Powder X-ray Diffraction Studies Research Articles

Luminescence properties of Eu3+ doped Li2SrSiO4 phosphor

The modified solid-state reaction method has been used in this work to prepare Eu3+ doped Li2SrSiO4. PL spectroscopy was used to investigate photoluminescence (PL) properties of the sample. X-ray powder diffraction study was used to confirm the crystalline nature and phase purity of the sample. The particle size of prepared material ranges from 37 to 56 nm was observed from XRD. From PLE and PL spectrum the excitation and emission spectra of photoluminescence for Eu3+ doped Li2SrSiO4 were recorded. The prepared Eu3+ doped Li2SrSiO4 phosphor might have application in solid state lighting.

Preparation and Evaluation of Aceclofenac Solid Dispersion by Fusion Technique and Effervescent Assisted Fusion Technique: Comparative Study

Solid dispersion (SD) is one of the most widely used methods to resolve issues accompanied by poorly soluble drugs. The present study was carried out to enhance the solubility and dissolution rate of Aceclofenac (ACE), a BCS class II drug with pH-dependent solubility, by the SD method. Effervescent assisted fusion technique (EFSD) using different hydrophilic carriers (mannitol, urea, Soluplus®, poloxamer 188, and poloxamer 407) in the presence of an effervescent base (sodium bicarbonate and citric acid) in different drug: carrier: effervescent base ratio and the conventional fusion technique (FSD) were used to prepare ACE SD. Solubility, dissolution rate, Fourier transformation infrared spectroscopy (FTIR), PowderX-ray diffraction study (PXRD), and Differential scanning calorimetry (DSC) were determined for the SD obtained from both techniques as a comparative study. The results showed that EFSD using ACE: Soluplus®: effervescent base in a ratio of 1:2:1 had higher solubility and dissolution rate than that obtained from FSD prepared by ACE: Soluplus® in a ratio of 1:2. However, the two techniques obtained the amorphous form according to XRD and DSC results. It can be concluded that EFSD is a promising method for the solubility and dissolution rate improvement of BCS class II drugs.

Considerations for quantitative in situ X-ray powder diffraction studies of solid-state reactions

The importance of sample preparation in collecting high-fidelity powder diffraction data suitable for quantitative structure and phase analysis is well established. Such powder diffraction experiments are increasingly being applied in situ, during reactions, to explore solid-state reactivity. When applied in situ, X-ray diffraction is widely used to gain insight into the mechanism and kinetics, and to identify dynamic intermediate states. Here, using a model ion-exchange reaction (NaFeO2 + LiCl → LiFeO2 + NaCl), we show that sample preparation not only influences the fidelity of powder diffraction analysis but also impacts the observed reaction progress. Specifically, we found that the observed reaction progress can differ by ∼50% depending on the capillary sample preparation. Thus, for in situ diffraction studies of solid-state reactions, packing fraction is an important and previously unrecognized consideration that impacts reproducibility and fidelity of the reaction study.

Structural and vibrational properties of cage-type Sc5Ru6Sn18 superconductor under pressure using synchrotron X-ray diffraction and Raman spectroscopy

We report detailed structural investigations of cage-type quasi-skutterudite compound Sc5Ru6Sn18 using synchrotron single-crystal and powder x-ray diffraction. Single-crystal x-ray diffraction studies at ambient temperature revealed that the Sc5Ru6Sn18 compound has a tetragonal symmetry in the I41/acd space group setting with a = 13.58Å and c = 27.14Å, similar to other R5Rh6Sn18 (R = Y, Sc, Lu) cage-type compounds. The electrical resistivity ρ(T) revealed the presence of a sharp superconducting (SC) transition at Tc = 4.07K. The ρ(T) of Sc5Ru6Sn18 above Tc shows a smooth decrease with decreasing temperature without any evident anomalies. Systematic temperature dependent synchrotron x-ray powder diffraction (XRPD) studies covering 400 to 110K shows that the Sc5Ru6Sn18 system remain in the tetragonal I41/acd structure in this temperature range without any anomalous behaviour in the unit-cell parameters. High-pressure (HP) synchrotron XRPD revealed a smooth reduction in the unit-cell parameters up to ~7GPa which can be well described by a third-order Birch-Murnaghan equation providing the bulk modulus of the system to be ~102.6GPa. This system is found to several Raman modes below 300cm-1. We could follow the pressure evolution of four Raman modes, all of which show a smooth hardening with pressure up to ~7GPa. Our results call for systematic HP studies of the SC properties of the title system.

