Photochromism of dihydroindolizines. Part XVIII: palladium-catalyzed Negishi coupling for the synthesis of photochromic dihydro 5-azaindolizine-linker-conjugates with a terminal ethylene anchoring group

Eight new photochromic dihydro 5-azaindolizine-linker-conjugates with a terminal ethylene anchoring group have been synthesized via palladium-catalyzed Negishi coupling. Polychromatic light irradiation of the photochromic dihydro 5-azaindolizines (DHAIs) led to ring-opened colored betaines which underwent reversible thermal 1,5-electrocyclization into their corresponding DHAIs in the second domain. The noteworthy multiaddressable photochromic properties are useful for a plethora of new applications for these materials such as anchoring the ethylene group to metal-oxide nanoparticles.     

Synthesis and Assessment of Two Malonyl Dihydrazide Derivatives as Corrosion Inhibitors for Carbon Steel in Acidic Media: Experimental and Theoretical Studies

Despite the extensive use of carbon steel in all industrial sectors, particularly in the petroleum industry, its low corrosion resistance is an ongoing problem for these industries. In the current work, two malonyl dihydrazide derivatives, namely 2,2’-malonylbis (N-phenylhydrazine-1-carbothiamide (MBC) and N’1, N’3-bis(-2-hydroxybenzylidene) malonohydrazide (HBM), were examined as inhibitors for the carbon steel corrosion in 1.0 M HCl. Both MBC and HBM were characterised using thin-layer chromatography, elemental analysis, infrared spectroscopy, and nuclear magnetic resonance techniques. The corrosion tests were performed using mass loss measurements, polarisation curves, and electrochemical impedance spectroscopy. It is obtained from the mass loss studies that the optimal concentration for both inhibitors is 2.0 × 10⁻⁵ mol/L, and the inhibition efficiencies reached up to 90.7% and 84.5% for MBC and HBM, respectively. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) indicate an increased impedance in the presence of both MBC and HBM and mixed-type inhibitors, respectively. Both inhibitors can mitigate corrosion in the range of 298–328 K. Values of free energy changes obtained from the Langmuir model suggest that the inhibitors suppress the corrosion process principally by chemisorption. The computational investigations were conducted to identify the factors connected with the anti-corrosive properties of the examined inhibitors.     

New Composite Sorbent for Removal of Sulfate Ions from Simulated and Real Groundwater in the Batch and Continuous Tests

The evaluation of groundwater quality in the Dammam formation, Faddak farm, Karbala Governorate, Iraq proved that the sulfate (SO₄²⁻) concentrations have high values; so, this water is not suitable for livestock, poultry and irrigation purposes. For reclamation of this water, manufacturing of new sorbent for permeable reactive barrier was required through precipitation of Mg and Fe hydroxides nanoparticles on the activated carbon (AC) surface with best Mg/Fe molar ratio of 7.5/2.5. Mixture of 50% coated AC and 50% scrap iron was applied to eliminate SO₄²⁻ from contaminated water with efficiency of 59% and maximum capacity of adsorption equals to 9.5 mg/g for a time period of 1 h, sorbent dosage 40 g/L, and initial pH = 5 at 50 mg/L initial SO₄²⁻ concentration and 200 rpm shaking speed. Characterization analyses certified that the plantation of Mg and Fe nanoparticles onto AC was achieved. Continuous tests showed that the longevity of composite sorbent is increased with thicker bed and lower influent concentration and flow rate. Computer solution (COMSOL) software was well simulated for continuous measurements. The reclamation of real contaminated groundwater was achieved in column set-up with efficiency of 70% when flow rate was 5 mL/min, bed depth was 50 cm and inlet SO₄²⁻ concentration was 2301 mg/L.     

Protective Effects of Thymoquinone,an Active Compound of Nigella sativa,on Rats with Benzo(a)pyrene-Induced Lung Injury through Regulation of Oxidative Stress and Inflammation

Benzopyrene [B(a)P] is a well-recognized environmental carcinogen, which promotes oxidative stress, inflammation, and other metabolic complications. In the current study, the therapeutic effects of thymoquinone (TQ) against B(a)P-induced lung injury in experimental rats were examined. B(a)P used at 50 mg/kg b.w. induced lung injury that was investigated via the evaluation of lipid profile, inflammatory markers, nitric oxide (NO), and malondialdehyde (MDA) levels. B(a)P also led to a decrease in superoxide dismutase (SOD) (34.3 vs. 58.5 U/mg protein), glutathione peroxidase (GPx) (42.4 vs. 72.8 U/mg protein), catalase (CAT) (21.2 vs. 30.5 U/mg protein), and total antioxidant capacity compared to normal animals. Treatment with TQ, used at 50 mg/kg b.w., led to a significant reduction in triglycerides (TG) (196.2 vs. 233.7 mg/dL), total cholesterol (TC) (107.2 vs. 129.3 mg/dL), and inflammatory markers and increased the antioxidant enzyme level in comparison with the group that was administered B(a)P only (p < 0.05). B(a)P administration led to the thickening of lung epithelium, increased inflammatory cell infiltration, damaged lung tissue architecture, and led to accumulation of collagen fibres as studied through haematoxylin and eosin (H&E), Sirius red, and Masson’s trichrome staining. Moreover, the recognition of apoptotic nuclei and expression pattern of NF-κB were evaluated through the TUNEL assay and immunohistochemistry, respectively. The histopathological changes were found to be considerably low in the TQ-treated animal group. The TUNEL-positive cells increased significantly in the B(a)P-induced group, whereas the TQ-treated group showed a decreased apoptosis rate. Significantly high cytoplasmic expression of NF-κB in the B(a)P-induced group was seen, and this expression was prominently reduced in the TQ-treated group. Our results suggest that TQ can be used in the protection against benzopyrene-caused lung injury.     

