Asian Journal of Research in Chemistry

Neeti Singh ¹, Afaq Ahmad ¹

Affiliations
1 Department of Chemistry, Faculty of Science, Aligarh Muslim University, Aligarh -202002, IN

Abstract

The charge transfer complexes of the donor benzamide (BZ) with &#960;-acceptor picric acid (PA) have been studied spectrophotometrically in various solvents such as carbon tetra chloride, ethanol, and methanol at room temperature using absorption spectrophotometer. The results indicate that formation of CTC in less polar solvent is high. The stoichiometry of the CT complex was found to be 1:1. The physical parameters of CT complex were evaluated by the Benesi-Hildebrand equation. The data are discussed in terms of formation constant (KCT), molar extinction coefficient (&#948;CT), standard free energy (G o ), oscillator strength(ƒ), transition dipole moment (&#181;EN), resonance energy (RN) and ionization potential (ID). The results indicate that the formation constant (K<SUB>CT</SUB>) for the complex were shown to be dependent upon the nature of electron acceptor, donor and polarity of solvents which were used. The results show that a charge transfer molecular complex between picric acid and benzamide stabilized by hydrogen bonding. The formation of the complex has been confirmed by UV-visible, FT-IR, 1 H-NMR, TGA/DTA spectral data methods. On the basis of the studies, the structure of CT complex is [(BZ) + (PA) −] , and a general mechanism for its formation is proposed.

Keywords

Charge Transfer complex, Benzamide (BZ), Picric acid (PA), UV-visible, FT-IR, ¹H–NMR, TGA/DTA

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Neeti Singh ¹, Ishaat M. Khan ¹, Afaq Ahmad ¹

Affiliations
1 Department of Chemistry, Aligarh Muslim University, Aligarh-202002, IN

Abstract

Charge transfer complexes of picric acid, with m-nitroaniline, were investigated by spectrophotometric method in three different organic solvents viz-acetone, ethanol, and methanol. The data are discussed in terms of association constant, (K_CT) and molar extinction coefficient (ε_CT), standard free energy (ΔG^°), oscillator strength (ƒ), and transition dipole moment (μ_EN) were calculated. The spectrum obtained form the complex of picric acid and m-nitroaniline shows absorption bands at 450 nm for methanol, 445 nm for ethanol and 440 nm for acetone. The results reveal that the interaction between the donor and acceptor is due to π-π* transitions. The stiochiometry of the complexes was found to be in the ratio of 1:1 by straight line method. The influences of used solvents such as acetone, ethanol, and methanol, on spectroscopic parameters were investigated. The ionization potential (I_D) of the donor was also determined.

Keywords

Charge Transfer Complex, M-Nitroaniline (MNA), Picric Acid (PiOH), Visible Region, Formation Constant, FTIR Spectroscopy.

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