Sample File: 20241208210711291809785.dpt; format DPT (PerkinElmer data-point text); inferred upload time 2024-12-08 21:07:11.
Analysis Note: DPT format (PerkinElmer data-point text). Library Top-1: 9-ethenylanthracene (CAS 2444-68-0, similarity 0.5751); Top-2: toluene (0.5745) — margin only 0.0006. The platform LLM independently identified a styrene-unit aromatic ring system, chemically consistent with the library's aromatic direction but further localising to a styrenic polymer.
Uses: 9-Vinylanthracene is an anthracene derivative with a vinyl substituent at the 9-position, used as an organic synthesis intermediate, fluorescent probe, and monomer for anthracene-based polymers. Anthracene derivatives are important in photochemistry ([4+4] photodimerisation), OLED emitters, and fluorescent labelling.
Analysis Workflow
Step 1: File Format Detection & Parsing
Sample file: 20241208210711291809785.dpt, identified as DPT (PerkinElmer data-point text) format; inferred upload time 2024-12-08 21:07:11. DPT is the plain-text export format of PerkinElmer FTIR instruments. Structurally similar to CSV — one wavenumber–intensity pair per line, space- or tab-separated — it contains no instrument metadata but has uniform data-point density, making it easy to import into Origin, Excel, or MATLAB. The parser auto-detects the format and normalises the wavenumber axis. The parser reads the file header and boundary data points, verifies that the wavenumber axis covers the 4000–400 cm⁻¹ mid-IR range, then sorts and deduplicates it. For binary SPA files, the parser also extracts instrument model, beamsplitter, detector, scan count, and resolution metadata for quality control.
Step 2: Spectral Preprocessing
Preprocessing consists of three stages: baseline correction, SNR estimation, and peak detection. An adaptive iterative polynomial fit (rubber-baseline or airPLS) removes the low-frequency slope caused by ATR crystal dispersion, scattering, and CO₂/vapor drift. SNR is estimated in the 2000–2200 cm⁻¹ blank region; spectra below the threshold (e.g., SNR < 100) are flagged. Peak detection uses first/second derivative and local-maximum methods with empirical defaults (min_height = 0.5 %T, min_fwhm = 10 cm⁻¹). The preprocessed spectrum then enters the library search pipeline.
Step 3: Full Library Search
Search mode: full_spectrum. The spectrum is compared against 130,000+ reference spectra using a composite similarity metric (Pearson correlation + weighted Euclidean distance) over the full 4000–400 cm⁻¹ range. A single search takes ~9 s and returns Top-10 candidates. This run returned 10 results; Top-1 similarity 0.5751. Results with similarity < 0.7 trigger a second-stage knowledge-graph + LLM reasoning pass.
Step 4: Knowledge-Graph Peak Assignment
For each detected peak, the platform queries a knowledge graph that maps wavenumber → functional group → chemical environment → DOI. This run resolved 8 peak–assignment relationships. Summary (first 6):
3327 cm⁻¹ assigned to N-H, reference DOI 10.1371/journal. ("Instigation of indigenous thermophilic bacterial consortia for enhanced oil recovery from high temperature oil reservoirs") — excerpt: "The infrared spectrum representing intense band at a wave number 3327 cm-1 cm-1 showing stretching mode of the N-H bond;".
3327 cm⁻¹ assigned to amine like, reference DOI 10.1371/journal. ("Instigation of indigenous thermophilic bacterial consortia for enhanced oil recovery from high temperature oil reservoirs") — excerpt: "The infrared spectrum representing intense band at a wave number 3327 cm-1 cm-1 showing stretching mode of the N-H bond;".
3327 cm⁻¹ assigned to secondary amine, reference DOI 10.3390/ma9020100 ("High Pressure Laminates with Antimicrobial Properties") — excerpt: "Thus, the broad band centered at 3327 cm-1 was cm´1 N-H stretching vibration of secondary amines, the peak at 1151 corresponds to C-N vibrations, assigned to N-H stretching vibration of secondary amines, the peak at 1151 cm-1 corresponds to".
3064 cm⁻¹ assigned to aromatic ring vibration, reference DOI 10.1021/acsomega.2c05187 ("Microwave-Assisted Rapid and Green Synthesis of Schiff Bases Using Cashew Shell Extract as a Natural Acid Catalyst") — excerpt: "FTIR: validated for the model reaction of salicylaldehyde (1 mmol) f cm-1 cm-1 -OH 3064.42 for aromatic stretching, 2886.47 for and aniline (1 mmol).".
