Kannappan Venu | University of Madras (original) (raw)

Papers by Kannappan Venu

Research paper thumbnail of Ultrasonic and Spectral Studies on Hydrogen Bonded Complexes of Aromatic Aldehydes and N-Methylaniline in n-Hexane

Journal of Applied Solution Chemistry and Modeling

Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-m... more Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-methylaniline (NMANI) and three structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde(SA) in n-hexane medium at 303.15 K and at atmospheric pressure. Acoustical parameters are computed from the measured values of ultrasonic velocity, density and dynamic viscosity. The variation of acoustical parameters in the concentration range investigated establishes complex formation through intermolecular hydrogen bonding between aldehyde and N-methylaniline. The existence of strong aldehyde-amine interaction is also confirmed through the recorded UV-Visible absorption spectra with Benesi-Hildebrand theory at 303.15 K. The formation constants of the hydrogen bonded complexes are determined by spectroscopic and ultrasonic methods and compared. These values computed by two different methods are comparable and follow similar trend. The trend in the formation constants is discussed based on structures of the component molecules and correlate with computed molecular properties.

Research paper thumbnail of Ultrasonic and Spectral Studies on Hydrogen Bonded Complexes of Aromatic Aldehydes and N-Methylaniline in n-Hexane

Journal of Applied Solution Chemistry and Modeling, 2013

Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-m... more Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-methylaniline (NMANI) and three structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde(SA) in n-hexane medium at 303.15 K and at atmospheric pressure. Acoustical parameters are computed from the measured values of ultrasonic velocity, density and dynamic viscosity. The variation of acoustical parameters in the concentration range investigated establishes complex formation through intermolecular hydrogen bonding between aldehyde and N-methylaniline. The existence of strong aldehyde-amine interaction is also confirmed through the recorded UV-Visible absorption spectra with Benesi-Hildebrand theory at 303.15 K. The formation constants of the hydrogen bonded complexes are determined by spectroscopic and ultrasonic methods and compared. These values computed by two different methods are comparable and follow similar trend. The trend in the formation constants is discussed based on structures of the component molecules and correlate with computed molecular properties.

Research paper thumbnail of Spectroscopic Characterization and Electronic Structure Analysis of Linagliptin by DFT Method

NIScPR-CSIR, India, Sep 1, 2021

Введение. Рынки труда регионов Арктической зоны Российской Федерации испытывают потребность в кад... more Введение. Рынки труда регионов Арктической зоны Российской Федерации испытывают потребность в кадрах, которым предстоит работать в экстремальных условиях крайнего Севера. Это объективное обстоятельство накладывает особенные, зачастую, повышенные требования к квалификации и уровню подготовки соискателей работы, в том числе, и к качеству их образования. Актуальность данного исследования обуславливается набирающей популярность формой онлайн-обучения, которой свойственны как достоинства, связанные с доступностью такого образования и его безопасностью в эпоху пандемии, так и недостатки, связанные с качеством получаемого образования. Цель исследования-анализ востребованности специалистов, получивших профессиональное образование в дистанционной онлайн-форме, на рынке труда регионов Арктической зоны Российской Федерации. Материалы и методы. Информационной базой исследования послужили результаты опроса более 2200 работодателей из территорий всех 9 субъектов Российской Федерации, входящих в Арктическую зону. Опросы проводились методами онлайн анкетирования. При обработке результатов опроса использовались методы описательной статистики, системного анализа и сравнительный анализ данных. Результаты исследования. Применимость практики получения профессионального образования в онлайн-форме для условий Арктической зоны одобряют 58% опрошенных работодателей, а 42% относятся к этому отрицательно. Только каждый третий опрошенный работодатель считает существующую в АЗ РФ систему онлайн-образования в целом соответствующей их требованиям к такому типу подготовки. При этом чуть более 40% работодателей всех арктических регионов выразили готовность принять в штат специалистов с дипломом об онлайн-образовании. Результаты опроса, представленные в разрезе арктических регионов и видов экономической деятельности, показали неоднородное отношение работодателей к исследуемым вопросам. Обсуждение и заключение. Полученные результаты подтвердили значимость для работодателей АЗ РФ вопросов подготовки кадров с применением онлайн-обучения, которое обладает как рядом несомненных преимуществ для арктических территорий, так и ограничений. Важным направлением развития исследования является оценка возможностей существующей системы дистанционного онлайн-образования с позиции самих субъектов образования-вузов и колледжей, расположенных в Арктической зоне России.

Research paper thumbnail of Ultrasonic, spectrophotometric and theoretical studies of sigma and PI interactions of iodine with substituted benzene

RSC Advances, 2015

The acoustical method shows the ability to study the structure, energetics and spectroscopic aspe... more The acoustical method shows the ability to study the structure, energetics and spectroscopic aspects of charge transfer complexes of three different benzenoid compounds with iodine and is supported by the UV-Visible and DFT methods.

