Current Physical Chemistry - Volume 11, Issue 1, 2021

Background: Carry out an in silico study of chemical substances isolated from the species: Drimys angustifolia and Drimys brasiliensis. Methods: A theoretical study of global reactivity, QSAR descriptors, MEP construction and molecular docking was performed to analyze the interaction of substances with acetylcholinesterase of Drosophila melanogaster and the prediction of skin permeation and toxicological properties of the substances. Results: Chemical reactivity and molecular stability investigation suggest that the substance which presents stability values similar to the standard substance D-limonene, was Terpinen-4-ol. The MEPs of the investigated substances were evenly distributed along the hydrogens and oxygens. The molecular docking studies suggest interesting and promising results for the substance Myristicin. Regarding skin permeability, the results suggests low skin absorption for all substances. Regarding toxicological properties, bicyclogermacrene indicated non-carcinogenic and mutagenic activity. Conclusion: Our results suggest that the substance, bicyclogermacrene, is a potential candidate for usage as a repellent.

Aims: To develop an efficient protocol, which involves an exploration of the catalytic potential of both the room temperature and surfactant ionic liquids towards the synthesis of biologically important derivatives of 2-aminothiazole. Objective: Specific heat capacity data as a function of temperature for the synthesized 2- aminothiazole derivatives has been advanced by exploring their thermal profiles. Methods: The thermal gravimetry analysis and differential scanning calorimetry techniques are used systematically. Results: The present strategy could prove to be useful for researchers working in the field of surfactants and surfactant-based ionic liquids towards their exploration in organic synthesis. In addition to that, the effect of electronic parameters on the melting temperature of the corresponding 2-aminothiazole has been demonstrated with the help of thermal analysis. Specific heat capacity data as a function of temperature for the synthesized 2- aminothiazole derivatives has also been reported. Conclusion: Melting behavior of the synthesized 2-aminothiazole derivatives is to be described on the basis of electronic effects with the help of thermal analysis. Additionally, the specific heat capacity data can be helpful for the chemists, those engaged in chemical modelling as well as docking studies. Furthermore, the data also helps to determine valuable thermodynamic parameters such as entropy and enthalpy.

Aim: To study the specific heat capacity for biologically and medicinally important compounds, namely, lidocaine hydrochloride, clove oil and beta-Piperine using the DSC technique. Background: One of the main problems in the science of medicine is the application of drug molecules with limited solubility in water and in biofluids. Solubility is related to the chemical potential of the solutes involved, which imparts free energy avenues, a necessary requirement for equilibrium processes. The convincing solutions for solving this issue are the utilization of ionic liquids as a drug. Lidocaine is the most widely utilized intraoral injected dental anesthetic prior to performing painful medical procedures. Besides that, lidocaine hydrochloride is a salt, having a melting point of 76°C (349 K) and behaves as an ionic liquid after melting. Clove oil and β-piperine are very well-known naturally occurring medicinal compounds having a broad spectrum of applications. Objective: To study the thermal gravimetry analysis behaviour for lidocaine hydrochloride, clove oil and β-piperine. To compute specific heat capacity at constant pressure, as a function of temperature for the studied systems. Methods: In the present communication, the studies of Thermal Gravimetry Analysis (TGA) and Differential Scanning Calorimetry (DSC) for these compounds are described. Results: The data of heat flow have been utilized to obtain specific heat capacity (Cp) values for lidocaine hydrochloride, clove oil and β-piperine over a temperature range between 75°C (348 K) and 155°C (428 K) based upon the methodology we have developed. Conclusion: LC•HCl behaves as an ionic liquid between 76 and 230°C (349 and 503 K). Clove oil shows lower specific heat capacity values and is similar to other organic aromatic compounds while piperine exhibits comparative high specific heat capacity values indicating possibilities of intramolecular hydrogen bonding, which is generally not affected by temperature.

Background: The spread of bacterial infections has become a growing concern to human beings particularly in the medical and food packaging industry. Such infection may also result due to the adhesion of microbes from the environment. Polyvinyl chloride is a versatile polymer used in medical devices and food packaging materials, need to be modified to enhance antibacterial activity. Objective: The main focus of the present work was to prepare polymer nanocomposite based on polyvinylchloride to prevent bacterial infections. Method: Polyvinyl chloride/Polyester/bentonite clay composite films were prepared using the solution casting method. The morphological properties of synthesized nanocomposite films were studied using XRD, SEM, and AFM, whereas biological activity is evaluated by bacterial adhesion study. Results: The results showed that intercalation of clay present in nanocomposite films and SEM analysis showed agglomeration of clay material due to high filler loading. The antibacterial adhesion study showed the antibacterial activity of polymer nanocomposite films, which is further confirmed by surface roughness values by AFM study. Conclusion: Our result showed that such polymer nanocomposite films were useful in medical and food packaging applications.

