Apparent Entropy Research Articles

Transition Metal Complexes of a Novel Polymeric Ligand: Thermal Degradation Kinetics and In Vitro Antibacterial Applications

A novel polymeric ligand poly(2-amino-3-((2-methyl-4-nitrophenylamino)methyl)benzoic acid) was synthesized using solution condensation technique in acid medium. Metal complexes were prepared using the polymer as ligand. The synthesized ligand and its metal complexes were characterized by FTIR, electronic, ESR and NMR (1H and 13C) spectroscopy. The number, weight, size average molecular weights of the ligand were calculated by gel permeation chromatography. The surface morphology and the nature of the synthesized compounds were examined by SEM and XRD. The thermal behavior of the compounds was determined by thermogravimetric analysis. Thermal degradation kinetics such as activation energy (Ea), order of reaction (n) and thermodynamics viz. entropy change (ΔS), apparent entropy (S*), frequency factor (Z) and free energy change (ΔF) were also evaluated for the ligand and its metal complexes by Freeman–Carroll, Sharp–Wentworth methods. Thermal degradation mechanistic model was also proposed by Phadnis–Deshpande method. In vitro antibacterial assay was analyzed for the synthesized compounds against various pathogenic bacterial strains such as Shigella sonnei, Escherichia coli, Klebseilla species, Staphylococcus aureus, Bacillus subtilis and Salmonella typhimurium species. From the assay, the ligand and its metal complexes possess commendable antibacterial activity and hence the synthesized compounds can act as potential antibacterial agents.

Solubility and Solution Thermodynamics of Some Sulfonamides in 1-Propanol + Water Mixtures

The solubilities of sulfadiazine (SD), sulfamerazine (SMR) and sulfamethazine (SMT) in some 1-propanol + water co-solvent mixtures were measured at five temperatures from 293.15 to 313.15 K over the polarity range provided by the aqueous solvent mixtures. The mole fraction solubility of all these sulfonamides was maximal in the 0.80 mass fraction of 1-propanol solvent mixture (δ solv = 28.3 MPa1/2) and minimal in water (δ = 47.8 MPa1/2) at all temperatures studied. The apparent thermodynamic functions Gibbs energy, enthalpy, and entropy of solution were obtained from these solubility data by using the van’t Hoff and Gibbs equations. Apparent thermodynamic quantities of mixing were also calculated by using the ideal solubilities reported in the literature. Nonlinear enthalpy–entropy relationships were observed for these drugs in the plots of enthalpy versus Gibbs energy of mixing. The plot of ∆mix H° versus ∆mix G° shows different trends according to the slopes obtained when the mixture compositions change. Accordingly, the mechanism for the solution process of SD and SMT in water-rich mixtures is enthalpy driven, whereas it is entropy driven for SMR. In a different way, in 1-propanol-rich mixtures the mechanism is enthalpy driven for SD and SMR and entropy driven for SMT. Ultimately, in almost all of the intermediate compositions, the mechanism is enthalpy driven. Nevertheless, the molecular events involved in the solution processes remain unclear.

Thermodynamic analysis of the interaction of partially hydrophobic cationic polyelectrolytes with sodium halide salts in water

Isothermal titration calorimetry was used to determine the temperature and concentration dependence of the enthalpy of mixing of 3,3- and 6,6-ionene fluorides, bromides, and iodides with low molecular weight salts (NaF, NaCl, NaBr, and NaI) in water. The magnitudes of the enthalpies, measured in the temperature range from 273 to 318 K, depended on the number of methylene groups on the ionene polyion (hydrophobicity), and on the anion of the added salt (ion-specificity). All enthalpies of mixing of 3,3- and 6,6-ionene fluorides with low molecular weight salts (NaCl, NaBr, and NaI) were negative, which is in contrast to the predictions of standard theories of polyelectrolyte solutions. This fact was interpreted in the light of the ion–water short-range interactions that are not accounted for in those theories. In contrast, the enthalpies of mixing of 3,3- and 6,6-ionene bromides and iodides with NaF were positive, being in accord with theory. Using the calorimetric data, we performed a model thermodynamic analysis of the polyelectrolyte–salt mixing process to obtain changes in the apparent standard Gibbs free energy, enthalpy, entropy, and heat capacity relative to the pure ionene fluorides in water. The results prove that halide ions replace fluoride counterions with a strength increasing in the order chloride < bromide < iodide. The process is enthalpy governed, accompanied by a positive change in the heat capacity.

