European Journal of Chemistry

N'-Acetyl-N'-phenyl-2-naphthohydrazide, a biologically relevant organic molecule, was synthesized following a reported method and characterized based on its single X-ray crystallographic studies. The present manuscript deals with its detailed molecular interactions and X-ray crystal structure. Its space group is P-1 with the following unit cell parameters: a = 8.9164(7), b = 9.7058(9), c = 17.7384(12) Å, α = 88.308(7)°, β = 89.744(6)°, γ = 86.744(7)° and Z = 2. Crystal structure was solved by direct method and refined by full matrix least squares procedure to a final R value of 0.0580 and to a GOOF value of 1.066. The X-ray diffraction analyses showed that the asymmetric unit contains two crystallographically independent molecules. The crystal structure is stabilized by elaborate network of N-H···O and C-H···O hydrogen bonds along with C-H···π and π···π interactions to form supramolecular structures.

Treatment of the contaminated aqueous solutions to improve their quality is indispensible for their reuse resulting in an emergent challenge to develop facile, nontoxic and less energy consuming techniques to purify water. Present study is therefore aimed at the synthesis of an adsorbent using agricultural waste i.e. coconut shell. The charcoal obtained from coconut shell was modified by acid activation and manganese doping following a simple chemical route. The products were characterized by scanning electron microscopy, energy dispersive X-ray analysis and infrared spectroscopy. Preliminary studies were carried out to compare the adsorption potential of acid modified coconut shell charcoal (AMCSC) and manganese doped coconut shell charcoal (MDCSC) for the removal of chromium (VI) and iron (III) from aqueous solutions. Various physicochemical parameters such as adsorbent dosage, initial metal ions concentration and pH were studied. MDCSC was found to be a better adsorbent for metals as compared to AMCSC and removed chromium more efficiently than iron from synthetic solutions i.e. 56.10% at optimum conditions i.e. 0.6 g/L adsorbent dosage, 10 mg/L initial metal ions concentration and pH = 3. The effect of adsorbents on color and conductivity of the aqueous solutions was also noted; slight variation in color of all the aqueous solutions with a maximum of 91.67% removal was observed.

Specific, and precise spectrophotometric methods are developed and validated for the simultaneous determination of the binary antihypertensive mixture nebivolol hydrochloride and valsartan in the zero-order spectrum. The methods applied for the determination of this antihypertensive mixture are constant center spectrophotometric resolution technique, constant center spectrum subtraction resolution technique, and advanced concentration value. Nebivolol hydrochloride was determined by its zero order spectra at 280 and 213 nm while for valsartan it determined by its zero order spectra at 250 nm. All developed methods were applied for the determination of the cited drugs in the pharmaceutical formulation and the results obtained were statistically compared with each other and with those of the reported method. The comparison showed that there is no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

The extraction behaviour of zirconium(IV) from sulfuric acid medium has been studied with a binary mixture of tri-n-octyl amine (TOA) and Cyanex923 (a mixture of four trialkyl phosphine oxides) in kerosene using a novel liquid-liquid extraction method. Quantitative extraction of zirconium(IV) with binary mixture of Cyanex923 and TOA in kerosene was studied by changing different parameters such as acid variation, extractant variation, effect of chloride ion concentration, effect of temperature, metal concentration variation, diluent effect, and pH effect. The percentage of extraction of zirconium(IV) decreased when the concentration of Cyanex923 and TOA increased. The percentage of zirconium(IV) was observed as  97.56% in a binary mixture of 0.007 M Cyanex923 and 0.06 M TOA. Kerosene was found to be an effective diluent for the extraction of zirconium(IV) with 97.56% extraction using a binary mixture of Cyanex923 and TOA. In addition, the stripping of the zirconium(IV) metal ion in the organic phase was also examined.

A simple solvent extraction method was used to analyze alcohol-based hand rubs (ABHRs) using gas chromatography with a flame ionization detector. 79 samples including 68 liquid and 11-gelled ABHRs were analyzed in the Food and Drug Laboratories Research Center of Mashhad, Iran. 17 samples had methanol, 50 samples had the correct percentage of alcohol (60-80%), and 12 samples had the incorrect percentage of alcohol (<60%). The RSD% of methanol, ethanol, and isopropanol were as 2.28, 2.18, and 1.52, respectively. The relative recoveries for methanol, ethanol, and isopropanol were 102.5, 97.8, and 114, respectively. All experiments were repeated three times. The limit of detection and the limit of quantification for methanol, ethanol, and isopropanol were obtained as 0.22, 0.24, 0.10 (%) and 0.71, 0.82, 0.68 (%), respectively.

