The spectroscopic methods of the different regions of the Electromagnetic spectrum are the most powerful and useful techniques available for the understanding of molecular structure, nature of bonding between atoms, confirmation analysis, symmetry of molecules, ions in crystals and so forth. The high resolution IR spectroscopic studies have recently received a great thrust due to the advent of advanced Fourier transform spectrometers. In the present investigation the spectral changes are studied in the vibrational spectra of thiourea, thiosemi carbazide in non aqueous solvent. The H2N stretching vibrations observed at 3371cm¯¹, 3259cm¯¹, & 3156cm¯¹ indicated that 3 different types of NH2 groups arising out of tautomeric form. The results obtained from the present study confirm that the solute – solvent interactions occurring in the solution is through intermolecular H- bonding.

1. IOSR Journal of Applied Physics (IOSR-JAP)
e-ISSN: 2278-4861.Volume 4, Issue 1 (May. - Jun. 2013), PP 05-08
www.iosrjournals.org
www.iosrjournals.org 5 | Page
Spectroscopic study on Thiourea and Thiosemicarbazide in Non-
aqueous media
Ragamathunnisa .M1
, Jasmine Vasantha Rani.E2
, Padmavathy R2
, Radha N3
1
(Government Arts College for Women, Department of Physics, Pudukkottai, Tamilnadu, India)
2
(Seethalakshmi Ramaswamy College, Department of Physics, Trichy Tamilnadu, India)
3
(Seethalakshmi Ramaswamy College, Department of chemistry, Trichy Tamilnadu, India)
Abstract: The spectroscopic methods of the different regions of the Electromagnetic spectrum are the most
powerful and useful techniques available for the understanding of molecular structure, nature of bonding
between atoms, confirmation analysis, symmetry of molecules, ions in crystals and so forth. The high resolution
IR spectroscopic studies have recently received a great thrust due to the advent of advanced Fourier transform
spectrometers. In the present investigation the spectral changes are studied in the vibrational spectra of
thiourea, thiosemi carbazide in non aqueous solvent. The H2N stretching vibrations observed at 3371cm¯¹,
3259cm¯¹, & 3156cm¯¹ indicated that 3 different types of NH2 groups arising out of tautomeric form. The
results obtained from the present study confirm that the solute – solvent interactions occurring in the solution is
through intermolecular H- bonding.
Keywords – Dimeric structure, Hydrogen bonding, Thiosemicarbazide, Thiourea.
I. Introduction
Progress in the area of non-linear optics (NLO) depends upon the development of new
materials. When compared with the inorganic materials, organic and materials are attracting a great deal of
attention, as they have large optical susceptibilities, inherent ultra fast response time and good optical properties
[1-3]. The advent of the instrumental methods like infrared has now made the task of an organic chemist
comparatively simpler [4] although the IR spectrum is characteristic of the entire molecule. Fourier transform
Infrared Spectrometry (FTIR) has been extensively developed over the past decade and provides a number of
advantages. The Organo sulfur compounds have variety of applications in industries. It is mainly used in textile
processing [5] and also in the reductive work up of Ozonolysis [6] to give carbonyl compound. They are also
used as building blocks to pyrimidine derivatives. Thiourea condenses with β-dicarbonyl compounds [7].
Thiourea is a reagent in organic synthesis to pharmaceuticals like thiobarbituric acid and sulfathiazole.
Thiosemicarbozide has been shown to be good ligand for range of metals, including zinc, mercury, cadmium
and nickel [8,9] Thiosemicarbazide is a thiourea derivative. It is used in the preparation of antibacterial
compounds. In the present investigation the FTIR spectral studies are carried out in non – aqueous solutions of
thiourea(Thiourea solvated in formamide) & thiosemicarbazide (Thiosemicarbazide in formamide) in order to
probe the effect of H – bonding in the solvation process.
II. Experimental Technique
Thiourea & Thio semicarbazide (AR Merc) were used in non - aqueous medium. Solutions
of saturation molalities were prepared by weighing in electronic balance and an accuracy of (0.001gm) were
stored in vaccum decicator until use. The Fourier transform infrared was carried out between 4000cm¯¹ to
400cm¯¹ by recording the spectrum using PERKIN ELMER SPECTRUM RXI spectrometer.
III. Results And Discussion
1.1 FTIR Study – THIOUREA (TU)
The spectrum of formamide (solvent) and thiourea(solute) is shown in fig. (1) and (2).The
observed frequencies are tabulated. In the spectrum of thiourea, the vibrations found at 3371cm-
¹, 3260cm-
¹, &
3156cm-
¹ indicate that the three different types of NH2groups arising out of tautomeric form. The peaks at
2684cm-
¹, 2354 cm-
¹ besides small shoulders upto 2100 cm-
¹ are indicative of ammonium & iminium salt like
structure. A sharp peak at 1585 cm-
¹arises due to thioamide (C=S) asymmetric stretching vibration while the
symmetric vibrations may be located at 1449 cm-
¹. A broad band at 1088 cm-
¹ is due to C-S vibrations. The
sharp peak at 729 cm-
¹ is assigned to the S-H bending vibration. C-N bending vibration and NH bending
vibration found at 627 cm-
¹ and at 493 cm-
¹ respectively.