Solubility and Dissolution Enhancement of Atorvastatin Calcium using Phospholipid Solid Dispersion Technique

Atorvastatin (ATR) is a poorly water-soluble anti-hyperlipidemic drug. The drug belongs to the class II group according to the biopharmaceutical classification system (BCS) with low bioavailability due to its low solubility. Solid dispersion is an effective technique for enhancing the solubility and dissolution of drugs. Phospholipid solid dispersion (PSD) using phosphatidylcholine (PC) as a carrier with or without adsorbent (magnesium aluminum silicate, silicon dioxide 15nm, silicon dioxide 30nm, calcium silicate) was used to prepare ATR PSD using different drug: PC: adsorbent ratios by solvent evaporation method. The resulted PSD was evaluated for its percentage yield, drug content, solubility, dissolution rate, Fourier transformation infrared spectroscopy (FTIR), powder X-ray diffraction study (PXRD), and differential scanning calorimetry (DSC). The prepared (PSD) showed improvement in drug solubility in all prepared formulas. The best result was obtained with F5 (ATR: PC: MAS 1:3:4). The solubility was increased by 21 folds compared to the pure drug with enhanced dissolution and decrease crystallinity.

Thermodynamic analysis and in situ PXRD study of mineralogy phase transformation of arsenopyrite in acid pressure oxidation

Acid pressure oxidation (POX) is a cost-efficient pre-treatment method for releasing refractory gold from arsenopyrite and pyrite prior to cyanidation. However, ongoing debate surrounds the mechanism of the dissolution, crystallization, and phase transformation during POX, in part due to the lack of thermodynamic data and in situ studies of the acid POX. In this study, we developed Eh-pH diagrams and used in situ powder X-ray diffraction (PXRD) to investigate mineralogical phase changes during acid POX of arsenopyrite. Based on the existing thermodynamic data, we established the Eh-pH diagrams for the Fe-As-S-H2O systems at 225 °C and 100 °C, which correctly predicted the predominant solid phases precipitating during POX of arsenopyrite at a pH range of 0 to 0.5, such as basic ferric sulphate (BFS: Fe(OH)SO4), szomolnokite (FeSO4·H2O), hydronium jarosite ((H3O)Fe3(SO4)2(OH)6) and angelellite (Fe4O3(AsO4)2). FeSO4·H2O solid is the stable phase during annealing stages as predicted by the Eh-pH diagram, which is in line with the observed solid phases using in situ PXRD. The influence of initial concentration of ferric ions and the presence of pyrite on mineral phase change was revealed. Our results confirmed the formation of FeSO4·H2O, BFS and hydronium jarosite during annealing stages, while BFS and/or hydronium jarosite dissolved during curing and cooling process. Especially, the formation of angelellite was observed in the presence of pyrite during cooling process, which is well-agreed with thermodynamic analysis.

SOLID DISPERSION SYSTEMS OF POORLY WATER SOLUBLE DRUG FEBUXOSTAT: PREPARATION, CHARACTERIZATION AND OPTIMIZATION

Febuxostat is a poor soluble drug used in the management of hyperuricemia and gout. The present study aims at increasing the solubility of febuxostat by solid dispersion technique with the aid of various polymers (Beta cyclodextrin, Soluplus®, HPMC E5, and Kolliphor® P 407) in various drug: carrier ratios employing the solvent evaporation method. Solid dispersions were evaluated for physical appearance, percentage yield, drug content, saturation solubility and dissolution properties. Saturation solubility data of the study depict an increased solubility of the solid dispersion compared to the pure drug. In in vitro release profiles revealed that formulation SD20, having drug: Kolliphor® P 407 in 1:9 ratio exhibited highest dissolution rate. The powder X-ray diffraction study and scanning electron microscopy (SEM) exhibited a crystalline to an amorphous transformation in the solid dispersion. The study demonstrated that solid dispersions are a highly effective technique to increase solubility and bioavailability of febuxostat.

