Solid Complexes Research Articles

A quantitative recovery process of rare earth in bastnaesite leachate for energy saving and emission reduction

Extraction-precipitation method is a novel separation strategy, a new extraction-precipitant N-lauroyl sarcosine (NLSA) is synthesized in this article. It was found that the extraction-precipitant has a task-specific precipitation ability for rare earth (RE). RE(III) can be recovered quantitatively in the presence of Ca(II), Mg(II), Al(III). When the precipitation rate of RE is 96 %, the precipitation rate of Al is only 6.8 %. The separation coefficient (βRE/Al) reaches 375, and the precipitation of Ca(II) and Mg(II) is negligible. The solid complex produced in the precipitation process has a large particle size which is easy to be separated. In addition, the precipitation can be completely stripped with 6 mol/L hydrochloric acid, and the REO concentration of stripping solution reaches 255 g/L. After 5 cycles of extraction-precipitation, the specific precipitation of NLSA on RE remains basically unchanged. Mechanism analyses indicate that the extraction-precipitation process is cation exchange. The specificity of the precipitation process can be attributed to the steric hindrance of amide bonds hindering the coordination of Al (III). Finally, a novel enrichment process of bastnaesite leachate is developed to enrich RE, which can effectively remove impurities, so as to effectively avoid the generation of impurity removal residue. Also the enrichment process can reduce energy consumption and carbon emission. The pulverized coal consumption in this process is only 6.25 % of the existing industrial process, and the carbon emission has been decreased by 93.75 %.

DMAP and HMTA manganese(III) meso-tetraphenylporphyrin-based coordination complexes: Syntheses, physicochemical properties, structural and biological activities

The reactions of the (triflato)(meso-tetra(para-methoxyphenyl)porphyrinato)manganese(III) ([MnIII(TMPP)(SO3CF3)] complex with an excess of 4-dimethylaminopyridine (DMAP) and hexamethylenetetramine (HMTA) have been examined. These reactions yield crystalline [MnIII(TMPP)(DMAP)2](0.1Cl)(0.9SO3CF3)•2CHCl3 (I) and [MnIII(TMPP)(HMTA)2](SO3CF3)•2CH2Cl2 (II) complexes, respectively. The hyper d-type electronic spectra of I-II are characteristic for high-spin (S = 2) Mn(III) metalloporphyrins with very redshifted Soret bands. A cyclic voltammetry investigation was carried out on these two Mn(III) coordination compounds. The crystal structures of the solid complexes I-II were determined by X-ray single-crystal diffraction and elucidated by Hirshfeld surface approach. Furthermore, bioactivity of the H2TMPP free base, the [MnIII(TMPP)(SO3CF3)] starting material and complexes I-II, was assessed by a set of in vitro tests checking for antioxidant, antibacterial and antifungal (against several strains) effects.

Novel Complexes of 3-[3-(1H-Imidazol-1-yl)propyl]-3,7-diaza-bispidines and β-Cyclodextrin as Coatings to Protect and Stimulate Sprouting Wheat Seeds.