2. Spectroscopic study on Thiourea and Thiosemicarbazide in Non-aqueous media
www.iosrjournals.org 6 | Page
1.2 FTIR- THE SOLUTION OF THIOUREA IN FORMAMIDE:
The solution spectrum is shown in fig. (3) In the solution the solvent peak at 3416cm-1
has shifted to
3372cm-1
towards lower energy side by 44 cm-1
. Besides a series of stretching vibrations are observed at
3267cm-1
,3163cm-1
,2888 cm-1
,2688cm-1
and at 2204 cm-1
.These vibration frequencies are confirmed the
presence of both the solute [NH] and solvent peaks [CH] and [C=NH]. The sharp peak of bands at 1697cm¬¹
and 1550 cm¬¹ in the solvent spectrum have disappeared and a new band occurs at1598 cm¬¹ . This peak
has arisen due to H- bonding between >C=O of solvent and NH2 of solute destroying the dimeric structure of
pure solvent. The >C=S vibration at 1584 cm¬¹ is shifted to higher energy by 14 cm¬¹. A higher energy shift of
10 cm¬¹ occurs at 1399 cm¬¹ peak and dramatic change in this band region may be attributed to solute- solvent
interaction in >C=N-H site. A new peak arises at 1077 cm¬¹ due to C-S stretching mode of the solute. The 729
cm¬¹ 627 cm¬¹ are due to bending vibrations of the solute shifted to lower energy region of the solution
compared to the salt spectrum. In this region the 494 cm¬¹ has shifted to higher energy region by 1 cm¬¹. All
these spectral changes may be due to the H-bonding pattern which shown below
1.3 FTIR - THIOSEMI CARBAZIDE (TSC)
The salt spectrum of TSC is shown in fig. (4) The series of vibrations in the region 3365 cm-1
to 3169
cm-1
are due to different types of NH2 and NH groups. The absorption frequencies found at 1616 cm-1
and 1516
cm-1
are due to >C=S-NH functional groups. ie. asymmetric and symmetric stretching vibrations of thio amide I
& II bands. At 1273 cm-1
& 1155 cm-1
C=N bending and C-S stretching vibrations occur. The C-S, NH2 and NH
bending vibrations are found at 993 cm-1
,792 cm-1
,649 cm-1
and 576 cm-1
respectively.
1.4 FTIR - THIOSEMICARBAZIDE IN FORMAMIDE (TSC)
The solution spectrum of TSC in formamide is shown in fig. (5), which is similar to the solvent rather
than to the salt. This indicates the predominant amount of formamide compared to solute molecules. A lower
energy shift of 3400 cm¬¹ band by 16 cm¬¹ is observed. It is due to the weakening of C=O-NH bonds in the
solvent. Broadening of this peak which is quite smooth may be due to the binding of NH of formamide to
another group in the solute. The four small shoulders like peaks in the region 2407 cm¬¹ to 2064 cm¬¹ have
become well defined in the solution spectra indicating the presence of strong solute – solvent interactions. A
broad peak centered at 1619 cm¬¹ encompasses both the amide I of formamide and thioamide I band of TSC.
The intense peak is characteristics of strong solute - solvent interaction at >C=O & >C=S groups. This peak has
shifted to lower energy region by 79 cm¬¹ indicating >C-O more single bond character during donar – acceptor
interaction. Similarly the amide II vibration has also shifted to lower energy by 22 cm¬¹ indicating lengthening
of bonds. At 997 cm¬¹, 787cm¬¹, the solute vibrations are observed. The former is higher energy shift by 3.6
cm¬¹, while the later peak is lower energy shift by 4.5 cm¬¹ which is the indication of strong binding. The solute
– solvent interaction through inter molecular H bonding are given below.

