Spectrochemistry

Spectrochemistry is the application of spectroscopy in several fields of chemistry. It includes analysis of spectra in chemical terms, and use of spectra to derive the structure of chemical compounds, and also to qualitatively and quantitively analyze their presence in the sample. It is a method of chemical analysis that relies on the measurement of wavelengths and intensity of electromagnetic radiation.[1]

[2] Dichloromethane IR Spectrum

History
Isaac Newton - English mathematician and Physicist
Joseph Von Fraunhofer- Bavarian Physicist
Gustav Kirchhoff - German Physicist
Thomas Young - British Polymath

It was not until 1666 that Isaac Newton showed that white lights from the sun could be dissipated into a continuous series of colors. So Newton introduced the concept which he called spectrum to describe this phenomenon. He used a small aperture to define the beam of light, a lens to collimate it, a glass prism to disperse it, and a screen to display the resulting spectrum. Newton's analysis of light was the beginning of the science of spectroscopy. Later, It became clear that the Sun's radiation might have components outside the visible portion of the spectrum. In 1800 William Hershel showed that the sun's radiation extended into infrared, and in 1801 John Wilhelm Ritter also made a similar observation in the ultraviolet. Joseph Von Fraunhofer extended Newton's discovery by observing the sun's spectrum when sufficiently dispersed was blocked by a fine dark lines now known as Fraunhofer lines. Fraunhofer also developed diffracting grating, which disperses the lights in much the same way as does a glass prism but with some advantages. the grating applied interference of lights to produce diffraction provides a direct measuring of wavelengths of diffracted beams. So by extending Thomas Young's study which demonstrated that a light beam passes slit emerges in patterns of light and dark edges Fraunhofer was able to directly measure the wavelengths of spectral lines. However, despite his enormous achievements, Fraunhofer was unable to understand the origins of the special line in which he observed. It was not until 33 years after his passing that Gustav Kirchhoff established that each element and compound has its unique spectrum and that by studying the spectrum of an unknown source, one could determine its chemical compositions, and with these advancements, spectroscopy became a truly scientific method of analyzing the structures of chemical compounds. Therefore, by recognizing that each atom and molecule has its spectrum Kirchhoff and Robert Bunsen established spectroscopy as a scientific tool for probing atomic and molecular structures and founded the field of spectrochemical analysis for analyzing the composition of materials.[3]

Robert Bunsen - German Chemist

IR Spectra Tables & Charts

IR Spectrum Table by Frequency[4]