We report the syntheses and characterization of novel 3,7-bicycl[3.3.1]bispidines possessing an imidazolpropyl group attached to N-3, and at N-7 a Boc group, as well as a benzoylated-oximated group at C-9. These compounds were complexed with β-cyclodextrin [β-CD] and evaluated as seed protectors of selected wheat seedlings. Using strong acid, condensations of N-substituted piperidones with the appropriate imidazolpropyl groups at N-3 and N-7 led to bispidinones 6 and 7. These intermediates were reduced to the corresponding 3,7-diazabicyclo[3.3.1]nonane targets. The oxime at C-9 was benzoylated to yield 13. Heating these 3,7-diazabicyclo[3.3.1]nonanes in ethanol with β-CD generated the complexes required. We investigated the ability of such complexes as coatings on seedlings to protect and stimulate growth of three varieties of wheat, namely Kazakhstanskaya-10, Severyanka, and Miras. The complex of 3-[3-(1H-imidazol-1-yl)propyl]-7-(3-methoxypropyl)-3,7-diazabicyclo[3.3.1]nonane (2) promoted growth in the root systems of all three wheat varieties by more than 30% in Kazakhstanskaya-10, 30% in Severyanka and 8.5% in Miras. A complex of 3-Boc-7-[3-(1H-imidazol-1-yl)propyl]-3,7-diazabicyclo[3.3.1]nonane (9) increased both shoot and root length in only the Severyanka variety. The complex of 3-(3-butoxypropyl)-7-[3-(1H-imidazol-1-yl)propyl]-3,7-diazabicyclo[3.3.1]nonane (11) stimulated both shoot growth (0.8%, 12.3%, 13.5%) and root growth (12.3%, 9.4%, 21.7%) in all three varieties of wheat, respectively. The nature of substituents on the bispidine affect the activity. Solid complexes (1:1) were generated as powders which melted above 240 °C (dec) and were characterized via elemental analyses as 1:1 complexes.

SYNTHESIS AND BIOLOGICAL ACTIVITY OF 3d-­METAL COMPLEXES WITH BIS(PHOSPHONOMETHYL)AMINOSUNRIC ACID

New complexes of 3d-metals (Co2+, Ni2+, Zn2+) with bis(phosphonomethyl)aminosuccinic acid (H6BPMAS) have been synthesized. The complexes were studied in aqueous solutions at ratios M2+:H6BPMAS = 1:1 in a wide pH range (1÷10). Regardless of the nature of the metal, the formation of complexes of the general composition [M(HnBPMAS)(OH)m] (n= 4÷0, m=1÷0) is shown. The stability constants of the formed differently protonated complexes are calculated and diagrams of their distribution are plotted. It is shown that the process of complexation takes place most completely in the region of pH>4. For all bis(phosphonomethyl)aminosuccinates of 3d metals, the dominance of the complex with one form of the ligand occurs in approximately the same pH ranges. A close order of change in the values of lgKst. complexes testifies to the same type of structure of their internal coordination sphere.
 Solid complexes of the composition Na4[MBPMAS]⋅4H2O were synthesized. Their composition, structure, and thermal characteristics were determined by the set of me­thods such as diffuse reflectance spectroscopy, IR spectroscopy, DTA and non-quantitative mass spectrometry. It is proved that the complexes have the structure of a distorted octahedron, in which the 3-d metal ions are bound to the oxygen atoms of the carboxyl and phosphonic groups and the tertiary nitrogen atom of the ligand. At the same time, two 5-membered (aminomethylenephosphonic and glycine) and one 6-membered (β-alanine) metallocycles are formed in bis(phosphonomethyl)aminosuccinates.
 The biological activity of H6BPMAS and its complexes with Ni(II) and Co(II) against non-pathogenic bacterial species of microorganisms Pseudomonas fluorescens and Pseudomonas aureofaciens was studied. The study of the activity of substances was carried out in a liquid sterile Hiss medium. The maxi­mum stimulating effect on the growth of bacterial cultures for the studied compounds was recorded at a concentration of 1 µM in 24 hours after the start of cultivation of mic­ro­organisms. The highest growth of microorganisms was recorded for metal complexes (50% Na4[CoBPMAS]·4H2O and 35% Na4[NiBPMAS]·4H2O). The maximum stimulating effect on the growth of bacterial cultures is shown by the Co(II) complex, which is able to initiate the synthesis of one of the most important growth hormones - heteroauxin.