Quantum Chemical Studies and Corrosion Inhibitive Properties of Mild Steel by Some Pyridine Derivatives in 1 N HCl Solution

The influence of 2,6-bis-(hydroxy)-pyridine (P1), 2,6-bis-(chloro)-pyridine (P2) and diethyl 1,1’-(pyridine-2,6-diyl)bis(5-methyl-1H-pyrazol2-3-carboxylate ( P3) on the corrosion of steel in 1 N HCl solution has been studied by weight loss measurements, potentiodynamic and impedance spectroscopy methods. The inhibiting action increases with the concentration of these compounds to attain 91,5% at 10 -3 M for P3. We note good agreement between gravimetric and electrochemical methods. The polarisation measurements show also that the pyridines act essentially as mixed inhibitors and the cathodic curves indicate that the reduction of proton at the steel surface happens with an activating mechanism. The temperature effect on the corrosion behaviour of iron in 1 M HCl without and with these inhibitors at different concentrations was studied in the temperature range from 313 to 353 K , and allows deducing the apparent activation energy, enthalpy and entropy of the dissolution process and the free energy were determined and discussed. The inhibitors were adsorbed on the iron surface according to the Langmuir adsorption isotherm model at different temperatures and some thermodynamic data for the adsorption process are calculated. The experimental study has been finished by quantum theoretical study; the quantum chemical calculations, based on DFT methods at B3LYP/6-31G** level of theory, were performed, by means of the GAUSSIAN 03 set of programs. Structural parameters, such as the frontier molecular orbital energies ( EHOMO

SYNTHESIS, CHARACTERIZATION AND THERMOGRAVIMETRIC STUDIES OF POLYMER RESIN DERIVED FROM 4-HYDROXYACETOPHENONE AND CATECHOL

A polymer (4-HACF) was synthesized by the polycondesation technique of 4-hydroxyacetophenone and catechol with formaldehyde in the presence of 2M HCl as a catalyst. A polymer has been characterized by UVVisible absorption spectra, Infra-red (IR) spectra and proton nuclear magnetic resonance ( 1 H NMR) spectra. The morphology of polymer was studied by scanning electron microscopy (SEM). The thermal decomposition behavior of polymer (4-HACF) was studied using thermogravimetric analysis in air atmosphere. Thermal decomposition curves are discussed with careful attention to minute details. The freeman-Carroll and Sharp-Wentworth methods have been used to calculate activation energy and thermal stability. Thermal activation energy (Ea) calculated with the help of these methods are in agreement with each other. Thermodynamic parameters such as free energy change (ΔF), entropy change (ΔS), Apparent entropy change(S*) and frequency factor Z are also determined on the

Ion-exchange Studies of Copolymer Derived from 4,4′-Biphenol

A novel copolymer resin (4,4′-BP-4,4′-ODA-F-II) has been synthesized by condensation polymerization reaction of 4,4′-biphenol and 4,4′-oxydianiline using the linkage of formaldehyde in presence of acid catalyst. The resin composition was determined on the basis of elemental analysis. Solution viscosity measurements in dimethylformamide were carried out to ascertain the characteristic functions and constants. The number average molecular weight was determined by conductometric titration in non-aqueous medium. The copolymer resin was further characterized by UV-Visible, Infra-red and Nuclear magnetic resonance spectroscopy to confine the most probable structure of synthesized copolymer. Thermal analysis was carried out for studying the thermal degradation behavior and kinetic parameters. Thermal degradation curve depicts four decomposition steps after a loss of water molecule and has been discussed with minute details by applying Freeman-Carroll, Sharp-Wentworth and Coat-Redfern equations to evaluate the kinetic parameters i.e., activation energy (Ea), order of reaction (n) and frequency factor (z). The data from Freeman-Carroll method has been used to determine various thermodynamic parameters i.e., entropy change (ΔS), free energy change (ΔF) and apparent entropy (S*). This copolymer is proved to be a selective chelating ion exchanger for certain metal ions such as Fe3+, Cu2+, Hg+2, Ni2+, Co2+, Zn2+, Cd2+ and Pb2+. A batch equilibrium method was employed in the study of selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the copolymer sample and a solution containing the metal ion. The study was carried out over a wide pH range, shaking time and in media of various ionic strengths.