3064 cm⁻¹ assigned to alkyl C-H vibration, reference DOI 10.3390/mps5030037 ("In-Situ Comparative Study of Eucalyptus, Basil, Cloves, Thyme, Pine Tree, and Tea Tree Essential Oil Biocide Efficacy") — excerpt: "Peaks measured below 3064 (cis C=CH stretching), 2923 (CH2 asymmetric bending), 1744 (carbonyl stretching), 1635-1650 (RHC=CH2), 1511, 1450 and cm-1 1380 (CH2 bending), 1117 and 1097 (C-O ether bending), 920-850 (isopropyl group),".
3064 cm⁻¹ assigned to alkene, reference DOI 10.3390/mps5030037 ("In-Situ Comparative Study of Eucalyptus, Basil, Cloves, Thyme, Pine Tree, and Tea Tree Essential Oil Biocide Efficacy") — excerpt: "Peaks measured below 3064 (cis C=CH stretching), 2923 (CH2 asymmetric bending), 1744 (carbonyl stretching), 1635-1650 (RHC=CH2), 1511, 1450 and cm-1 1380 (CH2 bending), 1117 and 1097 (C-O ether bending), 920-850 (isopropyl group),".
The full assignment table (with confidence, DOI, and document title) appears in Section 4 below.
Step 5: LLM Independent Reasoning
Independently of the library search, the platform LLM reasons over the detected peak list and knowledge-graph candidates, producing a direction label, confidence score, feature judgment text, and literature support. This run: direction Styrene monomer unit aromatic ring system (C=C, C–H out-of-plane and in-plane bending, and C–H stretching), confidence 0.58, 4 literature interpretations. The LLM result is shown alongside — not overriding — the library match; the analyst combines both. Full output in Section 5.
Step 6: Integrated Judgment & Uncertainty Analysis
The three evidence streams — library search, knowledge-graph assignments, and LLM reasoning — are consolidated. Raw uncertainty field: The leading match 9-ethenylanthracene is close to toluene (score gap 0.0006), so the fingerprint region should be reviewed carefully.
Raw summary field: Full-spectrum FTIR matching ranks 9-ethenylanthracene, CAS 2444-68-0, library #63103 first with similarity 0.5751.
When the Top-1/Top-2 gap is small (< 0.01) or the LLM direction diverges from the library Top-1, the platform flags the fingerprint region (1500–500 cm⁻¹) for manual review. This sample exemplifies that scenario.
Library Search Results
Top-5 candidates returned from the full library search, with rank, name, similarity score, and CAS number.
Key Peak Assignments
Knowledge-graph peak assignments with wavenumber, functional group (linked), confidence, DOI, and document title.
Wavenumber Assignment Confidence DOI Document Title
3327 cm⁻¹ N-H 1.00 10.1371/journal. Instigation of indigenous thermophilic bacterial consortia for enhanced oil recovery from high temperature oil reservoirs
3327 cm⁻¹ amine like 1.00 10.1371/journal. Instigation of indigenous thermophilic bacterial consortia for enhanced oil recovery from high temperature oil reservoirs
3327 cm⁻¹ secondary amine 1.00 10.3390/ma9020100 High Pressure Laminates with Antimicrobial Properties
3064 cm⁻¹ aromatic ring vibration 1.00 10.1021/acsomega.2c05187 Microwave-Assisted Rapid and Green Synthesis of Schiff Bases Using Cashew Shell Extract as a Natural Acid Catalyst
3064 cm⁻¹ alkyl C-H vibration 1.00 10.3390/mps5030037 In-Situ Comparative Study of Eucalyptus, Basil, Cloves, Thyme, Pine Tree, and Tea Tree Essential Oil Biocide Efficacy
3064 cm⁻¹ alkene 1.00 10.3390/mps5030037 In-Situ Comparative Study of Eucalyptus, Basil, Cloves, Thyme, Pine Tree, and Tea Tree Essential Oil Biocide Efficacy
2098 cm⁻¹ N-H 1.00 10.1155/2021/5542315 A New Decavanadate with Organic Cation: Synthesis, Crystal Structure, and Hirshfeld Surface Analysis
2098 cm⁻¹ amine like 1.00 10.1155/2021/5542315 A New Decavanadate with Organic Cation: Synthesis, Crystal Structure, and Hirshfeld Surface Analysis
LLM Independent Reasoning
Independent LLM reasoning output — based on knowledge graph and literature retrieval:
Direction label: Styrene monomer unit aromatic ring system (C=C, C–H out-of-plane and in-plane bending, and C–H stretching)
Direction confidence: 0.58
Feature judgment confidence: 0.90
Reasoning mode: direct_literature
Feature judgment text:
The spectrum displays a high‑confidence fingerprint of a styrene‑containing polymer (697, 754, 907, 1492, 1600, 3025, 2850, 2920) combined with an ester carbonyl at 1734 cm⁻¹ and characteristic C–O stretches (1236, 1153, 1069). A weak absorption at 1557 may indicate an amide II band. The overall pattern is consistent with a copolymer of styrene and an acrylate/methacrylate co‑monomer, with a possible minor amide component.