Research paper thumbnail of Studies on free energies of solution and its components of thiazole amine derivatives

Journal of Molecular Liquids, 2012

Abstract The polarizable continuum model (PCM) is employed to investigate theoretically the solva... more Abstract The polarizable continuum model (PCM) is employed to investigate theoretically the solvation of two heterocyclic compounds containing halogens. The PCM analysis has been carried out for 4-(4-chlorophenyl)-1,3-thiazol-2-amine and 4-(4-bromophenyl)-1,3-thiazol-2-amine in ten solvents with wide range of dielectric constants. In this paper, we report the results obtained in the computation of electrostatic interaction, repulsive component of Gibb's free energy of solvation, cavitation enthalpy and entropy of solvation for the two thiazole amines in various solvents. The dipole moments of the two amine molecules are calculated theoretically by AM1, PM3, MNDO and ab initio methods. The induced dipole moments of these two thiazoles are also calculated in these solvents. The thermodynamic properties of the systems, such as free energies, electrostatic interaction, cavitation enthalpy and dipole moment are discussed in terms of the physical properties such as dielectric constant, index of refraction, surface tension and molecular size of the solvents.

Research paper thumbnail of Studies on nano suspensions of silver sol and redispersed nanocrystallite silver in aqueous and alcoholic media

Journal of Molecular Liquids, 2011

Nanocrystallite silver and silver sol were prepared and characterized by UV-visible spectra, XRD,... more Nanocrystallite silver and silver sol were prepared and characterized by UV-visible spectra, XRD, TEM and HRTEM. The crystallite silver is re-dispersed in two different media, namely, water and alcohol and sonicated before ultrasonic investigation. The silver sol was used as such. Three different models for the propagation of ultrasound through two phase media are compared in these three different types of nano suspensions. Effect of particle size and medium on ultrasonic velocity (U), compressibility (κ) impedance (Z) and viscous relaxation time (τ) is studied. The particle concentration range was 0.2-1 v/v. Density and viscosity of the dispersion and sol are measured at different particle volume fractions. Effective density and ultrasonic velocity are computed by Urick, Kuster and Toksöz and Urick and Ament models and compared with experimental velocities. Values of effective density obtained by using Urick and Urick and Ament equations closely agree with experimental results of density while Urick's equation prediction of velocity is in close agreement with the experimental velocities. This comes as a surprise in view of the large density difference between the medium and suspended particle and suggests the possibility of the balancing effect of the inertial and viscous forces operating in the suspension.

Research paper thumbnail of Ultrasonic and Spectral Studies on Hydrogen Bonded Complexes of Aromatic Aldehydes and N-Methylaniline in n-Hexane

Journal of Applied Solution Chemistry and Modeling, 2013

Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-m... more Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-methylaniline (NMANI) and three structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde(SA) in n-hexane medium at 303.15 K and at atmospheric pressure. Acoustical parameters are computed from the measured values of ultrasonic velocity, density and dynamic viscosity. The variation of acoustical parameters in the concentration range investigated establishes complex formation through intermolecular hydrogen bonding between aldehyde and N-methylaniline. The existence of strong aldehyde-amine interaction is also confirmed through the recorded UV-Visible absorption spectra with Benesi-Hildebrand theory at 303.15 K. The formation constants of the hydrogen bonded complexes are determined by spectroscopic and ultrasonic methods and compared. These values computed by two different methods are comparable and follow similar trend. The trend in the formati...

Research paper thumbnail of Polarizable continuum model solvation analysis of halogenated pyrazole derivatives

Journal of Molecular Liquids, 2012

ABSTRACT Solvation continuum model has been used to account for solvent effects in binary mixture... more ABSTRACT Solvation continuum model has been used to account for solvent effects in binary mixtures containing two industrially important pyrazole derivatives. The solutes considered in the present investigation are 3-(4-chlorophenyl)-1H pyrazole and 3-(4-Bromophenyl)-1H pyrazole. Free energy of solvation of these two solutes in different solvents are theoretically computed and explained.

Research paper thumbnail of Spectroscopic and ultrasonic studies on the molecular interaction of certain aromatic amines with p-chloranil

Fluid Phase Equilibria, 2013

ABSTRACT Ultrasonic investigation has been carried out on five binary and four ternary liquid mix... more ABSTRACT Ultrasonic investigation has been carried out on five binary and four ternary liquid mixtures to identify the dominance of solute-solute interactions. p-Chloranil is used as acceptor and four aromatic amines are used as donors. Primary, secondary and tertiary amines were used mainly to determine the difference in the site of complex formation. The study was made in DMSO at 303 K and at atmospheric pressure. The trend in acoustical and excess thermo acoustical parameters of mixtures containing p-chloranil and amines is used to identify the existence of intermolecular interaction, probably through hydrogen bonded or charge transfer complex formation. The formation of 1:1 complexes between p-chloranil and aromatic amines was established by UV-visible spectroscopic methods at 303 K. The formation constants of the charge transfer complexes were computed by spectroscopic and ultrasonic methods which show similar trends and well establish the influence of structural aspect of the amine (donor) on the stability of charge transfer complexes.