Development of Chitosan/Sodium Carboxymethylcellulose Complexes to Improve the Simvastatin Release Rate: Polymer/Polymer and Drug/Polymer Interactions' Effects on Kinetic Models.

Simvastatin (SIM) is a potent lipid-lowering drug used to control hyper-cholesterolemia and prevent cardiovascular diseases. SIM presents low oral bioavailability (5%) because of its low aqueous solubility. In this work, polyelectrolyte complexes (PEC) are developed with different chitosan (CS) and carboxymethylcellulose (CMC) ratios that will allow for an increase in the SIM dissolution rate (2.54-fold) in simulated intestinal medium (pH 4.5). Scanning Electron Microscopy (SEM) images revealed highly porous structures. The changes between both complexes, PEC-SIM:CS:CMC (1:1:2) and (1:2:1), were related to the relaxation of the polymer chains upon absorption of the dissolution medium. Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and powder X-ray diffraction (XRPD) studies were used to evaluate the polymer/polymer and drug/polymer interactions on the different PEC-SIM:CS:CMC ratios. In addition, the PEC-SIM:CS:CMC (1:2:1) complex exhibited a high ratio of protonated amino groups (NH3+) and an increase in intramolecular hydrogen bonds, which were correlated with a high expansion of the interpolymer chains and an increase in the SIM dissolution rate. Different kinetic models such as zero-order, first-order, Higuchi and Korsmeyer-Peppas were studied to evaluate the influence of CS/CMC ionic interactions on the ability to improve the release rate of poorly soluble drugs.

Effect of the Presence of Structural Defects on the Superconducting Properties of (NbTa)0.67(MoHfW)0.33 and Nb-47wt%Ti

A comparison of the results of studies on the influence of structural defects on the critical parameters of superconductivity has been made for the high-entropy alloy (NbTa)0.67(MoHfW)0.33 and for the conventional superconducting magnet material Nb-47wt%Ti. Positron annihilation lifetime spectroscopy (PALS), electrical resistivity, magnetization and magnetic susceptibility measurements were used. In addition, X-ray powder diffraction studies were performed on the high-entropy alloy (NbTa)0.67(MoHfW)0.33. Due to the rapid cooling of the materials after melting in the arc furnace, they contain a higher concentration of structural defects compared to the heat-treated materials. Magnetic property measurements showed that both the critical temperatures Tc and the upper critical fields μ0Hc2 of bulk superconductivity-related materials are improved in the presence of structural defects.

A comparative study on physico-chemical, optical, magnetic and ferroelectric properties of undoped BiFeO3 and Ni-doped BiFeO3 nanoparticles

Undoped BiFeO3 and Ni-doped BiFeO3 nanostructures were synthesised via colloidal gel, followed by a combustion reaction at a processing temperature of 500 °C, for testing their multiferrioic properties. Powder X-ray diffraction studies reveal the rhombohedral perovskite crystal structure for the synthesized pure BiFeO3, whereas Ni-doped BiFeO3 sample shows the formation of the rhombohedral perovskite structure along with the heterogeneous phase contains Fe2O3 and Bi2Fe4O9. The energy band gap (Eg) of Ni-doped BiFeO3 was found to be reduced (1.87 eV) compared to the Eg value (2.02 eV) of undoped BiFeO3, as confirmed by the Tauc plot. The synthesized compounds were tested for their vibrational bands by FT-IR analysis, and strong absorption bands were found at 555 cm−1, which attribute the vibration bonds of Bi-O and Fe-O. The aggregated particles with irregular morphology appeared in the TEM images of the undoped BiFeO3 and the presence of Ni-doped incorporation of BiFeO3. The ferromagnetic and ferroelectric behaviour of the synthesized undoped and Ni-doped BiFeO3materials was noticed in the magnetization vs. magnetic field (M−H) loops and polarization–electric field (P-E) at room temperature. The areas of the hysteresis loop, coercive force, magnetic saturation, saturation polarization, remanent magnetization, and polarization of Ni-doped BiFeO3 were decreased compared to undoped BiFeO3. The investigated Ni-doped BiFeO3 results were elucidated to assess the soft magnetic nature of device applications.