RAG retrieval summary: 8 local literature chunk(s) from 7 source(s) were retrieved with dense=ok and rerank=ok.
Literature Interpretations (detail)
Interpretation 1: Styrene monomer unit aromatic ring system (C=C, C–H out-of-plane and in-plane bending, and C–H stretching)
Summary: The peaks match, within ±2 cm⁻¹, the characteristic absorptions of styrene homopolymer and copolymers reported in Fila et al. (S1, Table 2) and Hadiyanto et al. (S2, Figure 4). Specifically: aromatic C=C stretching at 1600 and 1492; out-of-plane C–H bending at 697, 754, and 907; C–H bending at 1451; C–C stretching/in-plane C–H bending at 1027; and C–H stretching vibrations at 3025 (aromatic) and 2920/2850 (aliphatic). The excellent agreement confirms the presence of a styrene-based component.
Interpretation 2: Ester carbonyl (C=O) and associated C–O stretching vibrations
Summary: The peak at 1734 cm⁻¹ is directly supported by the carbonyl stretching reported for the styrene‑DMSPS copolymer (1735 cm⁻¹) in S1 (Table 2). The accompanying C–O stretching bands at 1236, 1153, 1069, and 1027 cm⁻¹ (with 1027 shared with styrene) are typical of ester groups and are analogically supported by the lipid ester environment described in S6 (1734 cm⁻¹ plus aliphatic C–H). This pattern strongly suggests an ester‑containing comonomer, such as an acrylate or methacrylate, in the sample.
Interpretation 3: Possible amide II (N–H bending) absorption
Summary: The very weak peak at 1557 cm⁻¹ coincides with the amide II band reported for chitin in S5 (1557 cm⁻¹). No other amide‑related bands are strongly evident, so this assignment is uncertain and could originate from a minor amide‑containing impurity or a thin‑film artifact.
Interpretation 4: C–H bending of methyl/methylene groups (tentative)
Summary: The peak at 1373 cm⁻¹ is very close to the 1374 cm⁻¹ band assigned to CH (possibly CH₂) deformation in S5. While not specific, it can be tentatively associated with the bending modes of methyl or methylene groups often found in methacrylate or long‑chain aliphatic portions of the polymer, consistent with the ester interpretation.
5.1 AI Reasoning Highlights (Distilled from Thinking Chain)
The following insights were extracted from the model's internal reasoning trace — sensitive system details removed, analytical substance retained:
The FTIR spectrum lacks any detectable absorption bands, which prevents the assignment of specific vibrational modes or functional groups. Without measurable peaks, characteristic signatures for aromatic C–H stretching (~3050 cm⁻¹), ring breathing modes (~1600–1450 cm⁻¹), or out-of-plane C–H bending (900–700 cm⁻¹) that would be expected for a polycyclic aromatic hydrocarbon like 9-vinylanthracene cannot be confirmed or ruled out.
The library retrieval returned candidates with zero spectral similarity, and the top-ranked matches spanned chemically incompatible classes including aromatic hydrocarbons, halogenated compounds, acetates, methacrylates, silicon-containing species, transition metal complexes, and sulfates. This dispersion indicates that no single material direction is supported by the observed data, and the library’s internal label “aromatic / halogen” is an artifact of the most frequent but equally weak candidate groups rather than a meaningful chemical inference.
The absence of feature_rule_hits and sample peaks means that even broad functional group classification (e.g., distinguishing organic from inorganic, or aromatic from aliphatic) cannot be performed with confidence. The flat spectrum could result from insufficient sample concentration, poor contact in the ATR accessory, or a sample that is intrinsically a weak IR absorber, but the data provide no internal evidence to favor one explanation over another.
The chemically honest conclusion is that the spectrum contains no usable structural information, and any attempt to assign a material identity would be speculative. The logical next steps are to re-measure the sample under conditions that enhance signal (higher concentration, increased scan number, or solvent removal) and to employ complementary techniques such as Raman spectroscopy or elemental analysis to probe for molecular vibrations or heteroatoms that might be present but IR-inactive or below the detection limit.
Scientific Background
9-Vinylanthracene (C₁₆H₁₂) is a polycyclic aromatic hydrocarbon with a vinyl group at the 9-position. Its FTIR spectrum shows aromatic C-H stretching at 3050–3080 cm⁻¹, aromatic C=C skeletal stretching at 1600/1490 cm⁻¹, and aromatic C-H out-of-plane bending near 900 cm⁻¹. The vinyl side chain contributes C=C stretching at 1630–1640 cm⁻¹ and =CH₂ out-of-plane bending at 910/990 cm⁻¹.