Aim: The micellization behavior of cationic surfactants has been studied in the presence of food additives. Objectives: Micellization behaviour of cationic surfactants, Cetyltrimethylammonium Bromide (CTAB) and Tetradecyltrimethylammonium Bromide (TTAB) has been studied in water and in various concentrations of salts (food additives) L-glutamic acid, sodium propionate, sodium citrate tribasic dihydrate and disodium tartrate dihydrate at (298.15, 308.15 and 318.15) K. Methods: Two methods used in the present study are specific conductance measurements and spectroscopy (NMR) studies. Results: From the specific conductance(Κ), various parameters such as Critical Micelle Concentration (CMC), degree of ionization of micelle (α), standard Gibbs free energy (ΔG°m), enthalpy (ΔH°m), and entropy (ΔS°m) of micellization have also been calculated. Thermodynamic parameters related to the micellization process were also analyzed through NMR studies. Conclusion: The CMC values are influenced by the presence of food additive. The magnitude of CMC values increases with an increase in the concentration of food additive. In all the cases, enthalpy of micellization, ΔH°m values are found to be negative, whereas entropy of micellization, ΔS°m values are positive, which indicates that hydrophobic interactions play a major role in the micellization process. Moreover, NMR studies reveal that tartrate and citrate are more hydrated than glutamic acid and propionate, resulting in a more downfield shift.

Background: Thermoelectric material with high performance and low cost is the basic need of today. Bismuth selenide is a thermoelectric material. A set of bismuth selenide thin films having different stoichiometry ratios varying Bi/Se ratio from 0.123 to 0.309 have been prepared. Objective: The present work deals with the synthesis and characterization of various thin films of bismuth selenide. The thermoelectric properties of thin films were also investigated. The aim of this work is to investigate the effect of composition ratio on the structural and thermoelectric properties and to find out the best stoichiometry ratio of bismuth selenide thin films that can be used in the application of thermoelectric devices. Methods: A set of bismuth selenide thin films having different elemental compositions were prepared by employing the thermal evaporation technique. The crystal structure and elemental composition of thin films were investigated by XRD and EDAX, respectively. The roughness of films was analyzed by AFM. The thermoelectric properties of various thin films were also measured. Results: XRD spectrum confirms the formation of phases formed in thin films which slightly matched with standard data. AFM results indicated that the surface of films was smooth and nanoparticles were generated on the surface. AFM results indicated that the surfaces of annealed thin films were smoother than as-deposited thin films. Seebeck coefficient was found negative throughout the temperature range. The power factor was also calculated by the Seebeck coefficient and results revealed the effect of composition ratio on Seebeck coefficient, electrical conductivity, and power factor. Thin films having a composition ratio of 0.182 exhibited the highest power factor. Conclusion: This study provides relevant basic information on the thermoelectric property of thin films, as well as presents the effect of compositional variation on thermoelectric measurements. From the application point of view in the thermoelectric devices, the best stoichiometric thin films out of four prepared thin films have been presented.

Aims: CdS nanoparticles are an attractive material having applications in various fields like pigment in paints, biotag for bioimaging and many more optoelectronic as well as biological applications. The present study aims to synthesize and characterize the CdS nanoparticles to make it applicable in different areas. Objectives: Preparation of CdS nanoparticles by using simple and facile chemical methods and further physical and structural characterization using various physical tools. Methods: In present work, CdS nanoparticles have been synthesized by using a rationally simple chemical precipitation method with some modification on temperature and incubation time in existed methods. Characterizations were done by employing XRD, SEM, TEM and AFM techniques. Results: Simple chemical method produces the CdS nanoparticles with a size of about 100- 200 nm in length and 5-10 nm in diameter. The SEM studies show that the CdS nanoparticles can agglomerate and form a continuous network-like structure. The X-Ray Diffraction (XRD) measurements show the single-phase formation of CdS nanoparticles with the structure of the cubic phase, and the broadening of XRD patterns indicates that the prepared samples are nanostructured. Our analysis of CdS nanoparticles by using a transmission electron microscope and Atomic Force Microscope (AFM) revealed that the nanoparticles form both spherical and nearly rod-shaped with the average size applicable for biotagging. UV-Vis spectroscopic analysis reveals a blue shift in the absorption peak probably caused by quantum confinement. Conclusion: The observed CdS nanoparticles were appeared yellow in color. The XRD pattern of the CdS nanoparticles showed that the materials were of nanometric sized regime with a predominantly cubic phase along with the rod and round morphology. The study and characterization of CdS nanoparticles will bring us a new approach to understand the biological problem by tagging nanoparticles with biomolecules and further suggest that the CdS nanoparticles formulate it more suitable biocompatible nanomaterial for biotagging and bioimaging.