Preparation and chemical study on metallic bonding with antibiotics in nanometer form to raise the therapeutic efficiency: structural characterizations of Cu(II), Co(II) and Ni(II) 6-aminopenicillinic acid complexes


 ABSTRACT. The medical and pharmaceutical areas are interested in the production of metal-biomolecule complexes because to their strong biological activity against bacteria, fungus, and cancers. The purpose of this paper was to synthesise of three coloured transition metal complexes of copper(II), cobalt(II), and nickel(II) with a 6-aminopenicillinic drug ligand (6-apen). The analyses of elemental analysis (carbon, hydrogen, and nitrogen), molar conductivity, magnetic susceptibility, infrared (FTIR), and electronic (UV-Vis) spectroscopy provided a thorough characterization of the solid complexes. The low molar conductance values of the produced solid complexes suggested that they were not electrolytic. The 6-apen drug ligand has more than one site of coordination as carboxylic group, β-lactam nitrogen, nitrogen of –NH2 group, oxygen of carbonyl β-lactam group and sulfur of the five–member ring. The microanalytical, spectroscopic and thermogravimetric analyses indicated a 1:2 (Metal : Ligand) stoichiometry of all complexes. The 6-apen ligand acts as a bidentate ligand that the coordination site occurs through the oxygen of deprotonated carboxylic group and β-lactam nitrogen. The thermogravimetric analysis confirmed the absence of crystalline water molecules outside the coordination sphere. The anticancer availability of the 6-apen free drug was checked against of 2Q7K receptor prostate cancer using a molecular docking calculation.
 
 KEY WORDS: 6-Aminopenicillinic, Coordination, Metals ions, FTIR, Molecular docking
 Bull. Chem. Soc. Ethiop. 2023, 37(1), 91-100. 
 DOI: https://dx.doi.org/10.4314/bcse.v37i1.8

Study on characteristics of oil and gas occurrence and reservoir space of medium-high maturity continental shale—A case study of middle jurassic lianggaoshan formation in fuling block, southeast of sichuan basin, south China

Possessed of easy access to development and fair economic benefits, medium-high maturity continental shale oil and gas have become the focus of shale oil and gas study in the future. Shale oil and gas mainly occur in pores, but studies on the pore characteristics of shale oil and gas occurrence are by no means sufficient. Focused on shale from the Middle Jurassic Lianggaoshan Formation in Well TYX, Fuling block, southeast of Sichuan Basin where a breakthrough in shale oil and gas exploration was recently achieved, this study selects core samples and conducts a series of analyses, including vitrinite reflectance analysis, kerogen microscopic examination experiment, total organic carbon (TOC) content analysis, mineral composition analysis, gas content measurement, isothermal adsorption experiment, S1 content analysis, and others. The analyses are to identify the pore characteristics of the continental medium and high maturity shale oil and gas by virtue of scanning electron microscope (SEM) with Ar-ion milling and the image processing software ImageJ. The conclusions are drawn as follows: in terms of lithofacies, medium-high maturity continental shale oil and gas mainly occur in organic-rich clay shale and organic-rich mixed shale; with regard to material composition, shale oil and gas mainly occur in organic matter, illite-smectite mixed layers and illite. Shale adsorbed gas content accounts for at most 40% of the total shale gas content and shale free gas content takes up at least 60% of the total shale gas content. Pores of solid bitumen, solid bitumen-clay mineral complex mass, clay minerals, structured vitrinite, and funginite are mostly developed in shale. Among them, the first three types of pores are the main reservoir space in shale considering their large number, good roundness, medium pore diameter, fairly good roundness of pore edges, and the complex shapes which altogether contribute to the large surface porosity.

Study of Thermodynamic Parameters for Nano Zinc Sulfate in the Presence of Proline (amino acid) in Mixed MeOH-H2O Solvents at Different Temperatures

A set of conductometric measurements were conducted using zinc sulfate (ZnSO4) with different percentages of methanol (MeOH) and water in the presence of Proline (ligand) at four temperatures. The present work aims to estimate diverse thermodynamic parameters for nano Zn (II) sulfate alone and with amino acid (H2Prol) to form complexes in the solutions. All the data for the used electrolytes and ions is very important for analyzing the salt and explaining the different ion-ion and ion-solvent interactions. The isolated metal complexes derived from the interaction of amino acids with Zn (II) are characterized by chemical and physical methods. Based on spectral data (IR, and UV-Vis), a structure for separated solid complexes is presented and magnetic studies. Furthermore, biological activity measurements are executed, which benefits in determining the factors impacting the thermodynamic parameters and physical properties of the formed complexes in the solution.