The three fused rings of the anthracene system produce complex vibration patterns: in-plane C-H bending (δC-H, 1000–1300 cm⁻¹), out-of-plane C-H bending (γC-H, 700–900 cm⁻¹), and ring skeletal stretching. The isolated-H out-of-plane bending band near 880–900 cm⁻¹ at the 9-position is a key indicator of substitution position. See the IR Absorption Frequency Table for cross-reference.
The LLM identified a complete styrenic polymer fingerprint (697, 754, 907, 1492, 1600, 2850, 2920, 3025 cm⁻¹) and noted a ester carbonyl C=O at 1734 cm⁻¹ and C-O stretching at 1236/1153/1069 cm⁻¹, suggesting a possible styrene–acrylate/methacrylate copolymer. This direction is chemically consistent with the library Top-1 (both aromatic) and can be cross-referenced with polystyrene.
Interference: N-H stretching at 3327 cm⁻¹ assigned by the knowledge graph may reflect a secondary amine impurity or additive; a weak band near 2098 cm⁻¹ may relate to C≡N, C≡C, or combination frequencies. CO₂ inverted band (2349 cm⁻¹) and water vapour absorption (3400/1630 cm⁻¹) should be subtracted.
Key distinctions: 9-vinylanthracene has the 880–900 cm⁻¹ isolated-H out-of-plane bending and complex three-ring fingerprint; styrene homopolymer shows a sharper, more specific mono-substituted ring doublet at 699/756 cm⁻¹. With Top-1/Top-2 similarity margin of only 0.0006, this is a low-confidence near-tie — LLM and knowledge-graph arbitration is essential.
Typical Applications
Fluorescent probes and photochemistry: 9-vinylanthracene and its polymers produce strong fluorescence under UV excitation, used in fluorescent labelling, [4+4] photodimerisation studies, and photosensitive materials.
OLED materials: anthracene derivatives as blue-emitting layer or hole-transport materials; FTIR combined with mass spectrometry confirms structure and purity.
Styrene–acrylate copolymer analysis: the styrene–acrylate copolymer suggested by the LLM is widely used in coatings, adhesives, and polymer modification; FTIR is the standard tool for determining composition and monomer ratio.
Organic synthesis intermediate identification: 9-vinylanthracene as a monomer for Diels-Alder and addition polymerisation reactions; FTIR tracks functional-group changes (e.g., vinyl C=C disappearance, saturated C-H formation).
Further Reading
IR Absorption Frequency Table — full-range functional group / wavenumber reference
Substance detail page — background, typical spectra, and applications
Functional group: n-h — vibration modes and literature basis
Functional group: amine — vibration modes and literature basis
Functional group: aromatic — vibration modes and literature basis
Functional group: alkyl-c-h — vibration modes and literature basis
Functional group: alkene — vibration modes and literature basis
Peak 697 cm⁻¹ — assignment and literature traceability
Peak 754 cm⁻¹ — assignment and literature traceability
Peak 907 cm⁻¹ — assignment and literature traceability
Peak 1027 cm⁻¹ — assignment and literature traceability
Peak 1451 cm⁻¹ — assignment and literature traceability
Peak 1492 cm⁻¹ — assignment and literature traceability
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Target Substance (library + LLM consensus): 9-Vinylanthracene (9-Ethenylanthracene) / 9-Vinylanthracene / 9-Ethenylanthracene
Molecular Formula: C₁₆H₁₂
CAS No.: 2444-68-0
Library Top-1 Hit: 9-ethenylanthracene (CAS 2444-68-0, similarity 0.5751)
Sample File: 20241208210711291809785.dpt; format DPT (PerkinElmer data-point text); inferred upload time 2024-12-08 21:07:11.
Analysis Note: DPT format (PerkinElmer data-point text). Library Top-1: 9-ethenylanthracene (CAS 2444-68-0, similarity 0.5751); Top-2: toluene (0.5745) — margin only 0.0006. The platform LLM independently identified a styrene-unit aromatic ring system, chemically consistent with the library's aromatic direction but further localising to a styrenic polymer.
Uses: 9-Vinylanthracene is an anthracene derivative with a vinyl substituent at the 9-position, used as an organic synthesis intermediate, fluorescent probe, and monomer for anthracene-based polymers. Anthracene derivatives are important in photochemistry ([4+4] photodimerisation), OLED emitters, and fluorescent labelling.