Preparation and evaluation of βcyclodextrin-based nanosponges loaded with Budesonide for pulmonary delivery

Budesonide (BUD) is a glucocorticosteroid used to treat chronic obstructive pulmonary disease. Despite this, it is a hydrophobic compound with low bioavailability. To address these hurdles, non-toxic and biocompatible βcyclodextrin-based nanosponges (βCD-NS) were attempted. BUD was loaded on five different βCD-NS at four different ratios. NS with 1,1′-carbonyldiimidazole (CDI) as a crosslinking agent, presented a higher encapsulation efficiency ( ̴ 80%) of BUD at 1:3 BUD: βCD-NS ratio (BUD-βCD-NS). The optimized formulations were characterized by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), water absorption capacity (WAC), scanning electron microscopy (SEM), X-ray powder diffraction studies (XRD), particle size, zeta potential, encapsulation efficiency, in vitro and in vivo release studies, acute toxicity study, solid-state characterization, and aerosol performance. In vitro-in vivo correlation and cytotoxicity of the formulations on alveolar cells in vitro were further determined. In vitro and in vivo studies showed almost complete drug release and drug absorption from the lungs in the initial 2 h for pure BUD, which were sustained up to 12 h from BUD loaded into nanosponges (BUD-βCD-NS). Acute toxicity studies and in vitro cytotoxicity studies on alveolar cells proved the safety of BUD-βCD-NS. Several parameters, including particle size, median mass aerodynamic diameter, % fine particle fraction, and % emitted dose, were evaluated for aerosol performance, suggesting the capability of BUD-βCD-NS to formulate as a dry powder inhaler (DPI) with a suitable diluent. To sum up, this research will offer new insights into the future advancement of βCD-NS as drug delivery systems for providing controlled release of therapeutic agents against pulmonary disease.

Clove bud extract mediated green synthesis of bimetallic Ag–Fe nanoparticles: Antimicrobial, antioxidant and dye adsorption behavior and mechanistic insights of metal ion reduction

Metal nanoparticle synthesis by metal ion reduction from plant extract has paid immense attention to researchers owing to its low cost, easy synthesis and eco-friendly nature compared to other biological methods. Compared to monometallic nanoparticles, syntheses of bimetallic nanoparticles have great importance due to the possibility of better performance of bimetallic nanoparticles compared to their monometallic counterpart. To explore this possibility, we synthesized bimetallic Ag–Fe nanoparticles of different compositions using aqueous phase co-reduction of Ag+ and Fe3+ metal ions in different ratios by clove (Syzygium aromaticum) flower bud extract. Prepared nanoparticles were characterized by Ultraviolet–visible spectroscopy, powder X-ray diffraction and Scanning Electron Microscopic studies, etc. All bimetallic nanoparticles exhibited multifaceted applications as antimicrobial agents, antioxidants and dye adsorbents. Among the different nanoparticles, bimetallic nanoparticles having Ag–Fe ratio 80:20 exhibit better performance for antimicrobial and dye adsorption activity than mono as well as other bimetallic nanoparticles. As depicted by the powder X-ray diffraction study, the synergy between metals is attributed to the prevention of oxidation of silver to silver oxide in the presence of iron. However, antioxidant activity is directly related to silver content as both silver and silver oxide exhibit almost similar antioxidant properties. The synergy between the metals in bimetallic nanoparticles provided the opportunity to enhance the activity of nanomaterials for various applications along with lowering the cost. Besides the synthesis and activity study of bimetallic nanoparticles, we tried to provide theoretical evidence for the mechanism of metal ion reduction by Eugenol (a major phytochemical present in the clove extract). Structural optimization and thermodynamic parameter calculation using DFT methods suggest that eugenol is preferred to oxidize itself and theoretically calculated reduction potential is ∼ -3.40V at 300K in the gaseous phase.

Phenylalanine-Based Co2+ and Cd2+ 1D Coordination Polymers: Structural Properties and Catalytic Application for Solvent-Free Aerobic Oxidation of Cycloalkene.

