Ashma Aggarwal | St. Xavier's College, Mumbai (original) (raw)

Papers by Ashma Aggarwal

Research paper thumbnail of Thermodynamic and topological investigation of the interaction between methimazole and Mz+ (Na+, Li+, Ca2+ and Mg2+)

Computational and Theoretical Chemistry, 2012

Structures and thermodynamic properties of complexes formed from interaction between the methimaz... more Structures and thermodynamic properties of complexes formed from interaction between the methimazole (MMI) as an anti-thyroid drug and M z+ (Ca 2+ , Mg 2+ , Na + and Li +) were investigated at various levels of theory. We have found two types planar and non-planar MMI-M z+ complexes on the potential energy surface. From the Gibbs free energy difference between the planar and non-planar forms of MMI-M z+ complexes, it is found that the non-planar forms are the predominant ones. In addition, stability of MMI-M z+ complexes increases in the following order: Na + < Li + < Ca 2+ < Mg 2+. NBO analysis confirms that the charge transfer takes place from MMI to metal cations. The AIM theory was applied to analyze the topological properties of the bond critical points (electron densities and their Laplacians) involved in the interaction between MMI and the metal cations. It was revealed that the SAM z+ interactions in non-planar complexes of alkali and alkaline metal ions are electrostatic and partially covalent in nature, respectively. In addition, covalent nature of CAS bond decreases upon complex formation.

Research paper thumbnail of Molar excess volumes and molar excess enthalpies of binary mixtures containing nitrobenzene

46-52Molar excess voiumes, VE, and molar excess enthalpies, HE, for nitrobenzene (i) + benzene, +... more 46-52Molar excess voiumes, VE, and molar excess enthalpies, HE, for nitrobenzene (i) + benzene, +toluene or + O: or +p-xyleneU) binary mixtures have been measured as a function of composition at 298.15 and 308.15 K. The observed data have been analysed in terms of graph-theoretical approach. The analysis of VE data by graph-theoretical approach reveals that these (i+j) mixtures are characterised by interactions between the delocalised π-electron cloud of nitro group of nitrobenzene and π-electron cloud of aromatic ring of benzene, toluene, or O: or p-xylene leading to the formation of 1:1 molecular complex. The 1R studies lend additional support to the nature and extent of interactions for proposed structure in the mixture. The results have also been analysed in terms of (i) Flory's and (ii) Sanchez and Lacombe's theory

Research paper thumbnail of Thermodynamics of ternary mixtures: Excess isentropic compressibilities

Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical, 2003

Ultrasonic velocity data for nitrobenzene(i) + benzene(j) + toluene or + o-xylene, or + p-xylene ... more Ultrasonic velocity data for nitrobenzene(i) + benzene(j) + toluene or + o-xylene, or + p-xylene (k) ternary mixtures have been determined as a function of composition at 298.15K. The observed data have been utilized to evaluate excess isentroic compressibilities. K E S . K E S values have also been computed using Flory theory. It has been observed that K E S values evaluated from Flory theory make qualitative agreement with the values evaluated from experimental data.

Research paper thumbnail of Molar Excess Enthalpies of Ternary Mixtures Containing Nitrobenzene

Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical, 1998

Molar excess enthalpies, Jf.,jk' of nitrobenzene (i) + benzene (j) + cyclohexane or +n-hexane or ... more Molar excess enthalpies, Jf.,jk' of nitrobenzene (i) + benzene (j) + cyclohexane or +n-hexane or + n-heptane (k) ternary mixtures have been measured as a function of composition at 308.15 K. The observed. data have been analysed in terms of i) Flory's theory and ii) Sanchez and Lacombe theory of fluid mixtures. J!ijk values predicted by Flory theory and Sanchez and Lacombe theory make only qualitative agreement. Recently thermodynamics1-s of ternary (i+j+k) mixtures of non-electrolytes has received the attention of many workers, as all thermodynamic properties of ternary mixtures can be determined when the corresponding properties of (i+j), (j+k) and (i+k) binary mixtures are known. In our earlier communication6, molar excess enthalpies, Il;j, for nitrobenzene (i) + benzene or + toluene or + o-,+pxylene (j) binary mixtures have been ana lysed in terms of Flory's theory and graph-theoretical approach. This prompted us to (i) measure the molar excess enthalpies, Il;jk, of the nitrobenzene (i) + benzene (j) + cyclohexane or +n-hexane or +n-heptane (k) ternary mixtures and (ii) see how the molar excess enthalpies, Il;jk data of the these ternary mixtures are explained 6y Flory's theory and Sanchez and Lacombe approach of nonelectrolyte solution.