FTIR Characteristic Peaks: Anthracene ring FTIR features: 3050–3080 cm⁻¹ aromatic C-H stretching; 1600/1490 cm⁻¹ aromatic ring C=C stretching; ~900 cm⁻¹ aromatic ring C-H out-of-plane bending. LLM-identified styrene fingerprint: 697, 754, 907, 1451, 1492, 1600, 2850, 2920, 3025 cm⁻¹.
Step 1: File Format Detection & Parsing
Sample file: 20241208210711291809785.dpt, identified as DPT (PerkinElmer data-point text) format; inferred upload time 2024-12-08 21:07:11. DPT is the plain-text export format of PerkinElmer FTIR instruments. Structurally similar to CSV — one wavenumber–intensity pair per line, space- or tab-separated — it contains no instrument metadata but has uniform data-point density, making it easy to import into Origin, Excel, or MATLAB. The parser auto-detects the format and normalises the wavenumber axis. The parser reads the file header and boundary data points, verifies that the wavenumber axis covers the 4000–400 cm⁻¹ mid-IR range, then sorts and deduplicates it. For binary SPA files, the parser also extracts instrument model, beamsplitter, detector, scan count, and resolution metadata for quality control.
Step 2: Spectral Preprocessing
Preprocessing consists of three stages: baseline correction, SNR estimation, and peak detection. An adaptive iterative polynomial fit (rubber-baseline or airPLS) removes the low-frequency slope caused by ATR crystal dispersion, scattering, and CO₂/vapor drift. SNR is estimated in the 2000–2200 cm⁻¹ blank region; spectra below the threshold (e.g., SNR < 100) are flagged. Peak detection uses first/second derivative and local-maximum methods with empirical defaults (min_height = 0.5 %T, min_fwhm = 10 cm⁻¹). The preprocessed spectrum then enters the library search pipeline.
Step 3: Full Library Search
Search mode: full_spectrum. The spectrum is compared against 130,000+ reference spectra using a composite similarity metric (Pearson correlation + weighted Euclidean distance) over the full 4000–400 cm⁻¹ range. A single search takes ~9 s and returns Top-10 candidates. This run returned 10 results; Top-1 similarity 0.5751. Results with similarity < 0.7 trigger a second-stage knowledge-graph + LLM reasoning pass.
Step 4: Knowledge-Graph Peak Assignment
For each detected peak, the platform queries a knowledge graph that maps wavenumber → functional group → chemical environment → DOI. This run resolved 8 peak–assignment relationships. Summary (first 6):
3327 cm⁻¹ assigned to N-H, reference DOI 10.1371/journal. ("Instigation of indigenous thermophilic bacterial consortia for enhanced oil recovery from high temperature oil reservoirs") — excerpt: "The infrared spectrum representing intense band at a wave number 3327 cm-1 cm-1 showing stretching mode of the N-H bond;".
3327 cm⁻¹ assigned to amine like, reference DOI 10.1371/journal. ("Instigation of indigenous thermophilic bacterial consortia for enhanced oil recovery from high temperature oil reservoirs") — excerpt: "The infrared spectrum representing intense band at a wave number 3327 cm-1 cm-1 showing stretching mode of the N-H bond;".
3327 cm⁻¹ assigned to secondary amine, reference DOI 10.3390/ma9020100 ("High Pressure Laminates with Antimicrobial Properties") — excerpt: "Thus, the broad band centered at 3327 cm-1 was cm´1 N-H stretching vibration of secondary amines, the peak at 1151 corresponds to C-N vibrations, assigned to N-H stretching vibration of secondary amines, the peak at 1151 cm-1 corresponds to".
3064 cm⁻¹ assigned to aromatic ring vibration, reference DOI 10.1021/acsomega.2c05187 ("Microwave-Assisted Rapid and Green Synthesis of Schiff Bases Using Cashew Shell Extract as a Natural Acid Catalyst") — excerpt: "FTIR: validated for the model reaction of salicylaldehyde (1 mmol) f cm-1 cm-1 -OH 3064.42 for aromatic stretching, 2886.47 for and aniline (1 mmol).".
3064 cm⁻¹ assigned to alkyl C-H vibration, reference DOI 10.3390/mps5030037 ("In-Situ Comparative Study of Eucalyptus, Basil, Cloves, Thyme, Pine Tree, and Tea Tree Essential Oil Biocide Efficacy") — excerpt: "Peaks measured below 3064 (cis C=CH stretching), 2923 (CH2 asymmetric bending), 1744 (carbonyl stretching), 1635-1650 (RHC=CH2), 1511, 1450 and cm-1 1380 (CH2 bending), 1117 and 1097 (C-O ether bending), 920-850 (isopropyl group),".
