STRUCTURALLY AWARE APPROACH TO THE INTERPRETATION OF VIBRATIONAL SPECTRA

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STRUCTURALLY AWARE APPROACH

TO THE INTERPRETATIONOF VIBRATIONAL SPECTRA

Eugene Karpushkin,Yury Zhukov,

Andrey Bogomolov

www.acdlabs.com


What makes “manual” IR interpretation challenging?

IR spectral signals are “volatile” due to overlap and influence of chemical environment

Many different factors to take into account simultaneously

Correlation tables and charts take expert’s time and efforts

Structurally aware software required!


ACD/Labs is a structurally aware software

Drawn Structure

Chemicaldatabases

Systematicnaming

Spectra

Chromatograms NMR spectralprediction

Phys-chemproperty

prediction


What does structural awareness mean?

Easy drawing of chemical structures 2D-cleaning/3D-optimization Attaching molecule to a spectrum Fragment structure analysis

Structure/substructure DB search Reporting with structures

Peak-to-fragment assignment


Spectrum Interpretation ChartRaw

Spectrum

Report

Confirmed Structure

Hit List

Peak Table

Possible Fragments

Hypothetic Structures

PeakAnalysis

DB Search

Compare

Knowledge Base

Construct

Verify

Assign

Find Repeating

More Data


Possible Fragments

Searching Database: Example 1Raw

Spectrum

Report

Confirmed Structure

Hit List

Peak Table


PeakAnalysis

DB Search

Compare

Knowledge Base

Construct

Verify

Assign

Find Repeating

More Data


Searching Database: Example 2Raw

Spectrum

Report

Confirmed Structure

Hit List

Peak Table

Possible Fragments


PeakAnalysis

DB Search

Compare

Knowledge Base

Construct

Verify

Assign

Find Repeating

More Data

Candidate fragments:CH3 – 9 hits; NO2 – 7 hits; aromatics - 4 hits


Peak AnalysisRaw

Spectrum

Report

Confirmed Structure

Hit List

Peak Table

Possible Fragments


PeakAnalysis

DB Search

Compare

Knowledge Base

Construct

Verify

Assign

Find Repeating

More Data


Knowledge Base: classes

alkanes, alkenes, alkynes, allenes, alicyclic compounds

alcohols, ethers, aldehydes, ketones, non-carbon acids, peroxy compounds, halogen compounds

carboxylic acids, halogenides, anhydrides, carbonates, carboxylates, esters

aromatic compounds, heterocycles amides, amines, imides, imines,

nitrocompounds, other N compounds B, P, S, Se, Si compounds inorganic ions


Knowledge Base

Knowledge BaseRaw

Spectrum

Report

Confirmed Structure

Hit List

Peak Table

Possible Fragments


PeakAnalysis

DB Search

Compare

Construct

Verify

Assign

Find Repeating

More Data


ACD/Labs Fragment Object

“Atom” descriptors: * A [C,H] AnyC SatC Aryl Hal [N,O,S]Bond descriptors:Ar D Rn Ch

*

O Aryl

O*

*

*

*

Ch

Ar

Ar

Ar

Ar

Ar

Ar

N+

O

O-A

A[N,O]

H

Ar

Ar


Powerful means selective


PCA for Fragment FormulationExample set:

15 chloroanhydrides

+19 aldehydes

=34 compounds

*825 wavelengths

O

R H

O

R Cl


PCA for Fragment Formulation:Captured Variance

O

OH

O

Br

CH3O

O

OCH3

O

Cl

Cl

CH3


PCA for Fragment Formulation: Scores Plot – Structure Classes






PCA for Fragment Formulation:Bi-Plot Reveals Spectral Features

1718 cm-1

1742 cm-1

1802 cm-1


PCA for Fragment Formulation


Knowledge Base is Interactive


Structure VerificationRaw

Spectrum

Report

Confirmed Structure

Hit List

Peak Table

Possible Fragments


PeakAnalysis

DB Search

Compare

Knowledge Base

Construct

Verify

Assign

Find Repeating

More Data


Successful Verification is… Failed One

Raw Spectrum

Report

Confirmed Structure

Hit List

Peak Table

Possible Fragments


PeakAnalysis

DB Search

Compare

Knowledge Base

Construct

Verify

Assign

Find Repeating

More Data


Assignment and ReportingRaw

Spectrum

Report

Confirmed Structure

Hit List

Peak Table

Possible Fragments


PeakAnalysis

DB Search

Compare

Knowledge Base

Construct

Verify

Assign

Find Repeating

More Data


Conclusions1. Full qualitative analysis spectral interpretation tools in the same product interface

2. Authentic Fragment Object provides almost unlimited flexibility in specifying group environment

3. Advanced tool for fragmental analysis of molecules

4. Knowledge Base with about 2400 highly selective fragments

5. Facilitated IR spectral interpretation and automated structure verification


Acknowledgements

Yury Zhukov Alexey Pastutsan

Documents

STRUCTURALLY AWARE APPROACH TO THE INTERPRETATION OF VIBRATIONAL SPECTRA