SARS-CoV-2 main protease (3CLpro) interaction with acyclovir antiviral drug/methyl-β-cyclodextrin complex: Physiochemical characterization and molecular docking

During the current outbreak of the novel coronavirus disease 2019 (COVID-19), researchers have examined several antiviral drugs with the potential to inhibit the proliferation of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The antiviral drug acyclovir (AVR), which is used to treat COVID-19, in complex with methyl-β-cyclodextrin (Mβ-CD) was examined in the solution and solid phases. UV–visible and fluorescence spectroscopic analyses confirmed that the guest (AVR) was included inside the host (Mβ-CD) cavity. A solid inclusion complex of AVR was prepared by co-precipitation, physical mixing, kneading, and bath sonication methods at a 1:1 ratio of Mβ-CD:AVR. The prepared Mβ-CD:AVR inclusion complex was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) analysis. Phase solubility studies indicated the Mβ-CD:AVR inclusion complex exhibited a higher stability constant and linear enhancement in AVR solubility with increasing Mβ-CD concentrations. In silico analysis of the Mβ-CD/AVR inclusion complex confirmed that AVR drugs show potential as inhibitors of SARS-CoV-2 3C-like protease (3CLpro) receptors. Results obtained using the PatchDock and FireDock servers indicated that the most favorable docking ligand was Mβ-CD:AVR, which interacted with SARS-CoV-2 (3CLPro) protease inhibitors with high geometric shape complementarity scores (2522 and 5872) and atomic contact energy (-313.77 and −214.70 kcal mol−1). Our results suggest that the Mβ-CD/AVR inclusion complex inhibits the main protease of SARS-CoV-2, although further wet-lab experiments are needed to verify these findings.

An Open Inquiry Lab Experiment Preparing Bis(N,N-diethylethylenediamine) Nickel(II) Complexes

Starting with a double replacement reaction in alcohol between Ni(H2O)6(NO3)2 and NaX, students exploit solubility differences to produce a solution of NiX2 and a NaNO3 precipitate. They then synthesize a bis(N,N-diethylethylenediamine) Ni(II) complex with chloride, bromide, iodide, thiocyanate, acetate, nitrate, or perchlorate. Infrared spectroscopy provides very useful characterization information, especially when comparing different complexes between students. The solid complexes have different colors. Some of the complexes are high spin, and some are low spin. Students combine class data to correlate the color of the compound, magnetic susceptibility measurements, and expectations from ligand-field theory for d8 tetragonally distorted octahedral and square planar complexes. This is an open inquiry laboratory experience because students are only provided with generic instructions, students are responsible for planning what to work on next, and students modify or repeat steps as needed based on their infrared spectroscopy measurements.

Stable Phase Equilibria in the Quaternary Systems LiBr–NaBr–SrBr2–H2O and LiBr–KBr–SrBr2–H2O at 288.15 K

Aiming at the composition of underground brines in the Sichuan Basin of China, stable phase equilibria in quaternary systems LiBr–NaBr–SrBr2–H2O and LiBr–KBr–SrBr2–H2O at 288.15 K are studied using the isothermal dissolution equilibrium method. The solubilities of salts in the quaternary systems listed above are measured, and the corresponding equilibrium solid phases are identified using X-ray powder diffraction. As a result, the corresponding phase diagrams of the two quaternary systems are plotted, respectively. In the two stable phase diagrams, there is no solid solution or complex salt at 288.15 K. For the quaternary system LiBr–NaBr–SrBr2–H2O, there are two invariant points, five univariate curves, and four solid crystallization regions, which are LiBr·2H2O, NaBr, NaBr·2H2O, and SrBr2·6H2O, respectively, of which LiBr·2H2O has the smallest crystallization field, indicating that its solubility is the largest and it is the hardest to be precipitated from the saturated solution. There are one invariant point, three univariate curves, and three solid crystallization fields, corresponding to LiBr·2H2O, KBr, and SrBr2·6H2O in the quaternary system LiBr–KBr–SrBr2–H2O, respectively. The experimental results show that the solubilities of salts KBr, NaBr, and SrBr2 in the saturated solution decrease with the increasing concentration of LiBr, which indicates that LiBr has a strong salting out effect on KBr, NaBr, and SrBr2 in the solution.