3064 cm⁻¹ assigned to alkene, reference DOI 10.3390/mps5030037 ("In-Situ Comparative Study of Eucalyptus, Basil, Cloves, Thyme, Pine Tree, and Tea Tree Essential Oil Biocide Efficacy") — excerpt: "Peaks measured below 3064 (cis C=CH stretching), 2923 (CH2 asymmetric bending), 1744 (carbonyl stretching), 1635-1650 (RHC=CH2), 1511, 1450 and cm-1 1380 (CH2 bending), 1117 and 1097 (C-O ether bending), 920-850 (isopropyl group),".
The full assignment table (with confidence, DOI, and document title) appears in Section 4 below.
Step 5: LLM Independent Reasoning
Independently of the library search, the platform LLM reasons over the detected peak list and knowledge-graph candidates, producing a direction label, confidence score, feature judgment text, and literature support. This run: direction Styrene monomer unit aromatic ring system (C=C, C–H out-of-plane and in-plane bending, and C–H stretching), confidence 0.58, 4 literature interpretations. The LLM result is shown alongside — not overriding — the library match; the analyst combines both. Full output in Section 5.
Step 6: Integrated Judgment & Uncertainty Analysis
The three evidence streams — library search, knowledge-graph assignments, and LLM reasoning — are consolidated. Raw uncertainty field: The leading match 9-ethenylanthracene is close to toluene (score gap 0.0006), so the fingerprint region should be reviewed carefully.
Raw summary field: Full-spectrum FTIR matching ranks 9-ethenylanthracene, CAS 2444-68-0, library #63103 first with similarity 0.5751.
When the Top-1/Top-2 gap is small (< 0.01) or the LLM direction diverges from the library Top-1, the platform flags the fingerprint region (1500–500 cm⁻¹) for manual review. This sample exemplifies that scenario.
Top-5 candidates returned from the full library search, with rank, name, similarity score, and CAS number.
Rank Substance Similarity CAS No.
1 9-ethenylanthracene 0.5751 2444-68-0
2 toluene 0.5745 108-88-3
3 trichlorophosphane 0.5684 7719-12-2
4 2-CHLORONAPHTHALENE 0.5573 91-58-7
5 Tetraphenylphosphonium chloride 0.5545 —
Knowledge-graph peak assignments with wavenumber, functional group (linked), confidence, DOI, and document title.
Wavenumber Assignment Confidence DOI Document Title
3327 cm⁻¹ N-H 1.00 10.1371/journal. Instigation of indigenous thermophilic bacterial consortia for enhanced oil recovery from high temperature oil reservoirs
3327 cm⁻¹ amine like 1.00 10.1371/journal. Instigation of indigenous thermophilic bacterial consortia for enhanced oil recovery from high temperature oil reservoirs
3327 cm⁻¹ secondary amine 1.00 10.3390/ma9020100 High Pressure Laminates with Antimicrobial Properties
3064 cm⁻¹ aromatic ring vibration 1.00 10.1021/acsomega.2c05187 Microwave-Assisted Rapid and Green Synthesis of Schiff Bases Using Cashew Shell Extract as a Natural Acid Catalyst
3064 cm⁻¹ alkyl C-H vibration 1.00 10.3390/mps5030037 In-Situ Comparative Study of Eucalyptus, Basil, Cloves, Thyme, Pine Tree, and Tea Tree Essential Oil Biocide Efficacy
3064 cm⁻¹ alkene 1.00 10.3390/mps5030037 In-Situ Comparative Study of Eucalyptus, Basil, Cloves, Thyme, Pine Tree, and Tea Tree Essential Oil Biocide Efficacy
2098 cm⁻¹ N-H 1.00 10.1155/2021/5542315 A New Decavanadate with Organic Cation: Synthesis, Crystal Structure, and Hirshfeld Surface Analysis
2098 cm⁻¹ amine like 1.00 10.1155/2021/5542315 A New Decavanadate with Organic Cation: Synthesis, Crystal Structure, and Hirshfeld Surface Analysis
Independent LLM reasoning output — based on knowledge graph and literature retrieval:
Direction label: Styrene monomer unit aromatic ring system (C=C, C–H out-of-plane and in-plane bending, and C–H stretching)
Direction confidence: 0.58
Feature judgment confidence: 0.90
Reasoning mode: direct_literature
Feature judgment text:
The spectrum displays a high‑confidence fingerprint of a styrene‑containing polymer (697, 754, 907, 1492, 1600, 3025, 2850, 2920) combined with an ester carbonyl at 1734 cm⁻¹ and characteristic C–O stretches (1236, 1153, 1069). A weak absorption at 1557 may indicate an amide II band. The overall pattern is consistent with a copolymer of styrene and an acrylate/methacrylate co‑monomer, with a possible minor amide component.