Research paper thumbnail of Ultrasonic, spectrophotometric and theoretical studies of sigma and PI interactions of iodine with substituted benzene

The charge transfer (CT) interaction between three structurally different benzenoid compounds (do... more The charge transfer (CT) interaction between three structurally different benzenoid compounds (donors), namely, chlorobenzene (1), phenol (2), anisole (3), and iodine (I2, acceptor) were investigated by experimental methods (ultrasonic and UV-Visible analysis) and theoretical calculations. Notably, strong solute–solute interactions and the existence of a CT type of interaction between 1–3 and I2 is clearly analyzed from the trend in acoustical and excess thermo acoustical parameters with concentration at 303 K in an n-hexane medium. The formation of 1 : 1 complexes between iodine and 1–3 was established by the UV-visible spectroscopic method. The structure and stabilization energies of 1–3 and I2 were further calculated by DFT calculations. Among the s- and p-type interactions, a p-type complex (1a–3a) with an atom-centered orientation is found to be the preferred and stable geometry for all the CT complexes. The stability constant of the CT complexes was calculated by spectroscopic...

Research paper thumbnail of Polarizable continuum model solvation analysis of certain 5-substituted isoquinoline derivatives

A b s t r a c t The polarizable continuum model (PCM) analysis has been carried out using the B3... more A b s t r a c t

The polarizable continuum model (PCM) analysis has been carried out using the B3LYP method with 6-311++G(d,p) basis set for 5-bromoisoquinoline (5-BIQ), 5-aminoisoquinoline (5-AIQ), 5-nitroisoquinoline (5-NIQ), 5-methylisoquinoline (5-MIQ), 5-chloroisoquinoline (5-CIQ) and 5-methoxyisoquinoline (5-MXIQ) in
ten solventswith awide range of dielectric constants. In this paper,we report electrostatic, dispersion and repulsive interaction components of Gibb's free energy of solvation along with cavitation energies for these six systems. The induced dipole moments of these six compounds in ten solvents are calculated for the three solutes.
The interaction energies of the systems are discussed in terms of dielectric constant, index of refraction and surface tension of the solvents. The influence of substituent at 5-position of isoquinoline molecule on the solubility property is investigated.

Research paper thumbnail of Polarizable Continuum Studies on Methyl and Ethyl Substituted 2,4-Pentanedione

Journal of Solution Chemistry, 2010

The polarizable continuum solvation model (PCM) is extended to the possible tautomer forms of the... more The polarizable continuum solvation model (PCM) is extended to the possible tautomer forms of the natural alkyl substituted 2,4-pentanediones. Solvation analysis has been carried out of all of the conformers of 3-methyl and 3-ethyl substituted 2,4-pentanediones in polar and non-polar solvents having a wide range of dielectric constants. The test set consists of water, ethyl alcohol, methyl alcohol, chlorobenzene, chloroform, benzene and carbon tetrachloride. The physical properties of the systems, such as Gibbs energies, electrostatic energies and induced dipole moments are discussed. Quantum mechanical self consistent fields explain the properties of the compounds satisfactorily.

Research paper thumbnail of Polarizable continuum studies on auxin derivatives

Journal of Molecular Liquids, 2010

The Polarizable Continuum Solvation provides a way to study the solvation properties of the compo... more The Polarizable Continuum Solvation provides a way to study the solvation properties of the compounds. The Polarizable Continuum Solvation Model (PCSM) is extended to the compounds hetero auxins. The electrostatic contribution of free energy of solvation of the compounds is discussed. The effects of dispersion energy, repulsion energy, cavities and the dipole moments are examined. Thermo dynamical quantities of cavitations are calculated by different methods and compare the results. Quantum mechanical self-consistent reaction fields explain the properties of the compounds satisfactorily.