Research paper thumbnail of Thermodynamical Investigations of Some Non-Electrolytic Ternary Mixtures

Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical, 1998

Molar excess volume, vE.k and molar excess enthalpies ff:k of various nitrobenzene (i) + benzene ... more Molar excess volume, vE.k and molar excess enthalpies ff:k of various nitrobenzene (i) + benzene U) + toluene (k) ij ij nitrobenzene (i) + benzene U) + 0-xylene (k) and nitrobenzene (i) + benzene U) + p-xylene (k) te nary mixtures have been measured as a function of composition at 298.15 K. The observed data have been analysed n terms of i) Graph theory, ii) Sanchez and Lacombe and iii) Flory's theories. The calculated xE.k values (X = Vor H) by Graph and Flory's v theories compare well with their corresponding experimental values.

Research paper thumbnail of Excess molar volumes and excess molar enthalpies for binary mixtures of 1,2-dichloropropane with methyl ethanoate, methyl propanoate, and methyl butanoate at T=298.15K

Fluid Phase Equilibria, 2011

ABSTRACT The excess molar volumes VmE and excess molar enthalpies HmE have been measured for the ... more ABSTRACT The excess molar volumes VmE and excess molar enthalpies HmE have been measured for the binary mixtures of {1,2-dichloropropane+methyl ethanoate, or +methyl propanoate, or +methyl butanoate} using a densimeter and an isothermal microcalorimeter, respectively, at T=298.15K and P=1atm. The HmE values of all binary mixtures are negative while VmE values are positive over the whole composition range. Both VmE and HmE values decrease with an increase of molecular weight of methyl esters. The maximum negative values of HmE for these binary systems were observed at x1=0.45–0.51. But, the maximum positive values of VmE lie at 0.49–0.65 mole fraction of 1,2-dichloropropane. The experimental results are discussed in terms of intermolecular interactions, particularly the self-association by dipole–dipole attraction between like and unlike molecules and formation of empty space around the molecules in the mixtures. The experimental data were correlated by three local-composition models (Wilson, NRTL, and UNIQUAC). Out of three models, NRTL equation provides the most appropriate correlating results except the binary system containing methyl butanoate.

Research paper thumbnail of Thermodynamic and topological investigation of the interaction between methimazole and Mz+ (Na+, Li+, Ca2+ and Mg2+)

Computational and Theoretical Chemistry, 2012

Structures and thermodynamic properties of complexes formed from interaction between the methimaz... more Structures and thermodynamic properties of complexes formed from interaction between the methimazole (MMI) as an anti-thyroid drug and M z+ (Ca 2+ , Mg 2+ , Na + and Li +) were investigated at various levels of theory. We have found two types planar and non-planar MMI-M z+ complexes on the potential energy surface. From the Gibbs free energy difference between the planar and non-planar forms of MMI-M z+ complexes, it is found that the non-planar forms are the predominant ones. In addition, stability of MMI-M z+ complexes increases in the following order: Na + < Li + < Ca 2+ < Mg 2+. NBO analysis confirms that the charge transfer takes place from MMI to metal cations. The AIM theory was applied to analyze the topological properties of the bond critical points (electron densities and their Laplacians) involved in the interaction between MMI and the metal cations. It was revealed that the SAM z+ interactions in non-planar complexes of alkali and alkaline metal ions are electrostatic and partially covalent in nature, respectively. In addition, covalent nature of CAS bond decreases upon complex formation.

Research paper thumbnail of Molar excess volumes and molar excess enthalpies of binary mixtures containing nitrobenzene

46-52Molar excess voiumes, VE, and molar excess enthalpies, HE, for nitrobenzene (i) + benzene, +... more 46-52Molar excess voiumes, VE, and molar excess enthalpies, HE, for nitrobenzene (i) + benzene, +toluene or + O: or +p-xyleneU) binary mixtures have been measured as a function of composition at 298.15 and 308.15 K. The observed data have been analysed in terms of graph-theoretical approach. The analysis of VE data by graph-theoretical approach reveals that these (i+j) mixtures are characterised by interactions between the delocalised π-electron cloud of nitro group of nitrobenzene and π-electron cloud of aromatic ring of benzene, toluene, or O: or p-xylene leading to the formation of 1:1 molecular complex. The 1R studies lend additional support to the nature and extent of interactions for proposed structure in the mixture. The results have also been analysed in terms of (i) Flory's and (ii) Sanchez and Lacombe's theory