The Role of Excipients in Liquisolid Technology

This article gives criteria for choosing excipients in liquisolid technology. Liquisolid technology is applicable for non polar drugs by converting drug solution into dry free flowing powder. Patient compliance is more in oral route of administration .Numerous techniques like solid dispersion, micronisation, lyophilisation co-grinding, co-precipitation,complexation and nanotechnology are used to increase aqueous solubility Solid dispersion having stability issues while micronization and complexation can cause agglomeration. In Nanotechnology, high cost involved in sophicticated instruments. Liquisolid technology is considered to be one of the best technique to to overcome solubility,dissolution and bioavailability. It convert drug solution into dry free flowing powder. This technique is simple manufacturing process with low production cost. In vitro release is enhanced by using this technology. There is significant role of excipients in this novel technique to get effective release of drug. Associated problems of BCS class II and IV is mostly solved in respect to solubility. Especially carrier with high specific surface area gives good results in overcoming all challenges. Carriers such as Lactose, Starch, Avicel pH101,Fujacilin, Neusilin ,each having specific properties in release of drug. Among all mostly used carriers are Avicel, Fujacilin and Neusilin as with highest Specific Surface Area (SSA) than others. PVP and SSG is considered best disintegrating agent as having good swelling property and flow property as Polyvinypyrrolidine can be used in high dose drugs. With large SSA and high adsorptive property Neusilin, Aerosil , PVP as carrier, coating material and disintegrating agent are considered perfect excipients in liquisolid technology.

Characterization, DFT, and antimicrobial evaluation of some new N2O2 tetradentate Schiff base metal complexes

Fe (III), Co (II), Ni (II), Cu (II), Y (III), Zr (IV), La (III), and U (VI) interact with Gat‐o‐phdn Schiff base (4E,4′E)‐4,4′‐(1,2‐phenylenebis (azaneylylidene))bis(1‐cyclopropyl‐6‐fluoro‐8‐methoxy‐7‐(3‐methylpiperazin‐1‐yl)‐1,4‐dihydroquinoline‐3‐carboxylic acid to produce cationic mononuclear complexes. The isolated solid complexes were characterized with physicochemical, spectroscopic techniques (FT‐IR, UV–Vis and 1H NMR), mass spectrometry, and thermogravimetric analyses. The infrared data indicated that Gat‐o‐phdn acting as tetradentate ligand chelated to the metal ions through the carboxylate oxygen and the nitrogen of azomethine group. The metal ions complete the coordination number with water molecules. The mechanism of the thermal decomposition was detected, and the kinetic parameters of the dissociation steps were evaluated using Coats–Redfern (CR) and Horowitz–Metzger (HM) methods. Bond lengths, bond angles, total energy, heat of formation, dipole moment, and the lowest energy model structures have been determined using density functional theory (DFT) calculations. The synthesized ligand and its complexes were screened for antimicrobial activities against two Gram‐positive bacteria, two Gram‐negative bacteria, and two fungi. The Cu (II) complex was very highly significant against Staphylococcus aureus compared with free Gat‐o‐phdn and references standard control. Also, it showed the highest antibacterial effects compared with all complexes.

Clusterin Binding Modulates the Aggregation and Neurotoxicity of Amyloid-β(1-42).

