Wide-angle Powder X-ray Diffraction Research Articles

Efficacy of electrospun PAN/g-C3N4 nanofibers as a photocatalyst for the deterioration of hazardous azo dyes

PAN and PAN/g-C3N4 nanofibers were fabricated using the electrospinning technique. Meanwhile, g-C3N4 nanoflakes were synthesized using the thermal decomposition technique. The challenge of reusing powder catalysts was ultimately surmounted due to the use of dispersed g-C3N4. Characterization of the as-fabricated PAN/g-C3N4 NFs was performed employing wide-angle powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV–Vis spectrophotometry (UV–Vis), thermogravimetry analysis (TGA), N2 adsorption-desorption isotherms (BET) and X-ray photoelectron spectrometer (XPS). According to morphological studies, g-C3N4 nanoflakes get uniformly decorated over PAN fibers with a greater specific surface area and smaller band gap than g-C3N4, exhibiting maximal uniformity in dispersion. Under solar light irradiation, PAN (71%), g-C3N4 (84%), and PAN/g-C3N4 nanofibers (95%) showed excellent photocatalytic performances for the degradation of Methyl orange dye (MO) in 120 min with 95% degradation. Similarly, PAN (61%), g-C3N4 (72%), and PAN/g-C3N4 nanofibers (91%) showed photocatalytic performances for the degradation of Congo red dye (CR) in 160 min with 91% degradation. This effective degradation was due to a shift in band gap with high porosity of PAN/g-C3N4 NFs compared to pure materials such as PAN and g-C3N4.

Chemical reaction driven self-assembly of a nucleobase functionalized molecule

Molecular self-assembly is an important aspect in the nano technology and nano science which is exploited to produce complex supramolecular nanoarchitectures. Different strategies are used to achieve the molecular self-assembly in the laboratory. Here, the methylation reaction is used to induce the supramolecular order in the synthesized guanine functionalized molecules. Methylation is an important biological process which is used for DNA methylation. The methylation reaction driven formation of higher order self-assembly is discussed. The formation of the activated building blocks is studied using high-performance liquid chromatography. The N7 methylation is observed majorly. The pH of the medium is decreased with the progress of the reaction. The progress of self-assembly upon the addition of dimethyl sulphate is monitored by fluorescence, circular dichroism spectroscopy, 1H nuclear magnetic resonance and turbidity experiments. Additionally, Thioflavin T dye binding, wide-angle powder X-ray diffraction, circular dichroism spectroscopy experiments are performed to establish the formation of the chemical reaction driven self-assembled hydrogel. The formation of the nanofiber inside the hydrogel is confirmed by performing various microscopic experiments.

Lysine-based non-cytotoxic ultrashort self-assembling peptides with antimicrobial activity.

Peptide-based molecules and their hydrogels are useful materials for biomedical applications due to the reversible nature of their self-assembly as well as the diversity of nanostructures that can be created starting from low-molecular weight compounds. In this study, we have focused on comprehending the characteristics of fibrillar networks of l-lysine-based self-assembled dipeptide hydrogels with a focus on their antibacterial properties. For that purpose, l-lysine has been complemented with hydrophobic aromatic moieties coming from l-phenylalanine and benzyloxyxarbonyl N-capping. In addition, the peptide C-terminus is blocked with alkylamides of different chain lengths which introduces additional dispersive interactions and hydrophobicity. These materials were well characterized by transmission electron microscopy, scanning electron microscopy, wide-angle powder X-ray diffraction and oscillatory rheology. Finally, biocompatibility and antimicrobial tests were performed showing that these hydrogels are compatible with HEK 293 cells and present a remarkable antibacterial activity against both Gram positive (S. aureus) and Gram negative (E. coli) bacteria.

Investigation of the Photocatalytic Activity of Electrospun and Surface-Modified PAN/α-FeOOH Nanofibers for the Degradation of Hazardous Azo Dyes.