Frequency Range Absorption (cm−1) Appearance Group Compound Class Comments
4000–3000 cm−1 3700-3584 medium, sharp O-H stretching alcohol free
3550-3200 strong, broad O-H stretching alcohol intermolecular bonded
3500 medium N-H stretching primary amine
3400
3400-3300 medium N-H stretching aliphatic primary amine
3330-3250
3350-3310 medium N-H stretching secondary amine
3300-2500 strong, broad O-H stretching carboxylic acid usually centered on 3000 cm−1
3200-2700 weak, broad O-H stretching alcohol intramolecular bonded
3000-2800 strong, broad N-H stretching amine salt
3000–2500 cm−1
3000–2500 cm−1 3333-3267 strong, sharp C-H stretching alkyne
3100-3000 medium C-H stretching alkene
3000-2840 medium C-H stretching alkane
2830-2695 medium C-H stretching aldehyde doublet
2600-2550 weak S-H stretching thiol
2400–2000 cm−1
2400–2000 cm−1 2349 strong O=C=O stretching carbon dioxide
2275-2250 strong, broad N=C=O stretching isocyanate
2260-2222 weak CΞN stretching nitrile
2260-2190 weak CΞC stretching alkyne disubstituted
2175-2140 strong S-CΞN stretching thiocyanate
2160-2120 strong N=N=N stretching azide
2150 C=C=O stretching ketene
2145-2120 strong N=C=N stretching carbodiimide
2140-2100 weak CΞC stretching alkyne monosubstituted
2140-1990 strong N=C=S stretching isothiocyanate
2000-1900 medium C=C=C stretching allene
2000 C=C=N stretching ketenimine
2000–1650 cm−1
2000–1650 cm−1 2000-1650 weak C-H bending aromatic compound overtone
1870-1540
1818 strong C=O stretching anhydride
1750
1815-1785 strong C=O stretching acid halide
1800-1770 strong C=O stretching conjugated acid halide
1775 strong C=O stretching conjugated anhydride
1720
1770-1780 strong C=O stretching vinyl / phenyl ester
1760 strong C=O stretching carboxylic acid monomer
1750-1735 strong C=O stretching esters 6-membered lactone
1750-1735 strong C=O stretching δ-lactone γ: 1770
1745 strong C=O stretching cyclopentanone
1740-1720 strong C=O stretching aldehyde
1730-1715 strong C=O stretching α,β-unsaturated ester or formates
1725-1705 strong C=O stretching aliphatic ketone or cyclohexanone or cyclopentenone
1720-1706 strong C=O stretching carboxylic acid dimer
1710-1680 strong C=O stretching conjugated acid dimer
1710-1685 strong C=O stretching conjugated aldehyde
1690 strong C=O stretching primary amide free (associated: 1650)
1690-1640 medium C=N stretching imine / oxime
1685-1666 strong C=O stretching conjugated ketone
1680 strong C=O stretching secondary amide free (associated: 1640)
1680 strong C=O stretching tertiary amide free (associated: 1630)
1650 strong C=O stretching δ-lactam γ: 1750-1700 β: 1760-1730
1670–1600 cm−1
1670–1600 cm−1 1678-1668 weak C=C stretching alkene disubstituted (trans)