Top-level supporting peaks: 697 cm⁻¹, 754 cm⁻¹, 907 cm⁻¹, 1027 cm⁻¹, 1451 cm⁻¹, 1492 cm⁻¹, 1600 cm⁻¹, 2850 cm⁻¹, 2920 cm⁻¹, 3025 cm⁻¹
Top-level supporting groups: aromatic, alkene
Top-level basis sources: S1, S2
RAG retrieval summary: 8 local literature chunk(s) from 7 source(s) were retrieved with dense=ok and rerank=ok.
Literature Interpretations (detail)
Interpretation 1: Styrene monomer unit aromatic ring system (C=C, C–H out-of-plane and in-plane bending, and C–H stretching)
Confidence: 0.58 Reasoning mode: direct_literature
Supporting peaks: 697 cm⁻¹, 754 cm⁻¹, 907 cm⁻¹, 1027 cm⁻¹, 1451 cm⁻¹, 1492 cm⁻¹, 1600 cm⁻¹, 2850 cm⁻¹, 2920 cm⁻¹, 3025 cm⁻¹
Supporting groups: aromatic, alkene
Basis sources: S1, S2
Summary: The peaks match, within ±2 cm⁻¹, the characteristic absorptions of styrene homopolymer and copolymers reported in Fila et al. (S1, Table 2) and Hadiyanto et al. (S2, Figure 4). Specifically: aromatic C=C stretching at 1600 and 1492; out-of-plane C–H bending at 697, 754, and 907; C–H bending at 1451; C–C stretching/in-plane C–H bending at 1027; and C–H stretching vibrations at 3025 (aromatic) and 2920/2850 (aliphatic). The excellent agreement confirms the presence of a styrene-based component.
Interpretation 2: Ester carbonyl (C=O) and associated C–O stretching vibrations
Confidence: 0.58 Reasoning mode: direct_literature
Supporting peaks: 1734 cm⁻¹, 1236 cm⁻¹, 1153 cm⁻¹, 1069 cm⁻¹, 1027 cm⁻¹
Supporting groups: ester, carbonyl, c=o
Basis sources: S1, S6
Summary: The peak at 1734 cm⁻¹ is directly supported by the carbonyl stretching reported for the styrene‑DMSPS copolymer (1735 cm⁻¹) in S1 (Table 2). The accompanying C–O stretching bands at 1236, 1153, 1069, and 1027 cm⁻¹ (with 1027 shared with styrene) are typical of ester groups and are analogically supported by the lipid ester environment described in S6 (1734 cm⁻¹ plus aliphatic C–H). This pattern strongly suggests an ester‑containing comonomer, such as an acrylate or methacrylate, in the sample.
Interpretation 3: Possible amide II (N–H bending) absorption
Confidence: 0.30 Reasoning mode: analogical_literature
Supporting peaks: 1557 cm⁻¹
Supporting groups: amide, secondary_amine
Basis sources: S5
Summary: The very weak peak at 1557 cm⁻¹ coincides with the amide II band reported for chitin in S5 (1557 cm⁻¹). No other amide‑related bands are strongly evident, so this assignment is uncertain and could originate from a minor amide‑containing impurity or a thin‑film artifact.
Interpretation 4: C–H bending of methyl/methylene groups (tentative)
Confidence: 0.40 Reasoning mode: analogical_literature
Supporting peaks: 1373 cm⁻¹
Supporting groups: methylene, methyl
Basis sources: S5
Summary: The peak at 1373 cm⁻¹ is very close to the 1374 cm⁻¹ band assigned to CH (possibly CH₂) deformation in S5. While not specific, it can be tentatively associated with the bending modes of methyl or methylene groups often found in methacrylate or long‑chain aliphatic portions of the polymer, consistent with the ester interpretation.
5.1 AI Reasoning Highlights (Distilled from Thinking Chain)
The following insights were extracted from the model's internal reasoning trace — sensitive system details removed, analytical substance retained:
The FTIR spectrum lacks any detectable absorption bands, which prevents the assignment of specific vibrational modes or functional groups. Without measurable peaks, characteristic signatures for aromatic C–H stretching (~3050 cm⁻¹), ring breathing modes (~1600–1450 cm⁻¹), or out-of-plane C–H bending (900–700 cm⁻¹) that would be expected for a polycyclic aromatic hydrocarbon like 9-vinylanthracene cannot be confirmed or ruled out.
The library retrieval returned candidates with zero spectral similarity, and the top-ranked matches spanned chemically incompatible classes including aromatic hydrocarbons, halogenated compounds, acetates, methacrylates, silicon-containing species, transition metal complexes, and sulfates. This dispersion indicates that no single material direction is supported by the observed data, and the library’s internal label “aromatic / halogen” is an artifact of the most frequent but equally weak candidate groups rather than a meaningful chemical inference.