Two 1D coordination polymers (CPs) with general formula [M(L)(H2O)(AcO)]n, (M = Co (1) or Cd (2), AcO = acetate anion and L denotes l-phenylalanine based ligand), were synthesized and fully characterized by various spectroscopies (UV-vis, FTIR, and NMR), thermal techniques, magnetic measurements (for 1), and single-crystal and powder X-ray diffraction studies. They can be described as "ribbon-like" 1D polymers constructed through a zigzag arrangement. The polymeric structure is developed due to the coordination mode adopted by the amino acid ligand, classified as μ3-N1O1:O1:O2, which simultaneously links three metal centers. This moiety also plays an important role as a magnetic coupler between metal centers in the cobalt system, which shows a weak antiferromagnetic interaction. Both CPs have also been used in the catalytic oxidation of cyclohexene with molecular oxygen (O2) as an oxidant. Under mild conditions, both compounds demonstrated remarkable catalytic activity, with the cobalt system being more efficient than the cadmium analogue (conversion: 73 and 58% and selectivity for the major product, 2-cyclohexanone: 63 and 55%, for 1 and 2, respectively). Leaching experiments and the results obtained using a radical quencher are consistent with a radical-mediated mechanism for the Co compound. The presence of the superoxide radical was also confirmed using EPR spectroscopy and DMPO as a spin trap, which was further validated by DFT calculations. The activity observed for the Cd analogue is attributed to the organic scaffold assisted by the templating effect of the metal ion.

Base-Catalyzed Polymerization of a Substituted Methylenebicyclo[3.3.1]nonane

Lignite humic acid on reaction with formaldehyde and aqueous alkali led to a polybicyclo[3.3.1]nonane. This was characterized spectroscopically using mass spectrometry, FT-IR, powder X-ray diffraction, TEM, and NMR studies (1H-NMR, CP-MAS-SS-NMR) which though challenging were useful for confirming the structure of the BCN polymer. The product showed an envelope peak in its MALDI-MS spectrum, based on which M ̅ n , M ̅ w , and polydispersity index have been calculated. Based on the NMR spectrum of intermediate, the presence of the N-formyl group has been shown in it. The new polymer could be useful in agriculture in water-deficient areas. Most papers on humic acids include only broad and general information like elemental analysis (occasionally TEM, SEM, TGA, DSC, etc.). Very complicated structures have been proposed by scientists earlier. Only in very recent years, it has been recognized that these are relatively small molecules which masquerade as supramolecular structures. It is pointed out that most papers do not put down the structure of the compound and provide no concrete proof for proposing such structures. The novelty of our work is that we have characterized the precise molecular weights based on mass spectrometry and NMR spectroscopy along with a well-defined structure. This is not the case in most other publications.

A comprehensive study on synthesis, growth and characterization of Guanidinium 4-chloro-3-nitrobenzoate monohydrate (G4C3NBM) single crystal for NLO applications: A third order nonlinear optical material

The growth of guanidinium and benzoic acid based single crystal Guanidium 4‑chloro-3-nitrobenzoate monohydrate (G4C3NBM) was carried out via the process of slow evaporation using mixed solvents (water and ethanol). G4C3NBM crystals were obtained and multiple characterization techniques have been taken into consideration. To ascertain G4C3NBM crystal's structure, Single Crystal X-ray Diffraction (SXRD) study was performed and thereby cell parameter values were computed. The crystalline nature of G4C3NBM was elucidated by Powder X-ray Diffraction (PXRD) study. Fourier Transform Infrared Spectroscopy (FTIR) study was executed to know the vibrational assignments of G4C3NBM crystal. The linear optical properties of G4C3NBM crystal were investigated through UV–visible–NIR analysis. In addition, Photoluminescence (PL) spectra exhibited the emission characteristics of the crystal. The thermal stability of G4C3NBM was probed by utilizing TGA -DTA study. The Nd-YAG Laser (1064 nm) was employed to assess target crystal's Laser Damage Threshold (LDT) and a comparison was performed with other similar NLO crystals. The mechanical nature and various mechanical parameters were determined with the help of Vickers's Micro Hardness Test. A Z-Scan method was put to use to delve into the third order nonlinearities of G4C3NBM crystal and computations of all the related parameters were carried out. The promising results of the above studies and work performed indicate the excellent potential possessed by Guanidinium 4‑chloro-3-nitrobenzoate monohydrate (G4C3NBM) crystal for use in NLO applications.

