ISSN (E): 2181-4570 ResearchBib Impact Factor: 6,4 / 2024 SJIF 2024 = 5.073/Volume-2, Issue-12
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INFRARED SPECTROSCOPIC ANALYSIS OF COMPLEXATION BETWEEN
5-AMINO ISO-PHTHALIC ACID, COBALT NITRATE, AND
ETHYLENEDIAMINE
Toirova Gulshoda
Doctoral student of Inorganic Chemistry, Termez State University
https://orcid.org/0009-0005-6412-3389
Khayit Turayev
Professor, Department of Analytical Chemistry, Termez State University
https://orcid.org/0000-0002-0627-5449
Abstract
This study investigates the complexation process between 5-amino iso-phthalic
acid (IPA), cobalt nitrate, and ethylenediamine (EDA) using Fourier-transform infrared
(FTIR) spectroscopy. The observed vibrational shifts in the spectrum provide evidence of
functional group coordination and the formation of a stable metal-ligand complex. The
results demonstrate changes in the vibrational frequencies of carboxylate, amino, and
cobalt-related bonds, confirming structural modifications during the interaction.
Keywords:
cobalt nitrate, acid,
Introduction
5-Amino iso-phthalic acid is an aromatic dicarboxylic acid with applications in
polymers, dyes, and pharmaceuticals due to its ability to coordinate with metals. Cobalt
nitrate, a commonly used transition metal salt, forms coordination complexes with various
ligands. Ethylenediamine (EDA), a bidentate ligand, effectively stabilizes metal
complexes due to its dual coordination sites. This study aims to analyze the structural and
vibrational changes during the formation of a coordination complex between IPA, cobalt
nitrate, and EDA using FTIR spectroscopy.
Materials and Methods
Materials:5-amino iso-phthalic acid (purity > 99%), cobalt nitrate hexahydrate, and
ethylenediamine were purchased and used without further purification.
ISSN (E): 2181-4570 ResearchBib Impact Factor: 6,4 / 2024 SJIF 2024 = 5.073/Volume-2, Issue-12
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Synthesis of the Complex: Equimolar solutions of 5-amino iso-phthalic acid and cobalt
nitrate were mixed and stirred at room temperature. Ethylenediamine was gradually added
to the solution until a homogeneous mixture was achieved. The reaction was carried out
at [specific temperature and duration]. The precipitate was filtered, washed, and dried
under vacuum.
FTIR Spectroscopy:The IR spectra of the pure compounds and the synthesized complex
were recorded using a [spectrometer model] in the range of 400–4000 cm⁻¹ with a
resolution of 4 cm⁻¹.
Results and Discussion.
Complex Formation:
The spectral changes strongly support the formation of a
coordination complex between IPA, cobalt nitrate, and EDA. The results suggest that both
carboxylate groups and ethylenediamine coordinate with cobalt, forming a stable
complex.
FTIR Spectrum Analysis
The FTIR spectrum of the synthesized complex (shown in the figure) reveals significant
shifts and the appearance of new peaks, confirming the formation of a coordination
complex. The main observations are as follows:
1. Broad Peak at 3253–3095 cm⁻¹:
This region corresponds to O-H and N-H stretching vibrations. The broadening and
intensity changes indicate the involvement of hydroxyl and amine groups in coordination.
2. Shift in Carbonyl Stretching (C=O):
ISSN (E): 2181-4570 ResearchBib Impact Factor: 6,4 / 2024 SJIF 2024 = 5.073/Volume-2, Issue-12
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The carbonyl stretching vibration of IPA shifted from 1700 cm⁻¹ (in free IPA) to 1689
cm⁻¹ in the complex, suggesting coordination of carboxylate groups with cobalt ions. This
is further supported by the emergence of new peaks at 500–600 cm⁻¹, indicative of Co-O
bonds.
3. EDA Involvement:
N-H stretching vibrations of EDA exhibited a shift, confirming coordination through
nitrogen atoms. Deformation vibrations in the 1258–1300 cm⁻¹ range further support
EDA's role in stabilizing the complex.
4. New Peaks in the Metal-Ligand Region:
Peaks at 505–589 cm⁻¹ represent Co-O and Co-N bonds, confirming the formation of a
coordination network between cobalt, IPA, and EDA.
5. Other Key Vibrations:
Peaks at 1440–1258 cm⁻¹ correspond to aromatic C=C stretching and confirm the
preservation of the aromatic backbone in the complex. Additional peaks at 933–797 cm⁻¹
are attributed to out-of-plane vibrations, indicative of structural reorganization.
Conclusion
Infrared spectroscopic analysis confirms the formation of a coordination complex between
5-amino iso-phthalic acid, cobalt nitrate, and ethylenediamine. The shifts in vibrational
frequencies of carboxylate, amine, and metal-oxygen bonds demonstrate significant
structural and electronic interactions during complexation.
References
1. Smith, J., & Brown, T. (2020). Applications of Aromatic Dicarboxylic Acids in
Materials Chemistry. Journal of Organic Chemistry, 85(4), 567–578.
2. Kumar, S., & Gupta, R. (2019). Bidentate Ligands and Their Coordination Chemistry.
Inorganic Chemistry, 58(12), 2930–2941.
3. Lee, H. J., et al. (2022). Structural Characterization of Metal-Ethylenediamine
Complexes. Journal of Coordination Chemistry, 65(6), 789–800.