3. Spectroscopic study on Thiourea and Thiosemicarbazide in Non-aqueous media
www.iosrjournals.org 7 | Page
Fig.1 FTIR Spectrum of Formamide
FTIR SPECTRUM
ACIC
St.Joseph's College ( Autonomous )
Trichy-2
Spectrum Name: SALT-III.sp
Date: 6/20/2011
SALT-III.pk
SALT-III.sp 3601 4000.00 400.00 5.42 99.31 4.00 %T 5 0.50
REF 4000 99.13 2000 45.24 600
3941.31 96.77 3811.95 92.03 3729.24 91.71 3371.07 13.64 3259.83 11.95
3156.17 8.82 2684.03 18.99 2354.31 31.65 1584.77 5.42 1449.28 6.21
1088.47 13.46 728.77 64.01 626.69 64.48 493.90 17.95
4000.0 3000 2000 1500 1000 400.0
0.0
10
20
30
40
50
60
70
80
90
100.0
cm-1
%T
3941.31
3811.95 3729.24
3371.07
3259.83
3156.17
2684.03
2354.31
1584.771449.28
1088.47
728.77
626.69
493.90
FTIR SPECTRUM
ACIC
St.Joseph's College ( Autonomous )
Trichy-2
Spectrum Name: -For + Salt-III.sp
Date: 6/16/2011
-For + Salt-III.pk
-FOR_S~2.SP 3601 4000.00 400.00 6.52 100.00 4.00 %T 5 1.00
REF 4000 99.51 2000 90.30 600
3912.94 95.63 3792.63 91.08 3372.76 6.52 3266.71 7.19 3163.03 6.84
2888.03 20.38 2688.31 42.02 2204.99 73.64 1598.32 13.47 1399.42 16.81
1076.78 37.49 725.72 68.60 623.82 58.38 494.39 36.12
4000.0 3000 2000 1500 1000 400.0
0.0
10
20
30
40
50
60
70
80
90
100.0
cm-1
%T
3912.94
3792.63
3372.76
3266.71
3163.03
2888.03
2688.31
2204.99
1598.32
1399.42
1076.78
725.72
623.82
494.39
Fig.2 FTIR Spectrum of Thiourea Fig.3 FTIR Spectrum of Thiourea in Formamide
FTIR SPECTRUM
ACIC
St.Joseph's College ( Autonomous )
Trichy-2
Spectrum Name: SALT-II.sp
Date: 6/20/2011
SALT-II.pk
SALT-II.sp 3601 4000.00 400.00 6.38 98.96 4.00 %T 5 0.50
REF 4000 98.59 2000 49.04 600
3944.86 95.81 3854.13 94.82 3723.11 95.09 3365.51 10.58 3169.84 6.38
2062.39 37.11 1616.38 9.51 1516.67 17.69 1273.68 29.17 1155.59 35.22
993.91 26.81 792.33 45.01 649.84 49.46 576.51 29.10
4000.0 3000 2000 1500 1000 400.0
0.0
10
20
30
40
50
60
70
80
90
100.0
cm-1
%T
3944.86
3854.13
3723.11
3365.51
3169.84
2062.39
1616.38
1516.67
1273.68
1155.59
993.91
792.33
649.84
576.51
FTIR SPECTRUM
ACIC
St.Joseph's College ( Autonomous )
Trichy-2
Spectrum Name: -For + Salt-II.sp
Date: 6/16/2011
-For + Salt-II.pk
-FOR_S~1.SP 3601 4000.00 400.00 6.44 99.69 4.00 %T 5 1.00
REF 4000 99.68 2000 93.15 600
3969.81 97.87 3781.45 96.78 3174.69 6.44 2886.36 18.49 2773.04 44.10
2407.81 79.57 2198.78 83.32 2064.09 82.11 1618.96 8.92 1528.02 34.07
1390.55 21.00 1304.33 13.73 1167.11 44.41 1060.12 57.33 997.53 56.65
787.69 40.72 589.66 13.31
4000.0 3000 2000 1500 1000 400.0
0.0
10
20
30
40
50
60
70
80
90
100.0
cm-1
%T
3969.81
3781.45
3174.69
2886.36
2773.04
2407.81
2198.78
2064.09
1618.96
1528.02
1390.55
1304.33
1167.11
1060.12
997.53
787.69
589.66
Fig.4 FTIR Spectrum of Thiosemicarbazide Fig.5 FTIR Spectrum of Thiosemicarbazide
in Formamide
-
-
4000.0 3000 2000 1500 1000 400.0
0.0
10
20
30
40
50
60
70
80
90
100.0
cm-1
%T
3884.30
3779.14
3416.14
2887.69
2772.25
2400.54
2288.05
2197.54
1697.00
1389.74
1308.86
1054.09
602.52

4. Spectroscopic study on Thiourea and Thiosemicarbazide in Non-aqueous media
www.iosrjournals.org 8 | Page
TABLE - 1 A comparative study of FTIR spectral results
Wave Number cm-1
Band
Assignment
Formamide Thio urea Thio urea with
Formamide
TSC TSC with
Formamide
νNH 3416 3371 3372 3366 3400(sh)
νCH 2888
2772
2600 – 2500(sh)
2400
3260
3156
2684
2354
3267
3163
2888
2688
3169
2400–
2300(sh)
2062(sh)
2886
2773
2600(sh)
2408
νC=N 2288
2197
2100
1700 –
2205
1598
1616
1517
2300-2200(sh)
1618
νC=S 1697 1600(sh) 1377 1356(sh) 1528
νC-S 1550(sh)
1390,1309
1054
1584
1449
1088
1400–
1300(sh)
726
1273
993
792
1391
1304
1060
νCH 603 729
627
494
624
494
650
577
997
787
590
IV. Conclusion
From this spectral analysis various functional groups are identified. The dimeric structure of
formamide is changed due to solvation with thiourea. Strong solute-solvent interaction occurs in TSC with
formamide. This study also confirmed that the solute- solvent interactions occurring in the solutions is through
intermolecular H-bonding.
Acknowledgement
Authors acknowledge the immense help received from the scholars whose articles are citied and
included in references of this manuscript. The authors also grateful to authors/editors/publishers of all those
articles, journals and books from where the literature for this article has been reviewed and discussed.
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