1675-1665 weak C=C stretching alkene trisubstituted
1675-1665 weak C=C stretching alkene tetrasubstituted
1662-1626 medium C=C stretching alkene disubstituted (cis)
1658-1648 medium C=C stretching alkene vinylidene
1650-1600 medium C=C stretching conjugated alkene
1650-1580 medium N-H bending amine
1650-1566 medium C=C stretching cyclic alkene
1648-1638 strong C=C stretching alkene monosubstituted
1620-1610 strong C=C stretching α,β-unsaturated ketone
1600–1300 cm−1
1600–1300 cm−1 1550-1500 strong N-O stretching nitro compound
1372-1290
1465 medium C-H bending alkane methylene group
1450 medium C-H bending alkane methyl group
1375
1390-1380 medium C-H bending aldehyde
1385-1380 medium C-H bending alkane gem dimethyl
1370-1365
1400–1000 cm−1
1400–1000 cm−1 1440-1395 medium O-H bending carboxylic acid
1420-1330 medium O-H bending alcohol
1415-1380 strong S=O stretching sulfate
1200-1185
1410-1380 strong S=O stretching sulfonyl chloride
1204-1177
1400-1000 strong C-F stretching fluoro compound
1390-1310 medium O-H bending phenol
1372-1335 strong S=O stretching sulfonate
1195-1168
1370-1335 strong S=O stretching sulfonamide
1170-1155
1350-1342 strong S=O stretching sulfonic acid anhydrous
1165-1150 hydrate: 1230-1120
1350-1300 strong S=O stretching sulfone
1160-1120
1342-1266 strong C-N stretching aromatic amine
1310-1250 strong C-O stretching aromatic ester
1275-1200 strong C-O stretching alkyl aryl ether
1075-1020
1250-1020 medium C-N stretching amine
1225-1200 strong C-O stretching vinyl ether
1075-1020
1210-1163 strong C-O stretching ester
1205-1124 strong C-O stretching tertiary alcohol
1150-1085 strong C-O stretching aliphatic ether
1124-1087 strong C-O stretching secondary alcohol
1085-1050 strong C-O stretching primary alcohol
1070-1030 strong S=O stretching sulfoxide
1050-1040 strong, broad CO-O-CO stretching anhydride
1000–650 cm−1
1000–650 cm−1 995-985 strong C=C bending alkene monosubstituted
915-905
980-960 strong C=C bending alkene disubstituted (trans)
895-885 strong C=C bending alkene vinylidene
850-550 strong C-Cl stretching halo compound
840-790 medium C=C bending alkene trisubstituted
730-665 strong C=C bending alkene disubstituted (cis)
690-515 strong C-Br stretching halo compound
600-500 strong C-I stretching halo compound
900–700 cm−1
900–700 cm−1 880 ± 20 strong C-H bending 1,2,4-trisubstituted
810 ± 20
880 ± 20 strong C-H bending 1,3-disubstituted
780 ± 20
(700 ± 20)
810 ± 20 strong C-H bending 1,4-disubstituted or
1,2,3,4-tetrasubstituted
780 ± 20 strong C-H bending 1,2,3-trisubstituted
(700 ± 20)
755 ± 20 strong C-H bending 1,2-disubstituted
750 ± 20 strong C-H bending monosubstituted
700 ± 20 benzene derivative