Research paper thumbnail of Ultrasonic Studies on Charge Transfer Complexes of Cyclo Alkanones with Chloroform in n Hexane Solutions

Physics and Chemistry of Liquids, 2002

The ultrasonic velocities (U), densities (ρ), and viscosities (η) were measured for solutions con... more The ultrasonic velocities (U), densities (ρ), and viscosities (η) were measured for solutions containing equimolar concentrations of eight aldehydes namely, benzaldehyde, o-chlorobenzaldehyde, anisaldehyde, p-tolualdehyde, cinnamaldehyde, crotonaldehyde, propionaldehyde, and valeraldehyde as acceptors, benzylamine and cyclohexylamine as donors in n-hexane at 303K. Acoustical parameters such as adiabatic compressibility (β), free length (L f ), viscous relaxation time (ґ), molecular interaction parameter (χ u ) have been computed. These values indicate the formation of charge transfer complexes between aldehydes and amines. Formation constant (K) values of the complexes have been evaluated using a modified Bhat equation proposed by Kannappan. The constant values of free energy of activation (∆G # ) and relaxation time indicate the formation of similar type of complexes in these systems. However, the variation in free energy of formation (∆G) values suggests that their thermodynamic stability depends on the structure of donor and acceptor.

Research paper thumbnail of Studies on free energy and its components of 2-Phenylindole and its derivatives

Journal of Molecular Liquids, 2008

... doi:10.1016/j.molliq.2007.10.012 | How to Cite or Link Using DOI Copyright © 2007 Elsevier BV... more ... doi:10.1016/j.molliq.2007.10.012 | How to Cite or Link Using DOI Copyright © 2007 Elsevier BV All rights reserved. Permissions & Reprints. Studies on free energy and its components of 2-Phenylindole and its derivatives. S. Mahalakshmi a , V. Sathyanarayanamoorthi b ...

Research paper thumbnail of Ultrasonic and spectroscopic studies on hydrogen bonded complexes of aromatic amine and aryl ketones in n-hexane at 303.15 K

Journal of Molecular Liquids, 2011

Viscometric and ultrasonic studies have been carried out in n-hexane solutions, containing equimo... more Viscometric and ultrasonic studies have been carried out in n-hexane solutions, containing equimolar concentration from 0.02 to 0.2M of aromatic ketones and N-methylaniline (NMANI), at 303.15K and at atmospheric pressure. The ketones studied in the present investigation are acetophenone (ACP), 4-chloroacetophenone (ClACP) and 4-methylacetophenone (MACP). The behaviour of measured ultrasonic velocity (u), density (ρ) and viscosity (η) and also the

Research paper thumbnail of Solvation analysis of halogenated 3-phenyl 5-amino pyrazoles

Journal of Molecular Liquids, 2011

Quantum mechanical solvation analysis accounts for electric and electro static components of solv... more Quantum mechanical solvation analysis accounts for electric and electro static components of solvation by microscopic surface tension. Solvation analysis is performed for two halo substituted phenyl 1H pyrazole-5 amines in different solvents. The free energy and its components such as electrostatic interaction, dispersion energy, and repulsion energy are computed. The systematic comparison of the electrostatic contribution of the free energy of solvation is carried out from the self-consistent reaction field. The effects of cavities and the dipole moments are examined. The investigated set consists of ten solvents with wide range of dielectric constant.

Research paper thumbnail of Solvation analysis of 1,6-di chloro hexane and 1-chloro 6-iodo hexane

Journal of Molecular Liquids, 2004

The Polarizable Continuum Solvation Model (PCSM) is extended to include compounds containing halo... more The Polarizable Continuum Solvation Model (PCSM) is extended to include compounds containing halogens. The PCSM analysis has been carried out for ClCH2(CH2)4CH2Cl and ICH2(CH2) 4CH2Cl in polar and non-polar solvents of wide range of dielectric constants. The physical properties of the systems, such as free energies, electrostatic interaction, cavitation enthalpy and dipole moment are discussed. The PCSM provides the solvation

Research paper thumbnail of Ultrasonic method of determination of stability constants of charge transfer complexes of certain carbonyl compounds and diethylamine in n-hexane

Physics and Chemistry of Liquids, 2008

The ultrasonic velocities (U), densities (ρ) and viscosities (η) were measured for solutions cont... more The ultrasonic velocities (U), densities (ρ) and viscosities (η) were measured for solutions containing equimolar concentrations of diethylamine (donor), nine aldehydes and nine ketones (acceptors) in n-hexane at 303 K. Acoustical parameters such as adiabatic compressibility (β), free length (Lf), viscous relaxation time (τ), and molecular interaction parameter (χU) have been computed. These values indicate the formation of charge transfer

Research paper thumbnail of Solubility studies of halohexanes by a quantum mechanical method

Journal of Molecular Liquids, 2006

Solvation analysis on halohexanes has been carried out by the Polarizable Continuum Model (PCM). ... more Solvation analysis on halohexanes has been carried out by the Polarizable Continuum Model (PCM). The electrostatic contribution of free energy of solvation of the compounds is discussed. The effects of dispersion energy, repulsion energy, cavities and the dipole moments are examined. The test set consists of five solvents of various range of dielectric constant. Quantum mechanical self consistent fields explain