Alzheimer's disease (AD) is the most common neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) aggregates in the brain. Clusterin (CLU), also known as apolipoprotein J, is a potent risk factor associated with AD pathogenesis, in which Aβ aggregation is essentially involved. We observed close colocalization of CLU and Aβ(1-42) (Aβ42) in parenchymal amyloid plaques or vascular amyloid deposits in the brains of human amyloid precursor protein (hAPP)-transgenic Tg2576 mice. Therefore, to elucidate the binding interaction between CLU and Aβ42 and its impact on amyloid aggregation and toxicity, the two synthetic proteins were incubated together under physiological conditions, and their structural and morphological variations were investigated using biochemical, biophysical, and microscopic analyses. Synthetic CLU spontaneously bound to different possible variants of Aβ42 aggregates with very high affinity (Kd = 2.647nM) in vitro to form solid CLU-Aβ42 complexes. This CLU binding prevented further aggregation of Aβ42 into larger oligomers or fibrils, enriching the population of smaller Aβ42 oligomers and protofibrils and monomers. CLU either alleviated or augmented Aβ42-induced cytotoxicity and apoptosis in the neuroblastoma-derived SH-SY5Y and N2a cells, depending on the incubation period and the molar ratio of CLU:Aβ42 involved in the reaction before addition to the cells. Thus, the effects of CLU on Aβ42-induced cytotoxicity were likely determined by the extent to which it bound and sequestered toxic Aβ42 oligomers or protofibrils. These findings suggest that CLU could influence amyloid neurotoxicity and pathogenesis by modulating Aβ aggregation.

Preparation, characterization and photocatalytic properties of rare-earth ibuprofen-phenanthroline complexes

In this experiment, europium(III)-ibuprofen-phenanthroline complexes, dysprosium(III)-ibuprofen-phenanthroline complexes and terbium(III)-ibuprofen-phenanthroline complexes were prepared separately, established a ternary solid complex system, performed a series of characterization of the system, and studied the application of the rare-earth-ibuprofen-phenanthroline complex system. In the experiment, the three ternary complexes were characterized by elemental analysis, infrared analysis, ultraviolet analysis, fluorescence analysis, thermogravimetric analysis, etc., and the chemical composition of the complexes was determined, and the data and spectra obtained were analyzed. The rare-earth ternary complex was successfully prepared by a simple and feasible method. The analysis results found that the characteristics and performance of the ternary complex were enhanced, and its physical and chemical properties were explored. The successful preparation of rare earth-ibuprofen-phenanthroline ternary complexes provides a certain scientific basis and reference for the study of determining the content of ibuprofen (IBU) in vitro, and also provides a new method for the synthesis of rare-earth ternary complexes. The reason why rare-earth materials can be used as catalysts is determined by their own photoelectric characteristics. In this paper, through the experimental test of catalytic performance of IBU and different rare-earth complexes, it is found that Tb complex has the best catalytic performance, and the degradation rate of phenol can reach 64.8% in 6 h.

Design and Evaluation of Orally Dispersible Tablets Containing Amlodipine Inclusion Complexes in Hydroxypropyl-β-cyclodextrin and Methyl-β-cyclodextrin

The development of new orally dispersible tablets containing amlodipine (AML) inclusion complexes in hydroxypropyl-β-cyclodextrin (HP-β-CD) and in methyl-β-cyclodextrin (Me-β-CD) was studied. The methods of obtaining amlodipine and the physical and chemical properties of the inclusion complexes using the two cyclodextrins was investigated separately. Solid inclusion complexes were obtained by three methods: kneading, coprecipitation, and lyophilization, at a molar ratio of 1:1. For comparison, a physical mixture in the same molar ratio was prepared. The aim of the complexation process was to improve the drug solubility. As the lyophilization method leads to a complete inclusion of the drug in the guest molecule cavity, for both used cyclodextrins, these types of compounds were selected as active ingredients for the design of orally dispersible tablets. Subsequently, the formulation of the orodispersible tablets containing AML-HP-β-CD and AML-Me-β-CD inclusion complexes and quality parameters of the final formulation were evaluated. The results prove that F1 and F4 formulations, based on silicified microcrystalline cellulose, which contains insignificant proportions of very small or very large particles, had the lowest moisture degree (3.52% for F1 and 4.03% for F4). All of these demonstrate their porous structure, which led to good flowability and compressibility performances. F1 and F4 formulations were found to be better to manufacture orally dispersible tablets.