Growth of high carrier mobility 2-Dimensional hexagonal Bi2Te3-xSex nanoplatelets and its thermoelectric performance studies

Morphologically controlled growth of selenium-doped 2-Dimensional (2D) Bi2Te3-xSex nanoplatelets have been optimized by solvothermal synthesis using polyvinyl-pyrro-lidone (PVP) surfactant from the pre-optimized growth conditions of 2D-Bi2Te3 hexagonal nanoplatelet. An optimization was carried out using the Se-doping of x = 0.3 under variable growth durations of 4 h, 8 h, and 12 h. X-ray powder diffraction studies confirmed the complete crystallization with a pure phase of 2D-Bi2Te3-xSex at an extended duration of 12 h synthesis. Crystallization with defined hexagonal morphology was confirmed by FESEM analysis. Selenium doping into the 2D-Bi2Te3-xSex lattice from x = 0.1 to x = 0.4 indicates a step-by-step shift in the 2θ value of the (015) predominant peak towards higher 2θ values. Raman analysis revealed the alteration of the appearance of A1u2 to A1g2 upon the lattice inclusion of “Se” in the place of “Te”. Hall measurements on the consolidated pellet of 2D-Bi2Te3-xSex resulted in the highest electron mobility of 1675 cm2V−1s−1 with carrier concentration of 2.9 × 1018 cm−3 for Se-doping x = 0.2. Thermal conductivity analysis in comparison with the total thermal conductivity and the calculated electronic thermal conductivity revealed the lowest lattice thermal conductivity of 0.17 Wm−1K−1 for the Se-doping x = 0.2 after the correction for structural anisotropy factor (f). The highest thermoelectric figure of merit of 0.74 was achieved in this course of work.

Quest for iron(III) isoporphyrins: Synthesis, characterization, reactivity and theoretical studies

Detailed studies on iron(III) isoporphyrins, which are isoelectronic with iron(IV)-oxo porphyrin radical and very much reactive in nature are rare in the literature. Therefore, here we have reported the synthesis of a series of methoxy iron(III) isoporphyrins of tetraphenylporphyrin derivatives using chemical oxidants and characterized well with UV–Visible, IR, ESI-Mass, elemental analysis, thermal gravimetric studies (TGA), Powder X-Ray Diffraction studies and 1H NMR spectroscopy. The electrochemical studies were performed for the first time on such type iron(III) isoporphyrins. ESR and magnetic susceptibility studies supported the high-spin iron(III) nature of the isoporphyrins. For the first time, theoretical studies like geometry optimization, simulation of optical spectra, and energy calculations were performed on a methoxy isoporphyrin of simple [FeIII(TPP)Cl] (Iron(III) tetraphenyl porphyrin) using the density functional theory method to understand the typical electronic, redox and highly reactive nature of iron isoporphyrins. The theoretical calculations supported the strong absorptions at the near-IR region in electronic spectra, very reactive nature and typical redox behavior of iron(III) isoporphyrins.

Synthesis, spectroscopic characterization, in vitro antimicrobial activity, antioxidant study and theoretical approaches towards DNA gyrase, DHFR enzyme, NADPH enzyme of N8-tetraoxomacrocyclic complexes of Zn(II)

In the present work, novel N8-tetraoxomacrocyclic complexes of Zn(II) were synthesized from macrocyclic ligands (N8O4L1- N8O4L3) in a 1:1 zinc chloride to macrocyclic ligand ratio in methanol solvent. The structure of the newly synthesized compounds was confirmed by elemental analysis, infra-red (IR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, high-resolution mass spectrometry (HR-MS), UV–visible spectroscopy, and powder X-ray diffraction (XRD) studies. The spectral data indicated that macrocyclic ligands (N8O4L1- N8O4L3) functioned as tetradentate ligands, which coordinated to Zn(II) ions through the nitrogen atom of imine (>CN) group. Two chloro groups are covalently bound to Zn(II) ions, which are responsible for an octahedral environment around the zinc in macrocyclic complexes. Density functional theory (DFT) calculations were performed to support the resulting proposed octahedral structure and also to calculate the quantum chemical parameters. Subsequently, the macrocyclic compounds were examined against a panel of pathogenic microbes including Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and fungal strains (Aspergillus niger and Candida albicans) for their in vitro antimicrobial potential. The result showed that the macrocyclic complexes have remarkable antimicrobial potential as compared to their corresponding macrocyclic ligands at the same concentration. Then, the synthesized compounds were evaluated for their ability to scavenge free radicals using DPPH assay. The result showed that the macrocyclic complex [Zn(N8O4L3)Cl2] exhibited higher antioxidant efficacy among all the tested macrocyclic compounds with IC50 value 0.22 ± 0.025 mg/mL, relative to ascorbic acid (IC50 value = 0.12±0.01 mg/mL). Furthermore, molecular docking studies were performed to predict the exact binding mode of the newly synthesized compounds to the specified target proteins DNA gyrase (PDB ID 4DHU), DHFR enzymes (PDB ID 4HOF), and NADPH enzyme (PDB ID 2CDU). From the molecular docking studies, it was observed that the molecular docking results are in good agreement with the in vitro biological studies. Hence, it is concluded that macrocyclic ligands and their Zn(II) complexes have the potential to be explored as active antimicrobial and antioxidant agents.