Research paper thumbnail of Ultrasonic and Spectral Studies on Hydrogen Bonded Complexes of Aromatic Aldehydes and N-Methylaniline in n-Hexane

Journal of Applied Solution Chemistry and Modeling

Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-m... more Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-methylaniline (NMANI) and three structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde(SA) in n-hexane medium at 303.15 K and at atmospheric pressure. Acoustical parameters are computed from the measured values of ultrasonic velocity, density and dynamic viscosity. The variation of acoustical parameters in the concentration range investigated establishes complex formation through intermolecular hydrogen bonding between aldehyde and N-methylaniline. The existence of strong aldehyde-amine interaction is also confirmed through the recorded UV-Visible absorption spectra with Benesi-Hildebrand theory at 303.15 K. The formation constants of the hydrogen bonded complexes are determined by spectroscopic and ultrasonic methods and compared. These values computed by two different methods are comparable and follow similar trend. The trend in the formation constants is discussed based on structures of the component molecules and correlate with computed molecular properties.

Research paper thumbnail of Ultrasonic and Spectral Studies on Hydrogen Bonded Complexes of Aromatic Aldehydes and N-Methylaniline in n-Hexane

Journal of Applied Solution Chemistry and Modeling, 2013

Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-m... more Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-methylaniline (NMANI) and three structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde(SA) in n-hexane medium at 303.15 K and at atmospheric pressure. Acoustical parameters are computed from the measured values of ultrasonic velocity, density and dynamic viscosity. The variation of acoustical parameters in the concentration range investigated establishes complex formation through intermolecular hydrogen bonding between aldehyde and N-methylaniline. The existence of strong aldehyde-amine interaction is also confirmed through the recorded UV-Visible absorption spectra with Benesi-Hildebrand theory at 303.15 K. The formation constants of the hydrogen bonded complexes are determined by spectroscopic and ultrasonic methods and compared. These values computed by two different methods are comparable and follow similar trend. The trend in the formation constants is discussed based on structures of the component molecules and correlate with computed molecular properties.

Research paper thumbnail of Spectroscopic Characterization and Electronic Structure Analysis of Linagliptin by DFT Method

NIScPR-CSIR, India, Sep 1, 2021

Введение. Рынки труда регионов Арктической зоны Российской Федерации испытывают потребность в кад... more Введение. Рынки труда регионов Арктической зоны Российской Федерации испытывают потребность в кадрах, которым предстоит работать в экстремальных условиях крайнего Севера. Это объективное обстоятельство накладывает особенные, зачастую, повышенные требования к квалификации и уровню подготовки соискателей работы, в том числе, и к качеству их образования. Актуальность данного исследования обуславливается набирающей популярность формой онлайн-обучения, которой свойственны как достоинства, связанные с доступностью такого образования и его безопасностью в эпоху пандемии, так и недостатки, связанные с качеством получаемого образования. Цель исследования-анализ востребованности специалистов, получивших профессиональное образование в дистанционной онлайн-форме, на рынке труда регионов Арктической зоны Российской Федерации. Материалы и методы. Информационной базой исследования послужили результаты опроса более 2200 работодателей из территорий всех 9 субъектов Российской Федерации, входящих в Арктическую зону. Опросы проводились методами онлайн анкетирования. При обработке результатов опроса использовались методы описательной статистики, системного анализа и сравнительный анализ данных. Результаты исследования. Применимость практики получения профессионального образования в онлайн-форме для условий Арктической зоны одобряют 58% опрошенных работодателей, а 42% относятся к этому отрицательно. Только каждый третий опрошенный работодатель считает существующую в АЗ РФ систему онлайн-образования в целом соответствующей их требованиям к такому типу подготовки. При этом чуть более 40% работодателей всех арктических регионов выразили готовность принять в штат специалистов с дипломом об онлайн-образовании. Результаты опроса, представленные в разрезе арктических регионов и видов экономической деятельности, показали неоднородное отношение работодателей к исследуемым вопросам. Обсуждение и заключение. Полученные результаты подтвердили значимость для работодателей АЗ РФ вопросов подготовки кадров с применением онлайн-обучения, которое обладает как рядом несомненных преимуществ для арктических территорий, так и ограничений. Важным направлением развития исследования является оценка возможностей существующей системы дистанционного онлайн-образования с позиции самих субъектов образования-вузов и колледжей, расположенных в Арктической зоне России.

Research paper thumbnail of Ultrasonic, spectrophotometric and theoretical studies of sigma and PI interactions of iodine with substituted benzene

RSC Advances, 2015

The acoustical method shows the ability to study the structure, energetics and spectroscopic aspe... more The acoustical method shows the ability to study the structure, energetics and spectroscopic aspects of charge transfer complexes of three different benzenoid compounds with iodine and is supported by the UV-Visible and DFT methods.

