Recent Progress in Chemical Science Research Vol. 6

Systematic research has been done on lattice relaxation on wurtzite GaN microdisks produced by plasma-assisted molecular beam epitaxy. High-resolution transmission electron microscopy was used to assess the lattice constants of GaN microdisks. The anisotropic strain was analyzed by the microscopic atomic layers of GaN microdisks. We learned that the lateral lattice strain along a-axis followed a linear relation during the epi-growth, while the vertical lattice strain with c-axis exhibited a quadratic deviation.

Structural-parametric model, decision linear ordinary second-order differential equation, parametric structural schematic diagram, transfer functions of the electroelastic actuator of mechatronics systems for nanoscience are obtained. Effects of geometric and physical parameters of the piezoactuator and the external load on its dynamic characteristics are determined. The parametric structural schematic diagram and the transfer functions of the piezoactuator for the transverse, longitudinal, shift piezoelectric effects are obtained from the structural-parametric model of the piezoactuator. For calculation of the control systems for nanotechnology with the piezoactuator its the parametric structural schematic diagram and the transfer functions are determined. The generalized parametric structural schematic diagram of the electroelastic actuator is constructed.

Artocarpus species contain a high concentration of phenolic compounds, such as flavonoids, stilbenoids, and arylbenzofurons. Furthermore, compounds from Artocarpus species demonstrated antibacterial, antitubercular, antiviral, antifungal, antiplatelet, antiarthritic, tyrosinase inhibitory, and cytotoxic properties. However, there has been no phytochemical research on Artocarpus odoratissimus from Sarawak. As a result, it would be intriguing to create a chemical profile of such Sarawakian species. Various chromatographic methods, including liquid vacuum chromatography, radial chromatography, and column chromatography, were used to isolate the chemical constituents of Artocarpus odoratissimus' root, bark, and leaves. The leaves can also be used to heal ulcers and burn.  The isolation and purification using different solvents system ratio of hexane and ethyl acetate (10:0, 8:2, 6:4, 4:6, 2:8, 0:10) and ethyl acetate and methanol (8:2) have led to two flavonoids; pinocembrin (1) and pinostrobin (2), and six triterpenoids; \(\alpha\)-amyrin acetate (3), \(\beta\)-amyrin acetate (4), traxateryl acetate (5), hexyl dodecanoate (6), \(\beta\)-sitosterol (7) and stigmasterol (8). The structures (1) – (8) were elucidated using various spectroscopic analyses, which included Mass Spectroscopy (MS), Infrared (IR) spectroscopy, Ultra-violet (UV) spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy, as well as by comparison with the reported data. Although the presence of compounds 1 and 2 was prevalent across a wide range of plant species, it was rare in Artocarpus species, which may have chemotaxonomic implications for the genus Artocarpus.

In the title compound, C₁₃H₁₅NO₂, the fused non-aromatic rings of the julolidine moiety incorporate envelope conformations. In order to create a S(6) ring motif, the hydroxy group establishes an intramolecular hydrogen connection with the aldehyde O atom. Weak intermolecular C—H O hydrogen bonds help to stabilize the crystal structure. The molecular structure of a solid-state compound is obtained experimentally and compared to optimal density functional theory (DFT) structures at the B3LYP/6-311 G(d,p) level. The different intermolecular interactions and the crystal packing strength of the compound have been determined by Hirshfeld surface analysis. To study the stability of the molecule and recognize the dominant energy type, energy frameworks were constructed, using various intermolecular interaction energies.

An accurate, simple and precise RP-HPLC method with photodiode array detector (PDA) for the simultaneous determination of ambroxol, roxithromycin and serratiopeptidase in bulk and in pharmaceutical dosage form was developed and validated. The three drugs were separated and estimated using Waters HPLC system and YMC Pack pro C18 (250 × 4.6 mm) 5 \(\mu\)m particle size column. The mobile phase consisted of 0.1% orthophosphoric acid and acetonitrile (60:40 v/v). The calibration curves were linear over concentration range of 12-36 \(\mu\)g/mL, 60-180 \(\mu\)g/mL and 6-18 \(\mu\)g/mL with limits of detection of 0.040 \(\mu\)g/mL, 1.176 \(\mu\)g/mL and 0.127 \(\mu\)g/mL for ambroxol, roxithromycin and serratiopeptidase, respectively. Recovery varied in range of 99.57% - 100.24% with relative standard deviation ranging from 0.12% to 0.36% for the current drugs. The proposed method was found to be appropriate for the quality control of ambroxol, roxithromycin and serratiopeptidase simultaneously in a bulk drug as well as in pharmaceutical dosage forms.

The inhibitory impact of extracts from the leaves and stem of Salvodera persica and Solanum xanthocarpum on the corrosion of aluminium in a 2N HCl solution was assessed using gasometric and weight loss methods. The findings showed that the corrosion inhibition efficiency increased on increasing plant extract concentration. Green inhibitors adsorb on the surface to form protective film which displace water and protect it against deteriorating. Effective organic corrosion inhibitors contain nitrogen, oxygen, sulfur and phosphorus with lone electron pairs as well can contain structural moieties with \(\pi\)-electrons that interact with metal favoring the adsorption process. The percentage inhibition efficiencies obtained through weight loss were reasonably consistent with those obtained through the gasometric method. Data analysis reveals that the combating efficacy of Salvodera persica outperforms that of Solanum xanthocarpum. However, Salvodera persica leaves extract outperforms Salvodera persica stem extract in terms of combating power. Plant extract can be considered as promising industrial resource for protection of metals due to their environmental acceptability, readily availability and nontoxic nature.

