What absorbs at 745 cm⁻¹ in an FTIR spectrum?
A band near 745 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 745 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.
可能的官能团归属
| 官能团 | 支持性事实 | 引用来源 | 最高置信度 |
|---|---|---|---|
| Alkyl C-H | 3 | 3 | 1.0 |
| Metal oxygen | 3 | 3 | 1.0 |
| Chlorine | 3 | 3 | 1.0 |
| Hydroxyl (O-H) | 2 | 2 | 1.0 |
| C-O single bond | 2 | 2 | 1.0 |
| Hydrogen bond | 1 | 1 | 1.0 |
| Phosphate (PO4) | 1 | 1 | 1.0 |
| C-S single bond | 1 | 1 | 1.0 |
| Siloxane (Si-O-Si) | 1 | 1 | 1.0 |
| Silicon-oxygen (Si-O) | 1 | 1 | 1.0 |
| Silicon (Si) | 1 | 1 | 1.0 |
| Boron nitrogen | 1 | 1 | 0.9 |
| Aromatic ring | 1 | 1 | 0.7 |
排名反映了累积的文献证据，而非单一的权威规则。请始终对照您的样品背景进行确认。
Possible materials
| 材料 | 支持峰 | Overlapping groups | 引用来源 |
|---|---|---|---|
| TiO2 | 745, 1700, 1093 | Metal oxygen, Hydroxyl (O-H), Alkyl C-H | 1 |
| TiO | 745, 1730, 1699 | Alkyl C-H, Hydroxyl (O-H), Metal oxygen | 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 745 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.
这些分配背后的文献
-
Silicon (Si) 置信度 1.0
“In the Al-MCM-41/UiO-66 (2) spectra, the absorption peak cm-1 appeared at wave number 744.55 indicates the vibration of the Si-O-Si molecule.”
Synthesis and catalytic activity of mesoporous Al-MCM-41/UiO-66 for esterification of oleic acid DOI: 10.1063/1.5082500 -
Alkyl C-H 置信度 1.0
“ran'sstrongestvibrationalband,theν vibrationalbandnear As stated, a second method was also used to analyze 19 745cm-1 C-H corresponding to the out-of-plane bend (Shiand/or corroborate the different stages of the burn, whereby manouchi, 1972”
Banach 等 - 2021 - Dynamic infrared gas analysis from longleaf pine f DOI: 10.5194/amt-14-2359-2021 -
置信度 1.0
“cm-1 cm-1 cm-1 3284.2 (N-H stretching), 1672.0 (C=O stretching), 1591.8 (N-H bending), 1322.5 stretching), 1442.1 cm-1 (S-O stretching) and 744.6 cm-1 (C-Cl stretching).”
Garbacz 和 Wesolowski - 2018 - DSC, FTIR and Raman Spectroscopy Coupled with Mult DOI: 10.3390/molecules23092136 -
C-O single bond 置信度 1.0
“and the lowest peak shifted from 745 to from 773 to concentration is due to (1) dilution of ether groups with the 740cm-1.”
Kim 等 - 2020 - Lithium Salt Dissociation in Diblock Copolymer Ele DOI: 10.3389/fenrg.2020.569442 -
C-S single bond 置信度 1.0
“LiTFSI spectrum manifests two weak peaks at 745 and 804 The first peak is S-N stretching mode, whereas the latter peak is a combination of C-S stretching and S-N asymmetric Polymers 2016, 8, 179 10 of 16”
Liew 等 - 2016 - Poly(Acrylic acid)-Based Hybrid Inorganic-Organic DOI: 10.3390/polym8050179 -
Metal oxygen 置信度 1.0
“In the spectrum of ZnMOF-BTA, metallic-oxygen bands are observed at 435 cm-1 and 463 cm-1 and are assigned to stretching vibrations of Zn-O bonds in the MOF [32], and bands observed at 745 cm-1 and 753 cm-1 correspond to the characteristic”
Synthesis, Characterization and Investigation of Anticorrosion Properties of an Innovative Metal–Organic Framework, ZnMOF-BTA, on Carbon Steel in HCl Solution DOI: 10.3390/coatings12091288 -
Phosphate (PO4) 置信度 1.0
“The bands at around 745 assigned to asymmetric stretching vibrations of the P-O- (Moustafa et al., P rings 1998) The bands at around cm-1 910 are related to P-O-P symmetric stretch-”
Saddeek 和 Abo-Naf - 2012 - Influence of MoO3 on the Structure of Lithium Alum DOI: 10.2478/v10168-012-0043-2 -
C-O single bond 置信度 1.0
“cm-1 cm-1 C-OH is related to of primary and secondary The advent frequency bands at 745 and 540”
Enhanced sunlight photocatalytic activity and biosafety of marine-driven synthesized cerium oxide nanoparticles DOI: 10.1038/s41598-021-94327-w
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