Saminathan Ratnapandian

Wavelength (cm^-1)	Bonds	Wavelength (cm^-1)
Bonds
3400–3100	vO-H glycosidic groups	1400–1050	Complex vC-O vibrations
1606	C=C aromatic ring	1280	-OH aromatic
1566	Aromatic ring stretch	1111	-C-OH alcohol
1516	C-H alkanes	1035	C-O alcohol
1445	C-O alcohol	767	C-H alkenes

3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800
Wavelength (cm^-1)

Figure 3.10 FTIR spectra of dyes

The two dyes under investigation were individually made to react with the chosen mordants (copper (II) sulfate and iron (II) sulfate). Figure 3.11 and Figure 3.12 show the spectra for the complexes formed from the above reaction. A lower difference is observed between the spectra for complexes resulting from the different dyes reacted with the same mordant. This may be due to a general suppression of aromatic ring stretch at a wavelength of 1566. However, the C-O vibrations identified in the wavelength range of 1050–1400 are not changed.



^4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800
Wavelength (cm^-1)

Figure 3.11 FTIR spectra of complexes formed by the two dyes in combination with copper

Caspian-iron

Transmis₃s₃i₇o₇n_.9(%₉ )


Thar-iron
1607.18


1364.15
1027.95
667.95

1606.63

3397.42


1082.93
1040.13


667.93

3700.03400 3000 2600 2200 1900 1700 1500 1300 1100 900 700

1
Wavelength (cm^-1)

Figure 3.12 FTIR spectra of complexes formed by the two dyes in combination with iron

The spectra of the dyed fabric become near identical, as can be seen in Figure 3.13 and

3.14. Hence it may be inferred that in a textile matrix (cotton fabric), the bond-

geometry becomes restricted as compared to the dye-mordant by itself. The mordant continues to govern the bonds present in the final complex formed for the dyes under consideration. As for iron, the bond angles and orientation are apparently identical for both dyes, resulting in the observed similarity in shade (reflectance curve). On the other hand, although copper forms the same bonds, there is a different orientation for each of the dyes, giving rise to the divergence in shade. The detection and confirmation of these subtle variations by 2D-IR spectroscopy, as suggested by Khalil et al. [141] and Noda [142], is beyond the scope of this thesis and hence recommended for future work.

4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800

Wavelength (cm^-1)
Figure 3.13 FTIR spectra of cotton fabric dyed in combination with copper as mordant
Caspian-iron-cotton
3330.69 _1610.84