Research paper thumbnail of Thermodynamics of ternary mixtures: Excess isentropic compressibilities

Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical, 2003

Ultrasonic velocity data for nitrobenzene(i) + benzene(j) + toluene or + o-xylene, or + p-xylene ... more Ultrasonic velocity data for nitrobenzene(i) + benzene(j) + toluene or + o-xylene, or + p-xylene (k) ternary mixtures have been determined as a function of composition at 298.15K. The observed data have been utilized to evaluate excess isentroic compressibilities. K E S . K E S values have also been computed using Flory theory. It has been observed that K E S values evaluated from Flory theory make qualitative agreement with the values evaluated from experimental data.

Research paper thumbnail of Molar Excess Enthalpies of Ternary Mixtures Containing Nitrobenzene

Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical, 1998

Molar excess enthalpies, Jf.,jk' of nitrobenzene (i) + benzene (j) + cyclohexane or +n-hexane or ... more Molar excess enthalpies, Jf.,jk' of nitrobenzene (i) + benzene (j) + cyclohexane or +n-hexane or + n-heptane (k) ternary mixtures have been measured as a function of composition at 308.15 K. The observed. data have been analysed in terms of i) Flory's theory and ii) Sanchez and Lacombe theory of fluid mixtures. J!ijk values predicted by Flory theory and Sanchez and Lacombe theory make only qualitative agreement. Recently thermodynamics1-s of ternary (i+j+k) mixtures of non-electrolytes has received the attention of many workers, as all thermodynamic properties of ternary mixtures can be determined when the corresponding properties of (i+j), (j+k) and (i+k) binary mixtures are known. In our earlier communication6, molar excess enthalpies, Il;j, for nitrobenzene (i) + benzene or + toluene or + o-,+pxylene (j) binary mixtures have been ana lysed in terms of Flory's theory and graph-theoretical approach. This prompted us to (i) measure the molar excess enthalpies, Il;jk, of the nitrobenzene (i) + benzene (j) + cyclohexane or +n-hexane or +n-heptane (k) ternary mixtures and (ii) see how the molar excess enthalpies, Il;jk data of the these ternary mixtures are explained 6y Flory's theory and Sanchez and Lacombe approach of nonelectrolyte solution.

Research paper thumbnail of Thermodynamical Investigations of Some Non-Electrolytic Ternary Mixtures

Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical, 1998

Molar excess volume, vE.k and molar excess enthalpies ff:k of various nitrobenzene (i) + benzene ... more Molar excess volume, vE.k and molar excess enthalpies ff:k of various nitrobenzene (i) + benzene U) + toluene (k) ij ij nitrobenzene (i) + benzene U) + 0-xylene (k) and nitrobenzene (i) + benzene U) + p-xylene (k) te nary mixtures have been measured as a function of composition at 298.15 K. The observed data have been analysed n terms of i) Graph theory, ii) Sanchez and Lacombe and iii) Flory's theories. The calculated xE.k values (X = Vor H) by Graph and Flory's v theories compare well with their corresponding experimental values.

Research paper thumbnail of Excess molar volumes and excess molar enthalpies for binary mixtures of 1,2-dichloropropane with methyl ethanoate, methyl propanoate, and methyl butanoate at T=298.15K

Fluid Phase Equilibria, 2011

ABSTRACT The excess molar volumes VmE and excess molar enthalpies HmE have been measured for the ... more ABSTRACT The excess molar volumes VmE and excess molar enthalpies HmE have been measured for the binary mixtures of {1,2-dichloropropane+methyl ethanoate, or +methyl propanoate, or +methyl butanoate} using a densimeter and an isothermal microcalorimeter, respectively, at T=298.15K and P=1atm. The HmE values of all binary mixtures are negative while VmE values are positive over the whole composition range. Both VmE and HmE values decrease with an increase of molecular weight of methyl esters. The maximum negative values of HmE for these binary systems were observed at x1=0.45–0.51. But, the maximum positive values of VmE lie at 0.49–0.65 mole fraction of 1,2-dichloropropane. The experimental results are discussed in terms of intermolecular interactions, particularly the self-association by dipole–dipole attraction between like and unlike molecules and formation of empty space around the molecules in the mixtures. The experimental data were correlated by three local-composition models (Wilson, NRTL, and UNIQUAC). Out of three models, NRTL equation provides the most appropriate correlating results except the binary system containing methyl butanoate.