The groundwater is one of the biggest natural resources for providing drinking water to millions of people all around the globe. However, the presence of large amount of arsenic(V) in water causes serious health hazards to the consumers which necessitates the development of cost-effective remediation. The CuO/TiO₂ nanocomposites were prepared by the precipitation-deposition method for the removal of the arsenate ion (AsO₄^3-) from water. The prepared samples were characterized by powder X-ray diffraction, Fourier transform infrared, and scanning electron microscopy to examine crystallite size and structure, material purity, textural features, morphology, and surface area. The effect of different operating parameters such as pH, contact time, initial concentration of arsenic(V) and nanocomposite dose on the removal rate of arsenic(V) was examined to optimize the adsorption performance of the CuO/TiO₂ nanocomposite. In addition, the adsorption mechanism was studied by employing Langmuir and Freundlich adsorption isotherms to gain better understanding of the adsorption mechanism. The Freundlich adsorption isotherm fits well with the experimental data and the maximum adsorption capacity of the Langmuir model was found to be 90 mg/g for arsenic(V). The CuO/TiO₂ nanocomposite shows remarkable adsorption performance for the treatment of arsenic(V) contaminated water samples. This study provides a cost-effective solution for the safe use of groundwater contaminated with arsenic.

Tetrahydrocarbazoles are important class of heterocycles that exhibit numerous biological properties. They are also found in several natural products. In the present study, Fischer indolization of L-menthone was investigated for diastereoselectivity using different reaction conditions. No appreciable diastereoselectivity was observed for the acids used except CuBr and boric acid at varying temperatures, where satisfactory results were obtained. In addition, a small library of new (2R,4aS)-2,3,4,4a-tetrahydro-1H-carbazole analogs was reported and structurally characterized using spectroscopic techniques herein. Additionally, the compounds were evaluated against different biological activities, such as carbonic anhydrase inhibitory, immunomodulatory, and anticancer activities and did not show any activity. As the synthesized library was found safe when tested against cytotoxicity in normal cell line, it will be explored for other biological activities in near future to identify its biological outcome.

Ni(II), Cu(II), and Zn(II) complexes of the tridentate heterocyclic ligand, 2-(phenyl(pyridin-2-yl)methylene)hydrazine-1-carbothioamide (HL) have been synthesized and characterized by various spectroscopic techniques and elemental analyses. Infrared spectroscopy shows that the ligand coordinates to the metal ions through the azomethine and pyridine nitrogen atoms as well as the sulfur atom of the thioamide group to form a tridentate chelate system. In vitro screening of metal complexes against four bacterial strains (Staphylococcus aureus (ATCC 43300), Klebsiella pneumoniae (ATCC 700603), Methicillin resistant staphylococcus aureus (ATCC 33591), Shigella flexneri (NR 518)) and four fungal strains (Candida albicans (NR 29444), Candida albicans (NR 29445), Candida albicans (NR 29451), Candida krusei (HM 1122)) indicate that the Cu(II) complex showed good antibacterial activity on Methicillin resistant staphylococcus aureus (ATCC 33591) while the Zn(II) complex showed moderate activity against some of the bacterial and fungi strains. Antioxidant studies reveal that the complexes are more potent than the ligand to eliminate free radicals, with the Ni(II) complex showing the best free radical scavenger.

Inducible nitric oxide synthase (iNOS) plays an important role in the inflammatory processes via accelerating the production of nitric oxide (NO). The efforts to develop small molecules as selective inhibitors of iNOS are being reported across the globe. The current study explores varied benzimidazole-coumarin derivatives as anti-iNOS agents. Literature survey suggests 2-aminobenzimidazole, coumarin nucleus, and 4-atom linker as important structural components for iNOS inhibition. Target compounds were designed and synthesized by coupling 2-aminobenzimidazole with (un)substituted coumarin through different linkers. These were docked in iNOS (1QW4) and nNOS (1QW6) targets to ascertain their iNOS selectivity, and evaluated for NO and iNOS inhibitory activities in vitro. The most active inhibitors were subsequently evaluated for acute toxicity and anti-inflammatory activity using carrageenan-induced rat paw edema model in vivo. All compounds possessed moderate to good NO and iNOS inhibitory activities. Compounds 14a, 14b, 14d, and 14e were the most potent inhibitors in vitro. These were found to significantly reduce the inflammation. Compounds 14d and 14e have been identified as the most potent iNOS inhibitors to combat inflammation. These derivatives may serve as potential compounds as such against iNOS, or as leads for the development of novel anti-iNOS agents.