Synthesis of thiazoles by the base induced cyclization of active methylene isocyanides with dithioesters, xanthate esters, \(\alpha\)-oxodithioesters and 2-oxo-2-(amino) ethanedithioates are presented in this chapter. Besides, a tandem approach for the synthesis of oxazoles is developed by the oxidation of alcohols and arylmethyl bromides followed by cyclization with activated methylene isocyanides is also illustrated. In the same way, synthesis of oxazoles by the reaction of tosyl chloride with carboxylic acids followed by cyclization with tosylmethyl isocyanide (TosMIC) in the presence of a base is described. Finally, synthesis of imidazoles by the cyclization of TosMIC and ethyl isocyanoacetate with N(N), N'-di(tri)substituted carbamimidothioates is also presented. The probable mechanisms for the formation of azoles (thiazoles, oxazoles and imidazoles) are also given in this chapter.    

The quantitative aspects of the oxidation of phenols to the corresponding quinones have been studied and reported in literature but there are few reports of the kinetic, thermodynamic and mechanistic studies of the oxidation of phenols.This chapter deals with the oxidation of some perfumery phenols found in Indian spices by a variety of inorganic and organic oxidants using kinetic methods.

The oxidation of the perfumery isomeric phenols, Eugenol (4-Allyl-2-methoxy phenol) and Isoeugenol (2-Methoxy-4(prop-1-en-1-yl) phenol) has been carried out using 1) inorganic oxidants,KBrO₃,KIO₃ and K₂S₂O₈ in acidic medium and 2)N-Bromosuccinimide and Sodium chloro(4-methylbenzene-1-sulfonyl)azanide (Chloramine T) in alkaline medium.These phenols are found in the Indian spices,clove (Syzygium aromaticum), nutmeg (Myristicafragrans), Cinnamon (Cinnamomum zeylanicum) and Basil (Tulsi) (Ocimum basilium) and are used in the manufacture of perfumes,fragrances and flavouring agents.

The oxidation was studied under first order kinetic conditions with respect to the oxidant ie.[oxidant]<<[phenol].For both the phenols studied,the oxidation rate increased with phenol concentration but decreased with oxidant concentration.The sequences of oxidation rates of the phenols for the different oxidants has been explained on the basis of their steric factors,isomeric and structural features. From the variation of oxidation rate with temperature, the energy of activation and other thermodynamic activation parameters were evaluated and interpreted in terms of the molecular dynamics of the oxidation process.Suitable reaction mechanisms have been suggested for the oxidation of the phenols under study.

Smaller molecules with crystalline and spherical morphologies have diverse applications. When working with nanomaterials, determining the particle size is necessary and crucial. The key topic of research is information on a                        variety of physical attributes, such as size, morphology, surface texture, roughness, and chemical composition of materials. Furthermore, sophisticated sample manipulation techniques used in SEM investigations can yield important details about the crystal morphology at the micro- and nanometer scales.

In order to understand the conductivity and surface shape of the cathode, it is crucial to understand the electrochemical reduction of nitro aromatic compounds to their amine derivative. The measurement of the variation of current and electrode potential with time during the electrolysis is also the important area of research. The biological activity of a nitro aromatic molecule is increased by the particle size variation in the reduction product. The investigation of the biological activity of organic molecules before and after electrolysis is an intriguing topic in the pharmaceutical industry.

In DMS materials, magnetic ions replace a very small portion of the host semiconductor cation. We selected the transparent ZnO, which has a bandgap of 3.3 eV at ambient temperature, as the semiconducting host. Studies on 3d transition metal-doped ZnO showed that the magnetic moments were quite tiny. We looked into ZnO thin films doped with rare earth (RE) metal ions in light of more recent Gd in GaN studies that showed large magnetic moments. The 3d electrons in transition metals are exterior and delocalized, resulting in strong direct exchange interactions and high Curie temperatures, but the orbital momentum is often zero, resulting in small total magnetic moments per atom. The 4f electrons are localised in RE metals, and exchange interactions are indirect, via 5d or 6s conduction electrons, but the elevated orbital momentum leads to high total magnetic moments per atom, such as 3.27µB for Nd. Nd has a Curie point of 19 K. The findings of our investigation into Nd-doped ZnO films are presented in this work. In order to learn more about the electrical characteristics of films, hall measurements are used. Here, we made and examined ZnO films doped with various Nd concentrations. On a-plane Al2O3 or SiO2 substrates, the films are grown. Hall investigations of electrical properties revealed the presence of a degenerate, highly conducting, film–substrate interface layer for the films grown on Al2O₃; such an effect can be avoided, for example, by using SiO₂ substrates. No anomalous Hall effect was seen in the magnetotransport experiments, but there was a strong negative magneto resistance ratio, which can be explained by the system's paramagnetic reaction to the applied magnetic field. We want to keep using surface-sensitive methods to examine the magnetic characteristics of ZnO:RE thin films.