatic compounds), 1745 cm-1 (phospholipids), 1577 cm-1 (amide II Foods 2020, 9, x FOR PEER REVIEW 8 of 1”
Pleurotus Mushrooms Content in Glucans and Ergosterol Assessed by ATR-FTIR Spectroscopy and Multivariate Analysis DOI: 10.3390/foods9040535 -
Hydroxyl (O-H) confidence 1.0
“(black) depicts that PEGCD BSA is found vibration (1577 which may come from itaconic acid or cm(cid:4)1), -O-H -N-H to have and/or stretching (3415 and 3111 citraconic acid or trans-aconitic acid resulting as an intermecm(cid:4)1), -C-H ]C-”
Insight into carbon quantum dot–vesicles interactions: role of functional groups DOI: 10.1039/d1ra08809b -
Amide confidence 1.0
“The maxima of am- (C=O), ide band I, at 1670 cm-1 and amide band II, δ(N-H), at 1577 cm-1, were shifted by 23 and 26 units, respectively, to higher wavenumbers, relative to their position in the spectrum of homopolymer.”
Modified Sulfanilamide Release from Intelligent Poly(N-isopropylacrylamide) Hydrogels DOI: 10.3390/pharmaceutics15061749 -
Acetate confidence 1.0
“The peaks at 1577 cm-1 and 1480 cm-1 correspond to the vibration of O-C=O and C-H of cm-1 cm-1 The peaks at 1577 and 1480 correspond to the vibration of O-C=O and C-H GO.”
Synthesis of Green and Red-Emitting Polymethyl Methacrylate Composites Grafted from ZnAl2O4:Mn-Bonded GO via Surface-Initiated Atom Transfer Radical Polymerization DOI: 10.3390/polym14173689 -
Aromatic ring confidence 1.0
“LLM confirmed rule peak-group candidate”
Garcia-Ivars 等 - 2014 - Development of fouling-resistant polyethersulfone DOI: 10.1016/j.seppur.2014.07.056.
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