In-silico quantitative structure-activity relationship (QSAR) study was performed to develop a model on a series of novel pyrazole derivatives containing acetamide moiety which exhibited considerable antiproliferative activity against human colorectal adenocarcinoma cell line HT-29. The model obtained has a correlation coefficient (r) of 0.9693, squared correlation coefficient (r²) of 0.9395 and a leave-one-out (LOO) cross-validation coefficient (Q²) value of 0.8744. The predictive power of the developed model was confirmed by the external validation which has an r² value of 0.9488. These parameters confirm the stability and robustness of the model to predict the activity of a new designed set of 3,5-dimethyl-pyrazole derivatives (22-36), results indicated that the compounds 26, 31, 35, and 36 showed the strongest antiproliferative activity with (IC₅₀ = 0.182, 0.172, 0.166 and 0.024 μM, respectively) against human colorectal adenocarcinoma cell line HT-29 compared to the reference vemurafenib with (IC₅₀ = 1.52 μM). Molecular docking was performed on the new designed compounds with the human colorectal adenocarcinoma cell line 5JRQ protein. The docking results showed that compounds 26, 31, 35, and 36 have docking affinity of -8.528, -5.932, 23.017 and 18.432 kcal/mol, respectively.

The study seeks to determine the most significant factors affecting arsenic and chromium enrichment using novel P-ZrO₂CeO₂ZnO nanoparticles/alginate beads in order to minimize the total number of runs needed to successfully run the experiment. The effects of interactions between factors were also evaluated so that the optimum conditions which are not affected by the other factors are chosen for the experiments. The most significant factors on arsenic and chromium enrichment were screened for by using a half-factorial design, followed by the optimization of significant factors using the full-factorial design, and the interaction between factors was determined using ANOVA and interaction plots. The most significant factors for chromium recovery were sample volume, eluent flow rate, and sorbent dosage. For both chromium and arsenic recovery, interactions occurred between sample volume, dosage, and pH. The optimum conditions chosen for the experiment that gave favourable results for both metal ions were sample volume 5 mL, dosage 40 mg, pH = 7 and eluent flow rate 1 mL/min. This study showed that a preliminary screening step for the most significant factors for arsenic and chromium enrichment helps to reduce the number of total runs, and for the same experiment interactions between factors were present; hence, it is necessary to take this into account during the experimental design.

A detailed study of the electronic band structures and partial density of states of Bi₅O₇NO₃ with different exchange correlation functionals was performed using the generalized gradient approximation. Bi₅O₇NO₃ has two direct energy gap transitions of 2.84 and 3.66 eV at the experimental lattice parameters, revealing a semiconductor characteristic of a crystal. Molecular Mechanics; however, tends to underestimate the band-gap energies with indirect characters. This deviation is due to the slight decrease in the cell edges and the significant increase in the β angle during the optimization process. The mechanism of removal of methyl orange and its derivatives by the Bi₅O₇NO₃ unit cell, which has the same experimental UV-Vis band gap, was later investigated through a DMol3 module. To do that, frontier molecular orbitals, global reactivity parameters, and electrostatic potential surface maps were evaluated. The high values of the electrophilicity indexes hint that the dyes are more reactive and can work as good electrophile species. A molecular packing of dye molecules and the ionic natural of Bi₅O₇NO₃ generate a synergistic effect between π-π stacking, anion-π stacking, cation-π stacking and electrostatic interactions, which are thought to be the driven forces during dye removal.

A new hydrazide functionalized Schiff’s base derivative, N'-(3,4-dichlorobenzylidene)-4-hydroxybenzohydrazide (I), has been synthesized using a solvent-assisted mechano-chemical grinding strategy and structurally characterized using elemental analysis, ¹H NMR and crystallographic studies. The single crystal X-ray diffraction study depicts that molecule is puckered with two aromatic rings lying out-of-plane in near anti-configuration across the C=N bond. The weak interactions involved in supramolecular framework formation are Cl···O, Cl···Cl, Cl···H, Cl···N, C···H, and O···H contacts. The intermolecular O···H interaction being stronger than other dispersive interactions such as halogen bonding, interlocks the molecules in a 2D sheet-type packing. All the structure directing interactions involved in developing crystal architecture are addressed with Hirshfeld surface analysis and fingerprint plots. The energy framework analysis shows visualization of 3D topology of short contacts related to molecular packing of compound I which further clarifies the predominance of both Coulombic and dispersive energies in developing supramolecular architecture.

Graphene is showing its versatility continuously by playing the most important role in many fields of science. Water treatment is one of them. In the present scenario, the supply of the safe and pure water has become the main priority. Especially, the most denser and populated areas are demanding of it. Although water treatment is done by applying different methods using different materials, no material showed the results as good as graphene-based materials. The current article deliberates not only the main properties of graphene but also their importance in the treatment of water. Besides, the current review also pronounces the method of graphene separation from the water after use and recycling.  Efforts are made to discuss the role of graphene materials in the treatment of water. Henceforward, this article will definitely be very helpful for researchers, academicians, and administration authorities who are planning and developing new strategies for the removal of ionic as well as organic impurities from water.

Erratum to “Synthesis, characterization and crystal structure of platinum(II) complexes with thiourea derivative ligands” [Eur. J. Chem. 9 (4) (2018) 360-368].