Solubilities of 4-Bromo-1,8-naphthalic Anhydride in Different Pure Solvents and Binary Solvent Mixtures with the Temperature Range from (278.15 to 333.15) K

The solubilities of 4-bromo-1,8-naphthalic anhydride in organic solvents of acetone, methanol, ethanol, and acetic acid and in the binary mixtures of acetone and ethanol were determined over the temperature range of (278.15 to 333.15) K by using the analytical stirred-flask method. The solubilities of 4-bromo-1,8-naphthalic anhydride in these solvents increased with the increasing temperature. The experimental results showed that 4-bromo-1,8-naphthalic anhydride presents a higher solubility in acetone and the solubility in acetone had the strongest positive temperature dependency. The modified Apelblat equation, the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) equation, and the modified Jouyban–Acree model were proposed for correlating the experimental data. The values for the apparent molar enthalpy and entropy were calculated by using the van’t Hoff equation. The experiment results and correlation models could be useful in the reaction and purification process of 4-bromo-1,8-naphthalic anhydride.

Entropy of viscous Universe models

The cosmological event horizon entropy and the apparent horizon entropy of the ΛCDM and the Bianchi type I Universe model with viscosity has been calculated numerically, and analytically in the large time limit. It is shown that for these Universe models the cosmological event horizon entropy increases with time and for large times it approaches a finite maximum value. The effect of viscosity upon the entropy is also studied and we have found that its role is to decrease the entropy. The bigger the viscosity coefficient is the less the entropy will be. Furthermore, the radiation entropy for the ΛCDM Universe model with and without viscosity is investigated, and together with the cosmological event horizon entropy are used to examine the validity of the generalized second law of thermodynamics, which states that the total rate of change of entropy of the Universe is never negative, in this Universe model.

Solubility of glycine in binary system of ethanol + water solvent mixtures: Experimental data and thermodynamic modeling

The solubility of glycine in different compositions of ethanol–water binary solvent mixtures was measured over the temperature range of (278.15–328.15) K at intervals of 5.00K by employing an analytical stirred-flask method. The solubility data were fitted using the modified Apelblat equation and the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) equation, respectively. The modified Apelblat equation was found to regress the solubility data much better than the other two equations. The Van’t Hoff equation was used to calculate the apparent molar enthalpy and the apparent molar entropy of solution in the binary mixture solvent system, the dissolving process was endothermic and entropy-driving. The experiment results and correlation models could be used as essential data in the purification of glycine.

Determination and Correlation of Solubilities of (S)-Indoline-2-carboxylic Acid in Six Different Solvents from (283.15 to 358.15) K

The solubilities of (S)-indoline-2-carboxylilc acid (SIn2CA) in six pure solvents including water, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol were determined from (283.15 to 358.15) K at atmospheric pressure using the synthetic method. The solubility was determined by a laser monitoring observation technique and found to increase with the rise of temperature. The experimental solubilities were correlated by the modified Apelblat and λh (Buchowski) equations with the relative deviation less than 3.65% with the modified Apelblat equation and less than 0.023% with the λh equation. Thermodynamic functions of the solution of SIn2CA in different solvents including apparent dissolution enthalpy and entropy were obtained by van’t Hoff equation, and the apparent dissolution Gibbs free energy change was also calculated.

Thiazole‐Based Novel Terpolymer Ligand and Its Transition Metal Complexes: Thermal and Biological Studies