Preparation, binding behaviours and thermal stability of inclusion complexes between (Z)‐jasmone and acyclic cucurbit[n]urils

Abstract(Z)‐jasmone is the most important contribution to the scents of perfumes and cosmetics. However, (Z)‐jasmone is water insoluble and highly volatile, which limits its development and application. Inclusion technology has become a promising strategy to improve the solubility and stability of hydrophobic small molecules. Here, we used saturated aqueous solution and freeze‐drying method to prepare solid inclusion complexes of (Z)‐jasmone and three acyclic cucurbit[n]urils (ACBs, M1‐M3), and studied their binding behaviours by fluorescence spectroscopy, NMR, XRD, FT‐IR, TG and DSC, confirming the formation of the host‐guest inclusion complexes. The stoichiometry of inclusion complexes was 1:1 by Job's plot. The inclusion complexes exhibited better water solubility, higher thermal stability and heat‐controlled release comparing with that of native (Z)‐jasmone. This work uncloses a new strategy to enhance the performance of essential oil and flavours/fragrances and further application in the field of cosmetic and food industry.

Lorentz-Force-Mediated Zn Electrodeposition and Br- Ion Convection for Improved Performance in Aqueous Zn-Br2 Static Batteries

Redox flow batteries are one of the prominent electrochemical energy storage devices with large-scale storage and high energy density.1 The highly reversible Zn/Zn2+ (-0.76 V vs. RHE) and Br-/Br2 (1.08 V vs. RHE) redox couple have been employed in Zn-Br2 flow batteries (1.84 V vs. RHE). However, the dendritic growth of Zn electrodeposits during the repetitive discharge process triggers an internal short-circuit between the anode and the cathode.1 Besides this, cross-diffusion of the highly soluble Br- (Br3 -) ion causes a severe self-discharge of the system and reduced cycle life.2 Additives and ion-selective membranes have been employed to mitigate these challenges for improved cycle life and coulombic efficiency in Zn-Br2 batteries.3 Here, we fabricate an aqueous Zn-Br2 static battery with internally contained and moderate magnetic fields, (~ 30, 40, 50 and 60 mT) at the anode and cathode by incorporating 1 mm thick Nd permanent magnets. A solid complex of tetrapropylammonium tribromide was supported on activated carbon and employed as the positive electrode. Introducing a magnetic field can generate the Lorentz force (acting on Br- and Zn2+ ions), and create a controllable magnetohydrodynamic mass transport during the charge-discharge processes. Among the various magnetic fields, ~50 mT resulted in the highest coulombic efficiency (99 % for 100 cycles) and suppressed Zn dendritic growth. To rationalize the effect of magnetic fields on the efficiency and cycle life, Raman analysis, X-ray diffraction, scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry (for the calculation of diffusion coefficient of Br- ion) are performed on the positive and negative electrodes of Zn-Br2 battery.

A Review of Various Pharmacological Effects of Quercetin with its Barriers and Approaches for Solubility and Permeability Enhancement