Research paper thumbnail of Studies on free energies of solution and its components of thiazole amine derivatives

Journal of Molecular Liquids, 2012

Abstract The polarizable continuum model (PCM) is employed to investigate theoretically the solva... more Abstract The polarizable continuum model (PCM) is employed to investigate theoretically the solvation of two heterocyclic compounds containing halogens. The PCM analysis has been carried out for 4-(4-chlorophenyl)-1,3-thiazol-2-amine and 4-(4-bromophenyl)-1,3-thiazol-2-amine in ten solvents with wide range of dielectric constants. In this paper, we report the results obtained in the computation of electrostatic interaction, repulsive component of Gibb's free energy of solvation, cavitation enthalpy and entropy of solvation for the two thiazole amines in various solvents. The dipole moments of the two amine molecules are calculated theoretically by AM1, PM3, MNDO and ab initio methods. The induced dipole moments of these two thiazoles are also calculated in these solvents. The thermodynamic properties of the systems, such as free energies, electrostatic interaction, cavitation enthalpy and dipole moment are discussed in terms of the physical properties such as dielectric constant, index of refraction, surface tension and molecular size of the solvents.

Research paper thumbnail of Studies on nano suspensions of silver sol and redispersed nanocrystallite silver in aqueous and alcoholic media

Journal of Molecular Liquids, 2011

Nanocrystallite silver and silver sol were prepared and characterized by UV-visible spectra, XRD,... more Nanocrystallite silver and silver sol were prepared and characterized by UV-visible spectra, XRD, TEM and HRTEM. The crystallite silver is re-dispersed in two different media, namely, water and alcohol and sonicated before ultrasonic investigation. The silver sol was used as such. Three different models for the propagation of ultrasound through two phase media are compared in these three different types of nano suspensions. Effect of particle size and medium on ultrasonic velocity (U), compressibility (κ) impedance (Z) and viscous relaxation time (τ) is studied. The particle concentration range was 0.2-1 v/v. Density and viscosity of the dispersion and sol are measured at different particle volume fractions. Effective density and ultrasonic velocity are computed by Urick, Kuster and Toksöz and Urick and Ament models and compared with experimental velocities. Values of effective density obtained by using Urick and Urick and Ament equations closely agree with experimental results of density while Urick's equation prediction of velocity is in close agreement with the experimental velocities. This comes as a surprise in view of the large density difference between the medium and suspended particle and suggests the possibility of the balancing effect of the inertial and viscous forces operating in the suspension.

Research paper thumbnail of Ultrasonic and Spectral Studies on Hydrogen Bonded Complexes of Aromatic Aldehydes and N-Methylaniline in n-Hexane

Journal of Applied Solution Chemistry and Modeling, 2013

Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-m... more Ultrasonic and UV-spectral studies have been carried out for three ternary systems containing N-methylaniline (NMANI) and three structurally different aromatic aldehydes, benzaldehyde (BA), cinnamaldehyde (CA) and salicylaldehyde(SA) in n-hexane medium at 303.15 K and at atmospheric pressure. Acoustical parameters are computed from the measured values of ultrasonic velocity, density and dynamic viscosity. The variation of acoustical parameters in the concentration range investigated establishes complex formation through intermolecular hydrogen bonding between aldehyde and N-methylaniline. The existence of strong aldehyde-amine interaction is also confirmed through the recorded UV-Visible absorption spectra with Benesi-Hildebrand theory at 303.15 K. The formation constants of the hydrogen bonded complexes are determined by spectroscopic and ultrasonic methods and compared. These values computed by two different methods are comparable and follow similar trend. The trend in the formati...

Research paper thumbnail of Polarizable continuum model solvation analysis of halogenated pyrazole derivatives

Journal of Molecular Liquids, 2012

ABSTRACT Solvation continuum model has been used to account for solvent effects in binary mixture... more ABSTRACT Solvation continuum model has been used to account for solvent effects in binary mixtures containing two industrially important pyrazole derivatives. The solutes considered in the present investigation are 3-(4-chlorophenyl)-1H pyrazole and 3-(4-Bromophenyl)-1H pyrazole. Free energy of solvation of these two solutes in different solvents are theoretically computed and explained.

Research paper thumbnail of Spectroscopic and ultrasonic studies on the molecular interaction of certain aromatic amines with p-chloranil

Fluid Phase Equilibria, 2013

ABSTRACT Ultrasonic investigation has been carried out on five binary and four ternary liquid mix... more ABSTRACT Ultrasonic investigation has been carried out on five binary and four ternary liquid mixtures to identify the dominance of solute-solute interactions. p-Chloranil is used as acceptor and four aromatic amines are used as donors. Primary, secondary and tertiary amines were used mainly to determine the difference in the site of complex formation. The study was made in DMSO at 303 K and at atmospheric pressure. The trend in acoustical and excess thermo acoustical parameters of mixtures containing p-chloranil and amines is used to identify the existence of intermolecular interaction, probably through hydrogen bonded or charge transfer complex formation. The formation of 1:1 complexes between p-chloranil and aromatic amines was established by UV-visible spectroscopic methods at 303 K. The formation constants of the charge transfer complexes were computed by spectroscopic and ultrasonic methods which show similar trends and well establish the influence of structural aspect of the amine (donor) on the stability of charge transfer complexes.