ABSTRACTA new terpolymer ligand involving 2‐amino‐6‐nitro‐ benzothiazole, melamine, and formaldehyde (BMF) has been synthesized in the presence of dimethyl formamide medium. The BMF ligand was characterized by elemental analysis and various spectral techniques like Fourier transform infrared (FTIR) spectroscopy, ultraviolet (UV)–visible spectroscopy, and 1H &amp; 13C nuclear magnetic resonance (NMR) spectroscopy to elucidate the structure and properties of the terpolymer ligand. The BMF metal complexes were prepared using the BMF ligand with some transition metal ions, such as Cu2+, Ni2+, and Zn2+ ions, in the presence of ethanol medium. The prepared complexes have been characterized by elemental analysis and FTIR, electronic, electron spin resonance, and 1H &amp; 13C NMR spectral studies. The molecular weight of the BMF ligand and its metal complexes was determined by gel permeation chromatography. The surface features and crystalline behavior of the ligand and its complexes were analyzed by scanning electron microscope (SEM) and X‐ray diffraction (XRD) methods. Thermal stability of the ligand and its metal complexes was studied by thermogravimetric analysis (TGA). Kinetic parameters such as activation energyand order of reaction (n), and thermodynamic parameters namely entropy change, free energy change, apparent entropy, and frequency factor were calculated using Freeman–Carroll, Sharp–Wentworth, and Phadnis–Deshpande (PD) methods. Thermal degradation model of the terpolymer ligand and its metal complexes was also proposed using the PD method. The antibacterial activities of the BMF ligand and its metal complexes were checked against chosen microbes such as Shigella sonnei, Escherichia coli, Klebsiella species, Staphylococcus aureus, Bacillus subtilis, and Salmonella typhimurium. © 2013 Wiley Periodicals, Inc. Adv Polym Technol 2013, 32, 21376; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21376

Feedback cooling, measurement errors, and entropy production

The efficiency of a feedback mechanism depends on the precision of the measurement outcomes obtained from the controlled system. Accordingly, measurement errors affect the entropy production in the system. We explore this issue in the context of active feedback cooling by modeling a typical cold damping setup as a harmonic oscillator in contact with a heat reservoir and subjected to a velocity-dependent feedback force that reduces the random motion. We consider two models that distinguish whether the sensor continuously measures the position of the resonator or directly its velocity (in practice, an electric current). Adopting the standpoint of the controlled system, we identify the ‘entropy pumping’ contribution that describes the entropy reduction due to the feedback control and that modifies the second law of thermodynamics. We also assign a relaxation dynamics to the feedback mechanism and compare the apparent entropy production in the system and the heat bath (under the influence of the controller) to the total entropy production in the super-system that includes the controller. In this context, entropy pumping reflects the existence of hidden degrees of freedom and the apparent entropy production satisfies fluctuation theorems associated with an effective Langevin dynamics.

Postmenopausal women with osteoporosis and osteoarthritis show different microstructural characteristics of trabecular bone in proximal tibia using high-resolution magnetic resonance imaging at 3 tesla

BackgroundOsteoporosis (OP) and osteoarthritis (OA) are two common musculoskeletal disorders that affect the quality of life in aged people. An inverse relationship between OP and OA was proposed four decades ago. However, the difference in microstructure of the trabecular bone of these two disorders by high-resolution MRI (HR-MRI) has not been compared. The primary objective of the study is to explain the actual relationship between OA and OP based on differences between bone microstructure of these two diseases. The secondary objectives are to find out the significance of Euler number and its relationship with other structural parameters, and important role of HR-MRI to reveal the microstructure of trabecular bone directly.MethodsTotally, 30 women with OP and 30 women with OA (n = 60) were included in this study. Primary OA of hip, knee, as well as spinal arthrosis were diagnosed according to plain X-ray film findings. Osteoporosis was defined based on the latest criteria of World Health Organization (WHO). Structural and textural parameters derived from HR-MRI images of proximal tibia were calculated and compared with special software.ResultsThere were significant differences in apparent bone volume fraction, trabecular thickness, mean roundness, Euler number, entropy and inverse different moment between OP and OA patients. In OP group, apparent trabecular separation (Tb.Sp), inertia, absolute value and contrast were positively correlated with Euler number, whereas apparent trabecular number (Tb.N), mean trabecular area, inverse difference and inverse different moment were negatively correlated. Apparent trabecular bone volume fraction (BV/TV), mean trabecular area, mean trabecular perimeter and mean skeleton length negatively correlated with Euler number in OA group. Inverse different moment was the texture parameter, which influenced bone mineral density (BMD) of femoral neck, meanwhile contrast influenced BMD of both great trochanter and Ward’s triangle in OP group. While in OA group, Euler number was the exclusive parameter, which affected BMD of femoral neck and Ward’s triangle.ConclusionsWe found significant differences in microstructure parameters derived from HR-MRI images between postmenopausal women with OP and OA. It convincingly supports the hypothesis that there might be an inverse relationship between OP and OA.