IR Spectra Table by Compound Class[5]

Compound Class Group Absorption (cm−1) Appearance Comments
acid halide C=O stretching 1815-1785 strong
alcohols O-H stretching 3700-3584 medium, sharp free
O-H stretching 3550-3200 strong, broad intermolecular bonded
O-H stretching 3200-2700 weak, broad intramolecular bonded
O-H bending 1420-1330 medium
aldehyde C-H stretching 2830-2695 medium doublet
C=O stretching 1740-1720 strong
C-H bending 1390-1380 medium
aliphatic ether C-O stretching 1150-1085 strong
aliphatic ketone C=O stretching 1725-1705 strong or cyclohexanone or cyclopentenone
aliphatic primary amine N-H stretching 3400-3300 medium
alkane C-H stretching 3000-2840 medium
C-H bending 1465 medium methylene group
C-H bending 1450 medium methyl group
C-H bending 1385-1380 medium gem dimethyl
C-H stretching 3100-3000 medium
C=C stretching 1678-1668 weak disubstituted (trans)
C=C stretching 1675-1665 weak trisubstituted
C=C stretching 1675-1665 weak tetrasubstituted
C=C stretching 1662-1626 medium disubstituted (cis)
C=C stretching 1658-1648 medium vinylidene
C=C stretching 1648-1638 strong monosubstituted
C=C bending 995-985 strong monosubstituted
C=C bending 980-960 strong disubstituted (trans)
C=C bending 895-885 strong vinylidene
C=C bending 840-790 medium trisubstituted
C=C bending 730-665 strong disubstituted (cis)
alkyl aryl ether C-O stretching 1275-1200 strong
alkyne C-H stretching 3333-3267 strong, sharp
CΞC stretching 2260-2190 weak disubstituted
CΞC stretching 2140-2100 weak monosubstituted
allene C=C=C stretching 2000-1900 medium
amine N-H bending 1650-1580 medium
C-N stretching 1250-1020 medium
amine salt N-H stretching 3000-2800 strong, broad
anhydride C=O stretching 1818 strong
CO-O-CO stretching 1050-1040 strong, broad
aromatic amine C-N stretching 1342-1266 strong
aromatic compound C-H bending 2000-1650 weak overtone
aromatic ester C-O stretching 1310-1250 strong
azide N=N=N stretching 2160-2120 strong
benzene derivative 700 ± 20
carbodiimide N=C=N stretching 2145-2120 strong
carbon dioxide O=C=O stretching 2349 strong
carboxylic acid O-H stretching 3300-2500 strong, broad usually centered on 3000 cm−1
C=O stretching 1760 strong monomer
C=O stretching 1720-1706 strong dimer
O-H bending 1440-1395 medium
conjugated acid C=O stretching 1710-1680 strong dimer
conjugated acid halide C=O stretching 1800-1770 strong
conjugated aldehyde C=O stretching 1710-1685 strong
conjugated alkene C=C stretching 1650-1600 medium
conjugated anhydride C=O stretching 1775 strong
conjugated ketone C=O stretching 1685-1666 strong
cyclic alkene C=C stretching 1650-1566 medium
cyclopentanone C=O stretching 1745 strong
ester C-O stretching 1210-1163 strong
esters C=O stretching 1750-1735 strong 6-membered lactone
fluoro compound C-F stretching 1400-1000 strong
halo compound C-Cl stretching 850-550 strong
C-Br stretching 690-515 strong
C-I stretching 600-500 strong
imine / oxime C=N stretching 1690-1640 medium
isocyanate N=C=O stretching 2275-2250 strong, broad
isothiocyanate N=C=S stretching 2140-1990 strong
ketene C=C=O stretching 2150
ketenimine C=C=N stretching 2000
monosubstituted C-H bending 750 ± 20 strong
nitrile CΞN stretching 2260-2222 weak
nitro compound N-O stretching 1550-1500 strong
none 3330-3250
none 1870-1540
none 1750
none 1720
none 1372-1290
none 1375
none 1370-1365
none 1200-1185
none 1204-1177
none 1195-1168
none 1170-1155
none 1165-1150 hydrate: 1230-1120
none 1160-1120
none 1075-1020
none 1075-1020
none 915-905
none 810 ± 20
none 780 ± 20
none (700 ± 20)
none (700 ± 20)
phenol O-H bending 1390-1310 medium
primary alcohol C-O stretching 1085-1050 strong
primary amide C=O stretching 1690 strong free (associated: 1650)
N-H stretching 3500 medium
secondary alcohol C-O stretching 1124-1087 strong
secondary amide C=O stretching 1680 strong free (associated: 1640)
secondary amine N-H stretching 3350-3310 medium
sulfate S=O stretching 1415-1380 strong
sulfonamide S=O stretching 1370-1335 strong
sulfonate S=O stretching 1372-1335 strong
sulfone S=O stretching 1350-1300 strong
sulfonic acid S=O stretching 1350-1342 strong anhydrous
sulfonyl chloride S=O stretching 1410-1380 strong
sulfoxide S=O stretching 1070-1030 strong
tertiary alcohol C-O stretching 1205-1124 strong
tertiary amide C=O stretching 1680 strong free (associated: 1630)
thiocyanate S-CΞN stretching 2175-2140 strong
thiol S-H stretching 2600-2550 weak
vinyl / phenyl ester C=O stretching 1770-1780 strong
vinyl ether C-O stretching 1225-1200 strong
α,β-unsaturated ester C=O stretching 1730-1715 strong or formates
α,β-unsaturated ketone C=C stretching 1620-1610 strong
δ-lactam C=O stretching 1650 strong γ: 1750-1700 β: 1760-1730
δ-lactone C=O stretching 1750-1735 strong γ: 1770
1,2,3,4-tetrasubstituted
1,2,3-trisubstituted C-H bending 780 ± 20 strong
C-H bending 880 ± 20 strong
1,2-disubstituted C-H bending 755 ± 20 strong
C-H bending 880 ± 20 strong
1,4-disubstituted or C-H bending 810 ± 20 strong

To use an IR spectrum table, first need to find the frequency or compound in the first column, depending on which type of chart that is being used. Then find the corresponding values for absorption, appearance and other attributes. The value for absorption is usually in cm−1.

NOTE: NOT ALL FREQUENCIES HAVE A RELATED COMPOUND.