Research paper thumbnail of Ultrasonic, spectrophotometric and theoretical studies of sigma and PI interactions of iodine with substituted benzene

The charge transfer (CT) interaction between three structurally different benzenoid compounds (do... more The charge transfer (CT) interaction between three structurally different benzenoid compounds (donors), namely, chlorobenzene (1), phenol (2), anisole (3), and iodine (I2, acceptor) were investigated by experimental methods (ultrasonic and UV-Visible analysis) and theoretical calculations. Notably, strong solute–solute interactions and the existence of a CT type of interaction between 1–3 and I2 is clearly analyzed from the trend in acoustical and excess thermo acoustical parameters with concentration at 303 K in an n-hexane medium. The formation of 1 : 1 complexes between iodine and 1–3 was established by the UV-visible spectroscopic method. The structure and stabilization energies of 1–3 and I2 were further calculated by DFT calculations. Among the s- and p-type interactions, a p-type complex (1a–3a) with an atom-centered orientation is found to be the preferred and stable geometry for all the CT complexes. The stability constant of the CT complexes was calculated by spectroscopic...

Research paper thumbnail of Polarizable continuum model solvation analysis of certain 5-substituted isoquinoline derivatives

A b s t r a c t The polarizable continuum model (PCM) analysis has been carried out using the B3... more A b s t r a c t

The polarizable continuum model (PCM) analysis has been carried out using the B3LYP method with 6-311++G(d,p) basis set for 5-bromoisoquinoline (5-BIQ), 5-aminoisoquinoline (5-AIQ), 5-nitroisoquinoline (5-NIQ), 5-methylisoquinoline (5-MIQ), 5-chloroisoquinoline (5-CIQ) and 5-methoxyisoquinoline (5-MXIQ) in
ten solventswith awide range of dielectric constants. In this paper,we report electrostatic, dispersion and repulsive interaction components of Gibb's free energy of solvation along with cavitation energies for these six systems. The induced dipole moments of these six compounds in ten solvents are calculated for the three solutes.
The interaction energies of the systems are discussed in terms of dielectric constant, index of refraction and surface tension of the solvents. The influence of substituent at 5-position of isoquinoline molecule on the solubility property is investigated.

Research paper thumbnail of Polarizable Continuum Studies on Methyl and Ethyl Substituted 2,4-Pentanedione

Journal of Solution Chemistry, 2010

The polarizable continuum solvation model (PCM) is extended to the possible tautomer forms of the... more The polarizable continuum solvation model (PCM) is extended to the possible tautomer forms of the natural alkyl substituted 2,4-pentanediones. Solvation analysis has been carried out of all of the conformers of 3-methyl and 3-ethyl substituted 2,4-pentanediones in polar and non-polar solvents having a wide range of dielectric constants. The test set consists of water, ethyl alcohol, methyl alcohol, chlorobenzene, chloroform, benzene and carbon tetrachloride. The physical properties of the systems, such as Gibbs energies, electrostatic energies and induced dipole moments are discussed. Quantum mechanical self consistent fields explain the properties of the compounds satisfactorily.

Research paper thumbnail of Polarizable continuum studies on auxin derivatives

Journal of Molecular Liquids, 2010

The Polarizable Continuum Solvation provides a way to study the solvation properties of the compo... more The Polarizable Continuum Solvation provides a way to study the solvation properties of the compounds. The Polarizable Continuum Solvation Model (PCSM) is extended to the compounds hetero auxins. The electrostatic contribution of free energy of solvation of the compounds is discussed. The effects of dispersion energy, repulsion energy, cavities and the dipole moments are examined. Thermo dynamical quantities of cavitations are calculated by different methods and compare the results. Quantum mechanical self-consistent reaction fields explain the properties of the compounds satisfactorily.

