Advanced Journal of Chemistry, Section A
Volume:4 Issue: 1, Winter 2021

In the present study, water soluble 5, 17-bis[(N-methylglucamine)methyl]-25,26,27,28-tetrahydroxycalix[4]arene (3, as a highly efficient excipient material) was synthesized to immobilize α-amylase first time using the N-methylglucamine functionalities for excipient-enzyme complex formation at its para-positions. The excipient-α-amylase complex (4)was used for the starch degradation. The optimum apparent activity of 4 was determined at variable conditions such as the effect of pH (7.0), temperature (25°C) and initial concentration of enzyme (15 µL). Under such optimized parameters, the maximum 71% yield of enzyme was immobilized onto the functionalized calix[4]arene material (3). The catalytic properties of 4 were determined by comparing with free α-amylase. The complex 4 revealed high stability under sever conditions, i.e. high temperature and offers multiple reuses with little loss in enzyme activity due to higher α-amylase concentration has been protected by complex. In addition, the enzyme activity and the excipient-α-amylase complex were found to have extra characteristics as compared to the free α-amylase for starch hydrolysis with respect to its stability and reusability. These advantageous characteristics and low cost of material from which calixarene derivative was prepared, making it economically viable for starch degradation on industrial scale.

Antibiotic-resistant pathogenic bacteria (e.g., multi-drug resistant bacteria, MDR) have been one of the major threats to human health. Nanoparticles, the newly emerging tools, hold the promise to solve the antibiotic resistance-related problems. This study aimed at evaluating the antibacterial activities of Ca-doped ceria nanoparticles (CDC) against the Gram-negative bacteria (Pseudomonas aeruginosa and Klebsiella pneumoniae) and Gram-positive bacteria (Staphylococcus aureus) using optical density measurement. Co-precipitation method was used to synthesize the Ca-doped ceria nanoparticles with and without addition of cetyltrimethylammonium bromide (CTAB, cationic surfactant). The prepared nanoparticles were characterized using the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV-Vis spectroscopy. The XRD results demonstrated that, the CDC-CTAB nanoparticles (synthesized via CTAB-assisted co-precipitation method) had the smaller crystallite size (16.26 nm) and higher specific surface area (56.72 m2/g) compared to the CTAB-free synthesized sample (CDC nanoparticles). In addition, the CDC-CTAB nanoparticles exhibited a better inhibition percentage of bacteria growth (29.54-34.08%) against both the Gram-negative and Gram-positive bacteria. In terms of materials cost and toxicity, Ca-doped ceria nanoparticles can be considered as promising materials and, their biological activity might be evaluated against other microorganisms.

In this work, thioridazine (TR) as an important neuroleptic drug has been detected simply by an electrochemical approach using a glassy carbon electrode modified by nickel oxide nanoparticles decorated graphene quantum dot (NiO/GQD/GCE). The bare and modified electrodes were characterized using the scanning electron microscope (SEM) and electrochemical techniques. The cyclic voltammetric studies demonstrated that the NiO/GQD/GCE has remarkably enhanced electro-catalytic activity towards the oxidation of TR in neutral solutions. The results (significant increase in peak current and a negative shift in TR oxidation potential) are related to the increase in electrode surface area and electron transfer rate along with the modifier catalytic role. The NiO/GQD modified electrode used for sensitive determination of TR by differential pulse voltammetry (DPV) method. The effect of experimental parameters on the obtained results was studied and optimized. The NiO/GQD/GCE modified electrode revealed a linear response in the concentration range from 2×10-9 to 200×10-9 M with a limit of detection (LOD) equal to 0.05×10-9 M (S/N=3). The sensor was applied to determine TR in serum and pharmaceutical samples, which proves this sensor is an ideal device for TR determination.

In this work, the MgZnAl-LDH/Zeolite Y and (MgZnAl-LDH+MgFe2O4)@SiO2 composites based on layered double hydroxide (LDH) were synthesized and characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX) analysis. The efficiency of the samples was assessed for simultaneous removal of cationic and anionic dyes from the solution. In this work, methylene blue and methyl orange as cationic and anionic dyes were used. The performance of prepared composites was also compared with their components. The results demonstrated that the Zeolite Y sample could only remove the methylene blue dye from the solution. The MgFe2O4 sample is not able to remove any of the anionic and cationic dyes. The simultaneous removal of the methylene blue and methyl orange dyes is observed by the MgZnAl-LDH sample. The MgZnAl-LDH/Zeolite Y and (MgZnAl-LDH+MgFe2O4)@SiO2 composites revealed similar performance to the MgZnAl-LDH. Moreover, the MgZnAl-LDH@SiO2 composite showed lower efficiency compared with that of the MgZnAl-LDH. In addition, different kinetic models including, the pseudo-first-order, pseudo-second-order, and particle diffusion models were examined for the simultaneous removal of dyes. The kinetic data revealed the adsorption process could be well fitted by the pseudo-second-order kinetic model. The methylene blue dye removal by (MgZnAl-LDH+MgFe2O4)@SiO2 sample occurred by the adsorption on the surface and intra-particle diffusion.

In the present study, the complete structural and vibrational analysis of 3-methyle-4-(4-nitrophenyl)-4,8-dihydropyrazolo[4',3':5,6]pyrano[2,3-d]pyrimidine-5,7(1H,6H)-dione (MNDPPD) were evaluated using the theoretical and experimental methods. Then, the molecular structure of this drug optimized using the Gaussian 09 software with Hartree-Fock (HF) and density functional theory (DFT)methods with 6–311+G(d,2p) basis set. The 1H and 13C NMR spectra were computed using the gauge-invariant atomic orbital (GIAO) method, showing a good agreement with the experimental ones. The calculated vibrational frequencies and chemical shift values were compared using the FT-IR and NMR analysis. The last one UV–vis absorption spectra were analyzed at the presence of five solvent (H2O, DMSO, CH3CN, CH3NO2 and CH3CHCl2), saved at the range of 200–550 nm. The hyper-conjugative interaction energy and electron densities of donor and acceptor bonds were calculated using the natural bond orbital (NBO) analysis. In addition, frontier molecular orbitals analysis, non-linear optical (NLO)activity, electro negativity, ionization energy, global hardness, global softness, andthe energy gap between the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) were calculated. The results showed that the experimental and computational data are consistent with each other.

In this research study, a green synthetic route for eco-safe and solvent-free preparation of 12-aryl-tetrahydrobenzo[α]xanthene-11-ones, 1,8-dioxo-octahydroxanthenes and 14-aryl-14H-dibenzo[α,j]xanthenes using formic acid as a bio-based, natural and versatile catalyst was developed. The notable advantages of this green approach are use of bio-based, natural, easy-to-handle and available readily green catalyst, absence of hazardous organic solvents, solvent-free conditions with good to high yields and short reaction times and one-pot reactions. Furthermore, one of the source of environmental pollutions is the usage of organic solvents under reflux conditions and the need for column chromatography to purity the products. In this present work, the products were obtained through simple filter with no need column chromatographic separation.

In this work, the newly prepared functionalized graphene oxide (GO), denoted as GO-SiC3-NH3-H2PW, was found as an effective nanocatalyst for a one-pot reaction of dimedone, aryl aldehydes, and malononitrile, giving rise to tetrahydrobenzo[b]pyran derivatives. The reactions were conducted in water, giving the corresponding products in 88-98% yields over 4-15 min. Other advantages of the method include cheap catalyst, easy work-up, absence of any dangerous solvents and the catalyst's reusability for up to five consecutive runs (97, 96, 95, 95, and 94 in first to fifth use, respectively).