Influence of fused aromatic ring on the stability of charge transfer complex between iodine and some five membered heterocyclic molecules through ultrasonic and spectral studies V. Ulagendran, P. Balu, V. Kannappan, R. Kumar, S. Jayakumar Journal of Molecular Structure, 2017 The charge transfer (CT) interaction between two fused heterocyclic compounds with basic pyrrole group as donors, viz., indole (IND) and carbazole (CAR), and iodine (acceptor) in DMSO medium is investigated by ultrasonic and UV–visible spectral methods at 303 K. The formation of CT complex in these systems is established from the trend in acoustical and excess thermo acoustical properties with molar concentration. The frequency acoustic spectra (FAS) is also carried out on these two systems for two fixed concentrations 0.002 M and 0.02 M, and in the frequency range 1 MHz-10 MHz to justify the frequency chosen for ultrasonic study. The absorption coefficient values in solution are computed and discussed. The formation constants of these complexes are determined using Kannappan equation in ultrasonic method. The formation of 1:1 complexes between iodine and IND, CAR was established by the theory of Benesi – Hildebrand in the UV–visible spectroscopic method. The stability constants of the CT complexes determined by spectroscopic and ultrasonic methods show a similar trend. These values also indicate that the presence of fused aromatic ring influences significantly when compared with K values of similar CT complexes of parent five membered heterocyclic compound (pyrrole) reported by us earlier.
Molecular interaction studies of cinnamaldehyde with certain alcohols by ultrasonic method at 303.15 K Indian Journal of Pure and Applied Physics, 2012
Thermo acoustic and spectral investigations of charge transfer interaction between aromatic amine and ketones R. Kumar, V. Ulagendran, V. Kannappan, S. Jayakumar Fluid Phase Equilibria, 2011 Ultrasonic velocity (u), density (ρ) and coefficient of viscosity (η) were measured for ternary mixtures containing aniline (ANI) as common component and acetophenone (ACP), 4-chloroactophenone (ClACP) and 4-methylacetophenone (MACP) as other components in n-hexane medium in the concentration range 0.025–0.2 M. The measurements were made at four different temperatures, namely, 293, 298, 303 and 308 K and at atmospheric pressure. The experimental results have been used to calculate various acoustical parameters and excess parameters. The trend in these parameters with concentration establishes that (i) strong intermolecular interactions exist in these mixtures and (ii) formation of charge transfer complexes through hydrogen bonding between primary amine and aromatic ketones. The formation of complexes has also been confirmed by optical spectroscopy at 303 K. The formation constants of the charge transfer complexes determined using Benesi–Hildebrand equation (spectroscopic method) are comparable with those obtained using Kannappan equation (ultrasonic method). It is observed that the stability of the complexes is influenced by the structure of the component molecules. In order to assess the thermodynamic stability of the complexes, free energy of formation (ΔG), enthalpy of formation (ΔH) and entropy changes (ΔS) are computed.
Ultrasonic and optical studies on charge transfer complexes of p-chloranil with certain aromatic hydrocarbons in DMSO at 303.15 K R. Kumar, G. Padmanabhan, V. Ulagendran, V. Kannappan, S. Jayakumar Journal of Molecular Liquids, 2011 Ultrasonic investigation has been carried out on six ternary systems to establish the complex formation between p-chloranil (acceptor) and six aromatic hydrocarbons (donors), namely, benzene, toluene, o-xylene, m-xylene, p-xylene and mesitylene in DMSO medium at 303.15 K and at atmospheric pressure. Studies were carried out in the concentration range of 0.002 to 0.02 M of acceptor and donor with equimolar concentration of the two components in solution. The trend in the acoustical parameters and magnitude of excess thermo acoustical parameters has been used to identify the existence of strong intermolecular interaction through charge transfer complex formation. The formation of 1:1 complex was also confirmed by UV–Visible spectroscopic method at 303.15 K in these systems. It may be pointed out that the formation constants of the charge transfer complexes determined by Benesi–Hildebrand (spectroscopic) and Kannappan (ultrasonic) methods show similar trend and well establish the influence of structural aspect of the donor aromatic compounds on the stability of charge transfer complexes.
Ultrasonic and spectroscopic investigations of charge-transfer complexes in ternary liquid mixtures V. Ulagendran, R. Kumar, S. Jayakumar, V. Kannappan Journal of Molecular Liquids, 2009 Charge-transfer complexes formed between iodine ( σ -acceptor) and pyrrole, thiophene and pyridine ( π as well as n-electron donors) have been studied spectrophotometric and ultrasonic techniques at 303.15 K in dimethyl sulphoxide medium. The measured values of ultrasonic velocity, density and viscosity and the derived acoustical parameters such as adiabatic compressibility ( κ ), free length ( L f ), internal pressure ( π i ), molar volume ( V m ) and available volume ( V a ) have been used to study the molecular interactions and the complexes of heterocyclic aromatic compounds. The excess thermodynamic parameters like excess velocity ( u E ), excess adiabatic compressibility ( κ E ), excess free length ( L f E ), excess molar volume ( V m E ) and excess available volume ( V a E ) have been computed and the sign and magnitude of these parameters indicate the strength of interactions and the formation of charge-transfer complex. The formation constants of the charge-transfer complexes were determined by the Benesi–Hildebrand equations (optical method) and compared with those obtained from Kannappan method (ultrasonic method). The formation constants of complexes of iodine with aromatic compounds depend on the structure of the donor and acceptor molecules.