Au nanoparticles dispersed polypyrrole-carbon black/SrTiO3 nanocomposite photocatalyst with rapid and stable photocatalytic performance

The current chaotic environmental situation especially water pollution prerequisites efficient novel photocatalysts for the proper treatment of these toxic structures through advanced oxidation process. However, the development of active photocatalytic structures requires further committed effort to ensure proper designing and essential band gap. In this report, an attempt has been made to fabricate a rapid and efficient photocatalyst based on SrTiO3 nanostructures, polypyrrole doped carbon black (PPyC) and Au nanoparticles to tackle serious problems of water contamination. Au@PPyC/SrTiO3 ternary photocatalyst was smoothly fabricated by sol gel route followed by ultrasonication and photoreduction technique. X-ray powder diffraction (XRD) studies revealed that SrTiO3 have cubic perovskite structure, while X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of ternary framework among Au, PPyC and SrTiO3 nanostructures. Transmission electron microscopy (TEM) revealed that SrTiO3 possessed irregular porous nanoparticles ranging from 10 to 100 nm, whereas the PPyC appeared as well-ordered chain of beads or interconnected branches of nanoparticles. Modification of bare SrTiO3 to Au@PPyC/SrTiO3 significantly increases the surface area to 2.48 times than that of SrTiO3. The photocatalytic performance of the newly developed Au@PPyC/SrTiO3 photocatalyst has been tested on insecticide imidacloprid and on methylene blue (MB) dye. The current Au@PPyC/SrTiO3 photocatalytic framework exhibited ultrafast skills by removing 96.65% of imidacloprid just in 15 min and found to be ∼3.5 times more effective than bare SrTiO3. Besides this Au@PPyC/SrTiO3 photocatalyst was proven to be extremely destructive for resistant MB dye structure.

High-pressure syntheses, crystal structures, and magnetic properties of novel quadruple perovskite oxides LaMn3Ru2Mn2O12 and LaMn3Ru2Fe2O12

Quadruple perovskite oxides LaMn3Ru2M2O12 (M = Mn, Fe) have been synthesized under high-pressure and high-temperature conditions of 8 GPa and 1373 K. Synchrotron X-ray powder diffraction study demonstrates that both oxides crystallized in AA'3B4O12-type cubic quadruple perovskite structures, where the Ru and M ions did not form the special ordering at B-site. X-ray absorption spectroscopy reveals that the valence states are represented as LaMn3+3Ru3+2M3+2O12 (M = Mn, Fe) in the ionic models, indicating that the isovalent states of Ru3+ and M3+ ions disturb the B-site ordering. Magnetization, heat capacity, and neutron diffraction data prove that short-range magnetic orderings are predominant for both compounds instead of long-range magnetic orderings. We conclude that the competition between ferromagnetic and antiferromagnetic superexchange interactions between Ru3+ and M3+ ions at B-site prevent the long-range magnetic ordering Mn3+ ions at A′-site, although the A'- and B-site magnetic sublattices are expected to be intrinsically independent in A′-Mn quadruple perovskite system. This finding represents that the atomic ordering of the B-site is essential for the precise design of magnetic structures for the LaMn3M2M′2O12 quadruple perovskite series.