Progress in the Understanding of the Key Pharmacophoric Features of the Antimalarial Drug Dihydroartemisinin: An Experimental and Theoretical Charge Density Study

The accurate, experimental charge density distribution, ρ( r ), of the potent antimalarial drug dihydroartemisinin (DHA) has been derived for the first time from single‐crystal X‐ray diffraction data at T=100(2) K. Gas‐phase and solid‐state DFT simulations have also been performed to provide a firm basis of comparison with experimental results. The quantum theory of atoms in molecules (QTAIM) has been employed to analyse the ρ( r ) scalar field, with the aim of classifying and quantifying the key real‐space elements responsible for the known pharmacophoric features of DHA. From the conformational perspective, the bicyclo[3.2.2]nonane system fixes the three‐dimensional arrangement of the 1,2,4‐trioxane bearing the active O? O redox centre. This is the most nucleophilic function in DHA and acts as an important CH???O acceptor. On the contrary, the rest of the molecular backbone is almost neutral, in accordance with the lipophilic character of the compound. Another remarkable feature is the C? O bond length alternation along the O‐C‐O‐C polyether chain, due to correlations between pairs of adjacent C? O bonds. These bonding features have been related with possible reactivity routes of the α‐ and β‐DHA epimers, namely 1) the base‐catalysed hemiacetal breakdown and 2) the peroxide reduction. As a general conclusion, the base‐driven proton transfer has significant non‐local effects on the whole polyether chain, whereas DHA reduction is thermodynamically favourable and invariably leads to a significant weakening (or even breaking) of the O? O bond. The influence of the hemiacetal stereochemistry on the electronic properties of the system has also been considered. Such findings are discussed in the context of the known chemical reactivity of this class of important antimalarial drugs.     

Spectrofluorometric determination of certain quinolone antibacterials using metal chelation

Simple, rapid, reliable, and sensitive spectrofluorometric methods were developed for the determination of eight quinolone antibacterials namely ciprofloxacin, norfloxacin, lomefloxacin, difloxacin, amifloxacin, pefloxacin, ofloxacin, and nalidixic acid. The methods depend on the chelation of each of the studied drugs with zirconium, molybdenum, vanadium or tungsten to produce fluorescent chelates. Different factors affecting the relative fluorescence intensity of the resulting chelates were studied and optimised. At the optimum reaction conditions, the drug-metal chelates showed excitation maxima ranging from 274 to 295 nm and emission maxima ranging from 409 to 495 nm. The chelates were found to be stable at room temperature for 2 days and show good stability upon increasing temperature to 50 °C for about 1 h. Rectilinear calibration graphs were obtained in the range of 10-60 ng ml⁻¹ for each of the investigated drugs and the limits of detection and quantitation ranged from 1.214 to 2.046 and from 4.047 to 6.819 ng ml⁻¹, respectively. The molar ratios of the formed chelates were determined by Job's method and their association constants were also calculated. The developed methods were applied successfully for the determination of the studied drugs in their pharmaceutical dosage forms with a good precision and accuracy compared to official and reported methods as revealed by t- and F-tests. They were also applied for the determination of studied drugs in spiked urine and plasma samples.     

聚酚藏花红功能碳纳米管生物阳极制备及其在乙醇传感器应用

应用电化学法聚合酚藏花红（PPS）功能化的单壁碳纳米管,以其作为烟酰胺辅酶（NADH）氧化的电化学催化剂（电极）,构建基于乙醇脱氢酶的安培型乙醇生物电化学传感器.该电极于0.0 V时,对NADH具有很好的催化性能.而单体酚藏花红则由于其电位过低（-0.48 V）,不能显示催化性能.循环伏安和计时安培法测试表明：该传感器...     

SSZ-53 and SSZ-59: two novel extra-large pore zeolites

The syntheses, structure solutions, and physicochemical and catalytic characterizations of the novel zeolites SSZ-53 and SSZ-59 are described. SSZ-53 and SSZ-59 were synthesized under hydrothermal conditions with the [1-(4-fluorophenyl)cyclopentylmethyl]trimethyl ammonium cation and 1-[1-(4-chlorophenyl)cyclopentylmethyl]-1-methyl azocanium cation, respectively, as structure-directing agents. The framework topology of SSZ-53 was solved with the FOCUS method, and the structure of SSZ-59 was determined by model building. Rietveld refinement of synchrotron X-ray powder diffraction data confirms each proposed model. SSZ-53 and SSZ-59 each possess a one-dimensional channel system delimited by 14-membered rings. Results from transmission electron microscopy, electron diffraction, catalytic experiments (spaciousness index and constraint index tests), and argon and hydrocarbon adsorption experiments are consistent with the proposed structures.     

Multicomponent access to novel proline/cyclized cysteine tethered monastrol conjugates as potential anticancer agents

The versatility of multicomponent Biginelli’s reaction is exploited in the development of proline and cyclized cysteine tethered conjugates of monastrol, a kinesin Eg5 inhibitor. Ten new conjugates are synthesized focusing on structural replacement of the ester moiety (C-5 position) of the monastrol backbone with amino acid based amide moieties. On cytotoxic evaluation, conjugate 24 has shown promising in vitro cytotoxic activity against leukemia. Molecular docking studies revealed that the conjugates 19 and 24 exhibit better interaction at kinesin Eg5 receptor compared to monastrol. Moreover, computational calculations and predictions of important molecular properties suggest that these new amino acid based conjugates could be further improved to provide potential anticancer agents.