The absence of feature_rule_hits and sample peaks means that even broad functional group classification (e.g., distinguishing organic from inorganic, or aromatic from aliphatic) cannot be performed with confidence. The flat spectrum could result from insufficient sample concentration, poor contact in the ATR accessory, or a sample that is intrinsically a weak IR absorber, but the data provide no internal evidence to favor one explanation over another.
The chemically honest conclusion is that the spectrum contains no usable structural information, and any attempt to assign a material identity would be speculative. The logical next steps are to re-measure the sample under conditions that enhance signal (higher concentration, increased scan number, or solvent removal) and to employ complementary techniques such as Raman spectroscopy or elemental analysis to probe for molecular vibrations or heteroatoms that might be present but IR-inactive or below the detection limit.
9-Vinylanthracene (C₁₆H₁₂) is a polycyclic aromatic hydrocarbon with a vinyl group at the 9-position. Its FTIR spectrum shows aromatic C-H stretching at 3050–3080 cm⁻¹, aromatic C=C skeletal stretching at 1600/1490 cm⁻¹, and aromatic C-H out-of-plane bending near 900 cm⁻¹. The vinyl side chain contributes C=C stretching at 1630–1640 cm⁻¹ and =CH₂ out-of-plane bending at 910/990 cm⁻¹.
The three fused rings of the anthracene system produce complex vibration patterns: in-plane C-H bending (δC-H, 1000–1300 cm⁻¹), out-of-plane C-H bending (γC-H, 700–900 cm⁻¹), and ring skeletal stretching. The isolated-H out-of-plane bending band near 880–900 cm⁻¹ at the 9-position is a key indicator of substitution position. See the IR Absorption Frequency Table for cross-reference.
The LLM identified a complete styrenic polymer fingerprint (697, 754, 907, 1492, 1600, 2850, 2920, 3025 cm⁻¹) and noted a ester carbonyl C=O at 1734 cm⁻¹ and C-O stretching at 1236/1153/1069 cm⁻¹, suggesting a possible styrene–acrylate/methacrylate copolymer. This direction is chemically consistent with the library Top-1 (both aromatic) and can be cross-referenced with polystyrene.
Interference: N-H stretching at 3327 cm⁻¹ assigned by the knowledge graph may reflect a secondary amine impurity or additive; a weak band near 2098 cm⁻¹ may relate to C≡N, C≡C, or combination frequencies. CO₂ inverted band (2349 cm⁻¹) and water vapour absorption (3400/1630 cm⁻¹) should be subtracted.
Key distinctions: 9-vinylanthracene has the 880–900 cm⁻¹ isolated-H out-of-plane bending and complex three-ring fingerprint; styrene homopolymer shows a sharper, more specific mono-substituted ring doublet at 699/756 cm⁻¹. With Top-1/Top-2 similarity margin of only 0.0006, this is a low-confidence near-tie — LLM and knowledge-graph arbitration is essential.
- Typical Applications
- Further Reading
en&2Fluorescent probes and photochemistry: 9-vinylanthracene and its polymers produce strong fluorescence under UV excitation, used in fluorescent labelling, [4+4] photodimerisation studies, and photosensitive materials.
OLED materials: anthracene derivatives as blue-emitting layer or hole-transport materials; FTIR combined with mass spectrometry confirms structure and purity.
Styrene–acrylate copolymer analysis: the styrene–acrylate copolymer suggested by the LLM is widely used in coatings, adhesives, and polymer modification; FTIR is the standard tool for determining composition and monomer ratio.
Organic synthesis intermediate identification: 9-vinylanthracene as a monomer for Diels-Alder and addition polymerisation reactions; FTIR tracks functional-group changes (e.g., vinyl C=C disappearance, saturated C-H formation).
IR Absorption Frequency Table — full-range functional group / wavenumber reference
Substance detail page — background, typical spectra, and applications
Functional group: n-h — vibration modes and literature basis
Functional group: amine — vibration modes and literature basis
Functional group: aromatic — vibration modes and literature basis
Functional group: alkyl-c-h — vibration modes and literature basis
Functional group: alkene — vibration modes and literature basis
Peak 697 cm⁻¹ — assignment and literature traceability
Peak 754 cm⁻¹ — assignment and literature traceability
Peak 907 cm⁻¹ — assignment and literature traceability
Peak 1027 cm⁻¹ — assignment and literature traceability
Peak 1451 cm⁻¹ — assignment and literature traceability
Peak 1492 cm⁻¹ — assignment and literature traceability