Shipra Baluja

Evaluation of biological activities of some Schiff bases and metal complexes

Several Schiff bases were synthesised from sulphonamide and resacetophenone. The characterisation was done by CHN analysis, IR and NMR spectral data. These Schiff bases were evaluated for their antimicrobial activity against both Gram-positive and Gram-negative bacteria as well as fungi. The antibacterial activity was studied against B. megaterium, E. coli, B. subtilis, P. fluorescens and antifungal activity against A. awamori. In addition, copper, nickel, cobalt, and iron complexes of two Schiff bases were also synthesised. Their structural characterisation was performed using CHN analysis and IR spectral data and their antibacterial and antifungal activities were also evaluated. The comparison of antimicrobial activities of the ligands and complexes shows that the presence of metal causes more inhibition i.e., more activity. Out of the four metals studied, cobalt and iron were found to have more antimicrobial activity.

Studies on acoustical properties of poly(4,4'-cyclopentylidene diphenylene toluene-2,4-disulfonate) in different solvents at 30°C

Abstract Various acoustical parameters of poly(4,4′-cyclopentylidene diphenylene toluene-2,4-disulfonate) (PSBPT) in chloroform, 1,2-dichloroethane, 1,4-dioxane and tetrahydrofuran were evaluated at 30°C using an interferometer operating at a frequency of 3 MHz. Some of these parameters, except the internal pressure, relaxation time, classical absorption coefficient and solvation number, were correlated with concentration. Excellent linear correlations between the parameters U , Z , K s , R , b , L f and r and concentration are observed. The increase of U , Z , R , b , P and decrease of K s , r and L f with increasing solute concentration C indicated polymer-solvent interaction. The positive values of the solvation number further supported the structure forming tendency of PSBPT. The relative viscosity against C plots indicated structural changes take place after 1% concentration except for the tetrahydrofuran system where it is observed at about 2% concentration; due to polymer-polymer entanglement.

Spectroscopic and calorimetric studies of proton tunneling and deuteration-induced phase transition in crystalline iodo-hydroxyphenalenone and iodo-deuteroxyphenalenone

Abstract Far-infrared spectra and molar heat capacities of 5-iodo-9-hydroxyphenalenone (IHP) and its deuterated analog (IDP) were measured at temperatures between 5 K and ambient temperature. A strong absorption at 68 cm −1 in IHP, for which the counterpart is missing in IDP, was assigned to the proton tunneling. A heat capacity anomaly due to a phase transition occurred at 36.0 K in IDP with Δ trs H=167 J mol −1 and Δ trs S=5.45 J K −1 mol −1 . No phase transition occurred in IHP, proving mutual exclusion of the tunneling and order–disorder transition. The results provide firm experimental evidence for discrete tunnel states in hydrogen-bonded crystals, the key concept in the theory of deuterium isotope effects in ferroelectricity.

Acoustical Studies of Schiff Bases in 1,4-dioxane and Dimethylformamide at 308.15 K

The density, viscosity, and ultrasonic velocity of solutions of two schiff bases in 1,4-dioxane and dimethylformamide (DMF) were measured at 318.15 K. Various acoustical properties, such as the specific impedance (Z), isentropic compressibility (κs), Rao’s molar sound function (Rm), van der Waals constant (b), molar compressibility (W), intermolecular free length (Lf), relaxation strength (r), relative association (RA), and free volume (Vf), were calculated. The results were interpreted in terms of molecular interactions occurring in the solutions.

Studies on Thermodynamic Properties of Some Imidazolinone Derivatives in DMF at 308.15 K

Abstract Density, ultrasonic velocity and viscosity of imidazolinone derivatives are studied in dimethyl formamide (DMF) at 308.15 K. From the experimental data, various acoustical parameters, such as specific impedance Z , isentropic compressibility κ s , Raos molar sound function R m , van der Waals constant b , relaxation strength r , intermolecular free length L f , internal pressure π, solvation number S n , relative association R A , etc . are evaluated, which helps in understanding the molecular interactions occurring in these solutions.

Acoustical Studies of Schiff Bases in 1, 4-dioxane and Dimethylformamide at 308.15 K

From experimental data of density, viscosity and ultrasonic velocity, the various acoustical properties, such as specific impedance (Z), isentropic compressibility (κs), Raos molar sound function (Rm), the van der Waals constant (b), molar compressibility (W), intermolecular free length (Lf), relaxation strength (r), internal pressure (π), free volume (Vf), solvation number (Sn) etc., were calculated for three Schiff bases in 1,4-dioxane and dimethylformamide (DMF) at 318.15 K. The results are interpreted in terms of molecular interactions occurring in the solutions.

Thermodynamic and acoustical studies of binary mixtures of diethyl malonate at 308.15K

The density, viscosity, refractive index and speed of sound of binary mixtures of diethyl malonate with 1,4-dioxane, dimethyl formamide, tetrahydrofuran and hexane were measured at 308.15 K. Various acoustical and thermodynamic parameters were evaluated using these experimental data and the results have been explained on the basis of molecular interactions and geometric effects of the components in the mixture.

Acoustical studies of some derivatives of 1,5-benzodiazepines formamide and tetrahydrofuran solutions at 298.15 K

Some derivatives of 1,5-benzodiazepines have been synthesized and characterized by TLC, IR, NMR, and Mass Spectral data. The ultrasonic velocity, density and viscosity of these synthesized compounds have been measured in dimethyl formamide and tetrahydrofuran at 298.15 K. From these experimental data, various acoustical parameters such as isentropic compressibility, intermolecular free path length, molar compressibility, Rao’s molar sound function, relaxation strength, internal pressure, free volume etc., have been calculated which helps in understanding the molecular interactions occurring in these solutions.

Ferroelectric phase transitions in Pb2xSn2(1-x)P2Se6 system

Heat capacities of the Pb2xSn2(1-x)P2Se6 crystals (x=0, 0.098, 0.251, 0.402 and 1.0) were measured using an adiabatic calorimeter at temperatures between 10 and 350 K. In the crystal of x=0, two heat capacity anomalies corresponding to the ferroelectric commensurate - intermediate incommensurate(C-IC) phase transition temperature Ti, and the incommensurate - paraelectric (IC-N) phase transition temperature Tc, were observed at 193.24±0.10 and 220.07±0.15 K, respectively. The phase transition temperatures decreased with an increase in Pb2+ concentration. The anomaly at Ti disappeared at x=0.251 in the mixed systems of the Pb2xSn2(1-x)P2Se6. In the crystal of Pb2P2Se6 (x=1.0), no phase transition was observed. The normal heat capacities for the mixed crystals were determined by least squares fitting of the Debye and Einstein functions to the experimental data. The anomalous heat capacities gave the phase transition entropies of 8.5 and 1.5 J mol-1 K-1 for x=0. The large transition entropies are consistent with an order-disorder mechanism in the ferroelectric-paraelectric phase transitions in x=0.

Measurement and Correlation for Solubility of Some Pyrimidine Derivatives in Different Solvents

Some new pyrimidine derivatives have been synthesized and their characterization was done by IR, NMR, and mass spectral data. The solubility of these synthesized compounds has been studied in methanol, N,N dimethylformamide (DMF), and carbon tetrachloride (CCl4) by gravimetrical method from 298.15 to 328.15 K under atmospheric pressure and the solubility data were correlated against temperature. The solubility is found to increase with temperature and order of solubility is DMF > methanol > CCl4. The experimental solubility data is correlated with the modified Apelblat equation. Some thermodynamic parameters such as dissolution enthalpy, Gibbs energy of dissolution, and entropy of mixing have also been calculated.