INFRARED SPECTROSCOPIC ANALYSIS OF COMPLEXATION BETWEEN 5-AMINO ISO-PHTHALIC ACID, COBALT NITRATE, AND ETHYLENEDIAMINE

ETHYLENEDIAMINE

Toirova Gulshoda

Doctoral student of Inorganic Chemistry, Termez State University

Khayit Turayev

Professor, Department of Analytical Chemistry, Termez State University

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. 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): 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.