Solubilities of p-coumaric and caffeic acid in ionic liquids and organic solvents

The solubilities of two cinnamic acid derivatives, namely p-coumaric acid and caffeic acid, in six 1-alkyl-3-methyl imidazolium based ionic liquids composed of the PF6−, BF4−, TFO− and TF2N− anions, and in two organic solvents, t-pentanol and ethyl acetate, have been measured at the temperature range of about (303 to 317)K. The p-coumaric acid was found to be more soluble than caffeic acid in all studied solvents. Higher solubilities of both acids were observed in the ionic liquids composed of the BF4− and TFO− anions. The increase of the alkyl chain length on the cation invokes a decrease in solubility in the case of hydrophilic ionic liquids composed of BF4− anion, while in the case of hydrophobic ones composed of PF6− anion an increase in the solubility is observed. Between the two organic solvents t-pentanol is better solvent than ethyl acetate for both acids. Moreover, using the van’t Hoff equations the apparent Gibbs energy, enthalpy, and entropy of solution were calculated. Finally, successful correlation of the experimental data was achieved with the UNIQUAC and the NRTL activity coefficient models, while poor predictions of the solubility of the two acids in the organic solvents were obtained with two UNIFAC models.

Solubility of puerarin in the binary system of methanol and acetic acid solvent mixtures

The solubility of puerarin in methanol and acetic acid solvent mixtures was measured by a static analytical method at temperatures ranging from (293.15 to 333.15)K. The mass fraction of acetic acid in the solvent mixtures (w3) ranges from 0 to 0.6. The Apelblat equation was applied for correlating the experimental solubility data, and subsequently used to derive the apparent molar enthalpy, Gibbs energy, and entropy of dissolution of puerarin in methanol+acetic acid binary mixtures.

Solvent Extraction Equilibrium of Zinc from Nitrate Solutions with 2-Ethylhexylphosphonic Acid Mono-2-ethylhexyl Ester

The solvent extraction equilibrium of zinc with 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA) in an alkane diluent, Shellsol D70, was studied at a constant ionic strength of 1 mol/L from nitrate solutions considering the correction of the extractant nonideality in the organic phase by Alstad’s method. On the basis of the slope analysis of the obtained data, a molar ratio of 1:2 for the zinc to the EHPNA dimer in the extracted complex was indicated. Apparent extraction equilibrium constants obtained at each temperature from 283 to 323 K showed the endothermic nature of the extraction reaction and gave the apparent standard enthalpy and entropy changes. These two constants enable the calculation of the zinc distribution ratio at each temperature which correlates the experimental data with good accuracy.

Synthesis, Thermal and Electrical Properties of 2, 2’-HBBF Copolymer Resin

The copolymer (2, 2'-HBBF) synthesized by the condensation of 2, 2'-dihydroxybiphenyl (2, 2'-HB) and biuret (B) with formaldehyde (F) in the presence of acid catalyst using 1:1:2 molar proportions of the reacting monomers. The thermogravimetric analysis of copolymer resin prepared in the present study has been carried out by non-isothermal thermogravimetric analysis technique in which sample is subjected to condition of continuous increase in temperature at linear rate. The advantage of Freeman-Carroll method is to calculate both the order of reaction (n) and energy of activation in one single stage by keeping heating rate constant. By using data of thermogravimetric analysis, various thermogravimetric parameters like frequency factor (Z), entropy change (ΔS), free energy change (ΔF) and apparent entropy (S*) have been determined using Freeman-Carroll method. The electrical properties of 2, 2'-HBBF copolymers were measured over a wide range of temperature (303-423 K). From the electrical conductivity of these copolymers, activation energies of electrical conduction have been evaluated and values lies in the range 3.01x10 -20 - 6.43x10 20 J/K. On the basis of above studies, these copolymers can be ranked as semiconductors.