Applications

Evaluation of Dual - Spectrum IR Spectrogram System on Invasive Ductal Carcinoma (IDC) Breast cancer
Breast Cancer Gross Appearance

Invasive Ductal Carcinoma (IDC) is one of the common types of breast cancer which accounts for 8 out of 10 of all invasive breast cancers. According to the American Cancer Society, more than 180,000 women in the United States find out that they have breast cancers each year, and most are diagnosed with this specific type of cancer.[6] While it is essential to detect breast cancer early to reduce the death rate there may be already more than 10,000,000 cells in breast cancer when it can be observed by x-ray mammograms. however, the IR Spectrum proposed by Szu et al seems to be more promising in detecting breast cancer cells several months ahead of a mammogram. Clinical tests have been carried out with approval of Institutional Review Board of National Taiwan University Hospital. So from August 2007 to June 2008 35 patients aged between (30-66) with an average age of 49 were enlisted in this project. the results established that about 63% of the success rate could be achieved with the cross-sectional data. Therefore the results concluded that breast cancers may be detected more accurately by cross-referencing S1 maps of multiple three-points.[7]

Molecular spectroscopic Methods to Elucidation of Lignin Structure

A Ligninin plant cell is a complex amorphous polymer and it is biosynthesized from three aromatic alcohols, namely P-Coumaryl, Coniferyl, and Sinapyl alcohols. Lignin is a highly branched polymer and accounts for 15-30% by weight of lignocellulosic biomass (LCBM), so the structure of lignin will vary significantly according to the type of LCBM and the composition will depend on the degradation process.[8] This biosynthesis process is mainly consists of radical coupling reactions and it generates a particular lignin polymer in each plant species. So due to having a complex structure, various molecular spectroscopic methods have been applied to resolve the aromatic units and different interunit linkages in lignin from distinct plant species.[9]

General Lignin Structure

References
  1. "Spectrochemical Analysis". Britannica. 23 September 2019. Retrieved 1 May 2021.
  2. Deglr6328 (10 September 2006). "Dichloromethane near IR Spectrum". Wikipedia Commons. Retrieved 29 April 2021.
  3. "The Era of Classical Spectroscopy". MIT Spectroscopy Lab - History. Retrieved 1 May 2021.
  4. "IR spectrum table & chart". Millipore Sigma. Retrieved 29 April 2021.
  5. "IR spectrum table & chart". Millipore Sigma. Retrieved 29 April 2021.
  6. "Invasive Ductal Carcinoma: Diagnosis, Treatment, and More". Breastcancer.org. 21 January 2020. Retrieved 2 May 2020.
  7. Lee, Chuang, Hsieh, Lee, Lee, Shih, Lee, Huang, Chang, Chen, Chia-Yen, Ching-Cheng, Hsin-Yu, Wan-Rou, Ching-Yen, Shyang-Rong, Si-Chen, Chiun-Sheng, Yeun-Chung, Chung-Ming Chen (14 June 2011). EVALUATION OF DUAL-SPECTRUM IR SPECTROGRAM SYSTEM ON INVASIVE DUCTAL CARCINOMA (IDC) BREAST CANCER. Institute of Biomedical Engineering, National Taiwan University, Taiwan. pp. 427–433.{{cite book}}: CS1 maint: location missing publisher (link) CS1 maint: multiple names: authors list (link)
  8. Lu, Lu, Hu, Xie, Wei, Fan, Yao, Yong-Chao, Hong-Qin, Feng-Jin, Xian-Yong, Xing (29 November 2017). "Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods". Journal of Spectroscopy. 2017: 1–15. doi:10.1155/2017/8951658.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. You, Xu, Tingting, Feng (5 October 2016). "Applications of Molecular Spectroscopic Methods to the Elucidation of Lignin Structure". Applications of Molecular Spectroscopy to Current Research in the Chemical and Biological Sciences. doi:10.5772/64581. ISBN 978-953-51-2680-5. Retrieved 1 May 2021. {{cite book}}: |website= ignored (help)CS1 maint: multiple names: authors list (link)
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