Background: Quercetin, one of the most beneficial flavonoids, has been included in the human diet due to its therapeutic effect on health. Recently, quercetin has been gaining scientific attraction for its multifarious activities, including anti-oxidant, anti-inflammatory, antiviral, anti-diabetic, anti-cancer, and anti-arthritic activities and its function in easing some cardiovascular diseases. However, these applications of quercetin in the pharmaceutical field are limited due to its poor aqueous solubility and poor permeability. Objective: The present review summarizes various pharmacological activities of quercetin, analyzes the barriers like solubility and permeability, which restrict the therapeutic efficiency of quercetin, and also discusses novel approaches to enhance aqueous solubility and permeability of quercetin for its effective clinical use. Methods: The current review information sources were peer-reviewed relevant scientific articles of recognized journals from scientific engines and databases (Scopus, Web of Science, PubMed, Science Direct, Google Scholar) using different keywords related to quercetin pharmacological effects, mechanism, solubility, permeability, absorption barriers, and formulation approaches. Results: Various novel approaches, including solid dispersions, inclusion complex, pro-drugs, nanoemulsion, micelles, liposomes, SNEEDS, and microspheres, have been developed to overcome the solubility and permeability barriers for efficient quercetin delivery. Conclusion: This review revealed that the multifaceted pharmacological activities of quercetin for the management of various diseases are enormously dependent on the development of novel and safe drug delivery systems of quercetin.

Synthesis and Characterization of some Transition Metals Complexes with new Ligand Azo Imidazole Derivative

AZO complexes synthesized by binding metal ions as Mn(II), Co(II), Ni(II) and Cu(II), with the ligand (L) [ethyl 4-((E)-(5-oxo-1-(((1E,2E)-3-phenylallylidene)amino)-2-thioxo-2,5-dihydro-1H-imidazol-4-yl)diazenyl)benzoate] was prepared from three steps ,first step preparation Schiff base product of condensation reaction by reaction Thiosemicarbazide with cinnamaldeyde, second step preparation the Imidazole ring close by reaction ligand 1 with chloroethylacetate, finally preparation Azo ligand(Diazanium compound) by reaction ligand 2 with benzocain. Characterized the ligands and complexes in their solid state using the elemental micro analysis (C.H.N.S), flame atomic absorption. UV-vis spectroscopy, FT-IR, magnetic susceptibility measurements, Mass spectrum, 1H-NMR spectra and electrical molar conductivity. These techniques produced comparable results with those obtained for the solid complexes. From the data of all techniques, octahedral geometry was proposed for Mn(II), Co(II), Ni(II) and Cu(II) complexes.

Surfactant–solid complex for enhancing the flow in pipelines: an experimental approach

BackgroundViscoelastic soluble polymeric additives have been used successfully for a long time as drag reducers in pipelines carrying commercial liquids like crude oil. Most of these polymers suffer from irreversible degradation when exposed to high shearing zones as in valves, elbows, and pumps which reduces, or eliminates, its flow enhancement effect. Insoluble additives were proven to be an effective drag reducer that overcomes the degradation drawback of soluble additives. On the other hand, insoluble additives suffer from the lack of viscoelasticity which limits their use as flow enhancers. The creation of complexes from soluble and insoluble additives is a field of research that is rarely explored despite its importance in introducing new flow enhancement methods for a higher drag reduction performance. The present work introduces a new surfactant–solid complex as a drag-reducing agent for turbulent flow in pipelines.ResultsThe surfactant, solid, and their complexes’ drag reduction performance was tested in a closed-loop turbulent flow liquid circulation system, while rheological characteristics of the soluble additives were tested using a standard rheometer. All the surfactant solutions showed non-Newtonian shear thinning behavior in all the investigated concentrations that ranged between 500 and 1300 wppm. The initial experimental result indicated that the surfactant solution's drag reduction performance was higher than that of the solid suspensions. On the other hand, the drag reduction performance was enhanced by 52% when creating a 1300 wppm surfactant–2000 wppm solid complex. This improvement in the drag reduction performance is due to the formation of surfactant–solid-enforced aggregates with high resistance to shear forces and high turbulence suppression efficiency.ConclusionsThe present work introduces a new drag reduction solid–surfactant complex by creating aggregates combining the viscoelastic properties of surfactants with the resistance to high shear forces exerted by the solid particles. The polar nature of the surfactant micelles that form in single-phase flow systems contributed significantly to trapping the solid's micro-particles as enforcement to resist the shearing forces applied by the turbulent flow system.