Combined Density Functional Theory and Monte Carlo Analysis of Monomolecular Cracking of Light Alkanes Over H-ZSM-5

Density functional calculations applying periodic boundary conditions have been performed to investigate adsorption and cracking of light alkanes (C3–C6) on zeolite H-ZSM-5. Intrinsic energy barriers were obtained from single-point calculations by applying the revised form of the PBE functional (RPBE) to structures optimized on the PBE potential energy surface. Dispersion interactions were accounted for by adding a damped dispersion term to the PBE energies. The dependence of the adsorption enthalpy on the carbon number is in agreement with experimental observation. From intrinsic energy barriers, intrinsic rate coefficients were calculated by means of transition state theory. The dependence of the intrinsic enthalpy and entropy of activation on the carbon number is discussed and compared to experimental observations. Transition path sampling was employed to unravel qualitatively the reaction mechanism for cracking of butane. Monte Carlo simulations in the canonical ensemble were conducted to estimate the temperature dependence of the adsorption enthalpy and entropy of propane to n-hexane. These quantities are not constant, as is often assumed in the interpretation of experimental data but become less negative with increasing temperature. It is shown how the selection of adsorption parameters influences the extraction of intrinsic rate parameters from experimental rate data. Based on the present analysis, an alternative partitioning of the experimentally accessible apparent entropy of activation into contributions from adsorption and intrinsic reaction is proposed.

Influence of temperature and background electrolyte on the sorption of neptunium(V) on Opalinus Clay

The temperature dependence of the sorption of 8μM neptunium(V) on Opalinus Clay (OPA, Mont Terri, Switzerland) was investigated between 40 and 80°C and compared to previous results for 20°C. The batch experiments were performed under ambient air conditions in synthetic pore water (pH=7.6, I=0.4M) under variation of the solid-to-liquid ratio between 2 and 20g/L. Under these conditions the sorption of Np(V) on OPA was found to be an endothermic process as the average distribution coefficient (Kd) increases continuously with increasing temperature from 23±4L/kg at 40°C to 678±254L/kg at 80°C. In the temperature range of 40-80°C, the plot of log(Kd) vs. 1/T could be fitted to the Van't Hoff equation delivering an apparent sorption enthalpy of 80±16kJ/mol and an apparent sorption entropy of 278±48J/K·mol.Since pore water consists of several constituents (mainly NaCl, CaCl2, and MgCl2), additional batch experiments were performed at room temperature to investigate the influence of 0.1 and 0.4M NaClO4, NaCl, CaCl2, and MgCl2 electrolytes on the sorption of Np(V) on OPA at pH 7.6. The results showed significant differences between monovalent (Na+) and divalent (Mg2+, Ca2+) electrolytes. While the sorption isotherms in sodium electrolytes (I=0.4M) provided Kd values of 231±13 (NaClO4) and 224±17L/kg (NaCl), low distribution coefficients of 54±6L/kg (MgCl2, I=0.1M) and less were determined in magnesium and calcium electrolytes. A weak dependence on ionic strength was observed only in the batch experiments using NaClO4 as electrolyte. In all other electrolytes the influence of ionic strength on the sorption of Np(V) was negligible between I=0.1 and 0.4M.

Studies of new oligomer–metal complexes and their antibacterial activities

AbstractA new oligomeric ligand was synthesized from anthranilic acid and 2‐aminopyridine with formaldehyde using a condensation technique in the presence of acid medium. Oligomer–metal complexes were prepared involving transition metal ions Cu(II), Mn(II) and Zn(II) using the synthesized oligomer as ligand. The oligomeric ligand and its metal complexes were characterized using various spectral techniques such as Fourier transform infrared, electronic, electron spin resonance, 1H NMR and 13C NMR. Gel permeation chromatography was used to determine number‐, weight‐ and size‐average molecular weights of the oligomeric ligand. The surface characteristics and nature of the oligomeric ligand and its metal complexes were examined using scanning electron microscopy and X‐ray diffraction analysis. The thermal properties and degradation behaviour of the oligomeric ligand and its complexes were investigated using thermogravimetric analysis. Kinetic and thermodynamic studies of the ligand and its metal complexes were carried out using Freeman–Carroll (FC) and Sharp–Wentworth (SW) methods. From the thermogravimetric data, kinetic and thermodynamic parameters such as activation energy, order of reaction, entropy change, apparent entropy, frequency factor and free energy change were calculated. The activation energy was further calculated from the Phadnis‐Deshpande (PD) method and the degradation mechanism for the thermal decomposition reaction is proposed. The activation energy calculated from the FC and SW methods was in good agreement with that calculated from the PD method. The oligomeric ligand and its metal complexes were screened for antibacterial activity. It was found that the synthesized compounds were potent antibacterial agents. © 2012 Society of Chemical Industry