Research paper thumbnail of Ultrasonic Studies on Charge Transfer Complexes of Cyclo Alkanones with Chloroform in n Hexane Solutions

Physics and Chemistry of Liquids, 2002

The ultrasonic velocities (U), densities (ρ), and viscosities (η) were measured for solutions con... more The ultrasonic velocities (U), densities (ρ), and viscosities (η) were measured for solutions containing equimolar concentrations of eight aldehydes namely, benzaldehyde, o-chlorobenzaldehyde, anisaldehyde, p-tolualdehyde, cinnamaldehyde, crotonaldehyde, propionaldehyde, and valeraldehyde as acceptors, benzylamine and cyclohexylamine as donors in n-hexane at 303K. Acoustical parameters such as adiabatic compressibility (β), free length (L f ), viscous relaxation time (ґ), molecular interaction parameter (χ u ) have been computed. These values indicate the formation of charge transfer complexes between aldehydes and amines. Formation constant (K) values of the complexes have been evaluated using a modified Bhat equation proposed by Kannappan. The constant values of free energy of activation (∆G # ) and relaxation time indicate the formation of similar type of complexes in these systems. However, the variation in free energy of formation (∆G) values suggests that their thermodynamic stability depends on the structure of donor and acceptor.

Research paper thumbnail of Studies on free energy and its components of 2-Phenylindole and its derivatives

Journal of Molecular Liquids, 2008

... doi:10.1016/j.molliq.2007.10.012 | How to Cite or Link Using DOI Copyright © 2007 Elsevier BV... more ... doi:10.1016/j.molliq.2007.10.012 | How to Cite or Link Using DOI Copyright © 2007 Elsevier BV All rights reserved. Permissions & Reprints. Studies on free energy and its components of 2-Phenylindole and its derivatives. S. Mahalakshmi a , V. Sathyanarayanamoorthi b ...

Research paper thumbnail of Ultrasonic and spectroscopic studies on hydrogen bonded complexes of aromatic amine and aryl ketones in n-hexane at 303.15 K

Journal of Molecular Liquids, 2011

Viscometric and ultrasonic studies have been carried out in n-hexane solutions, containing equimo... more Viscometric and ultrasonic studies have been carried out in n-hexane solutions, containing equimolar concentration from 0.02 to 0.2M of aromatic ketones and N-methylaniline (NMANI), at 303.15K and at atmospheric pressure. The ketones studied in the present investigation are acetophenone (ACP), 4-chloroacetophenone (ClACP) and 4-methylacetophenone (MACP). The behaviour of measured ultrasonic velocity (u), density (ρ) and viscosity (η) and also the

Research paper thumbnail of Solvation analysis of halogenated 3-phenyl 5-amino pyrazoles

Journal of Molecular Liquids, 2011

Quantum mechanical solvation analysis accounts for electric and electro static components of solv... more Quantum mechanical solvation analysis accounts for electric and electro static components of solvation by microscopic surface tension. Solvation analysis is performed for two halo substituted phenyl 1H pyrazole-5 amines in different solvents. The free energy and its components such as electrostatic interaction, dispersion energy, and repulsion energy are computed. The systematic comparison of the electrostatic contribution of the free energy of solvation is carried out from the self-consistent reaction field. The effects of cavities and the dipole moments are examined. The investigated set consists of ten solvents with wide range of dielectric constant.

Research paper thumbnail of Solvation analysis of 1,6-di chloro hexane and 1-chloro 6-iodo hexane

Journal of Molecular Liquids, 2004

The Polarizable Continuum Solvation Model (PCSM) is extended to include compounds containing halo... more The Polarizable Continuum Solvation Model (PCSM) is extended to include compounds containing halogens. The PCSM analysis has been carried out for ClCH2(CH2)4CH2Cl and ICH2(CH2) 4CH2Cl in polar and non-polar solvents of wide range of dielectric constants. The physical properties of the systems, such as free energies, electrostatic interaction, cavitation enthalpy and dipole moment are discussed. The PCSM provides the solvation

Research paper thumbnail of Ultrasonic method of determination of stability constants of charge transfer complexes of certain carbonyl compounds and diethylamine in n-hexane

Physics and Chemistry of Liquids, 2008

The ultrasonic velocities (U), densities (ρ) and viscosities (η) were measured for solutions cont... more The ultrasonic velocities (U), densities (ρ) and viscosities (η) were measured for solutions containing equimolar concentrations of diethylamine (donor), nine aldehydes and nine ketones (acceptors) in n-hexane at 303 K. Acoustical parameters such as adiabatic compressibility (β), free length (Lf), viscous relaxation time (τ), and molecular interaction parameter (χU) have been computed. These values indicate the formation of charge transfer

Research paper thumbnail of Solubility studies of halohexanes by a quantum mechanical method

Journal of Molecular Liquids, 2006

Solvation analysis on halohexanes has been carried out by the Polarizable Continuum Model (PCM). ... more Solvation analysis on halohexanes has been carried out by the Polarizable Continuum Model (PCM). The electrostatic contribution of free energy of solvation of the compounds is discussed. The effects of dispersion energy, repulsion energy, cavities and the dipole moments are examined. The test set consists of five solvents of various range of dielectric constant. Quantum mechanical self consistent fields explain