Decoration of α-FeOOH nanorods over PAN nanofibers was performed using the electrospinning technique. The as-designed decorated nanofibers were characterized using various techniques such as wide-angle powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) spectroscopy, UV-vis spectrophotometry (UV-vis), thermogravimetry analysis (TGA), N2 adsorption-desorption isotherm (BET), and X-ray photoelectron spectrometry (XPS). α-FeOOH NRs were decorated uniformly over PAN fibers, as observed from its morphological investigation, which shows novelty. 1D α-FeOOH nanorods with PAN nanofibers have not been studied for photocatalytic characteristics. No literature mentions that α-FeOOH nanorods coated in PAN NFs act as photocatalysts to degrade hazardous azo dyes. α-FeOOH nanorods on PAN NFs inhibit aggregation and increase dye binding, boosting photocatalytic performance. PAN/α-FeOOH NFs have a maximal specific surface area with a reduced bandgap than α-FeOOH NRs. PAN/α-FeOOH nanofibers showed excellent photocatalytic activity for the degradation of Trypan blue (TB) (120 min, 99.7%) and Eriochrome black T (EBT) dyes (160 min, 97.6%), respectively, under solar light irradiation. PAN/α-FeOOH NFs have the potential to be used in the degradation of azo dyes and the treatment of wastewater due to their low energy requirements and versatility.

Histidine-Containing Amphiphilic Peptide-Based Non-Cytotoxic Hydrogelator with Antibacterial Activity and Sustainable Drug Release.

A histidine-based amphiphilic peptide (P) has been found to form an injectable transparent hydrogel in phosphate buffer solution over a pH range from 7.0 to 8.5 with an inherent antibacterial property. It also formed a hydrogel in water at pH = 6.7. The peptide self-assembles into a nanofibrillar network structure which is characterized by high-resolution transmission electron microscopy, field-emission scanning electron microscopy, atomic force microscopy, small-angle X-ray scattering, Fourier-transform infrared spectroscopy, and wide-angle powder X-ray diffraction. The hydrogel exhibits efficient antibacterial activity against both Gram-positive bacteria Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli). The minimum inhibitory concentration of the hydrogel ranges from 20 to 100 μg/mL. The hydrogel is capable of encapsulation of the drugs naproxen (a non-steroidal anti-inflammatory drug), amoxicillin (an antibiotic), and doxorubicin, (an anticancer drug), but, selectively and sustainably, the gel releases naproxen, 84% being released in 84 h and amoxicillin was released more or less in same manner with that of the naproxen. The hydrogel is biocompatible with HEK 293T cells as well as NIH (mouse fibroblast cell line) cells and thus has potential as a potent antibacterial and drug releasing agent. Another remarkable feature of this hydrogel is its magnification property like a convex lens.

One-pot synthesis of iron oxide - Gamma irradiated chitosan modified SBA-15 mesoporous silica for effective methylene blue dye removal

The development of adsorption technology and the processing of radiation have both been influenced by chitosan adsorbent (γ-chitosan), a raw material with unique features. The goal of the current work was to improve the synthesis of Fe-SBA-15 utilizing chitosan that has undergone gamma radiation (Fe-γ–CS–SBA-15) in order to investigate the removal of methylene blue dye in a single hydrothermal procedure. High-resolution transmission electron microscopy (HRTEM), High angle annular dark field scanning transmission electron microscopy (HAADF-STEM), small- and wide-angle X-ray powder diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR) and Energydispersive X-ray spectroscopy (EDS) were used to characterize γ–CS–SBA-15 that had been exposed to Fe. By using N2-physisorption (BET, BJH), the structure of Fe-γ–CS–SBA-15 was investigated. The study parameters also included the effect of solution pH, adsorbent dose and contact time on the methylene blue adsorption. The elimination efficiency of the methylene blue dye was compiled using a UV-VIS spectrophotometer. The results of the characterization show that the Fe-γ–CS–SBA-15 has a substantial pore volume of 504 m2 g−1 and a surface area of 0.88 cm3 g−1. Furthermore, the maximum adsorption capacity (Qmax) of the methylene blue is 176.70 mg/g. The γ-CS can make SBA-15 operate better. It proves that the distribution of Fe and chitosan (the C and N components) in SBA-15 channels is uniform.

The Structure of Ordered Mesoporous Materials Synthesized from Aluminum Phyllosilicate Clay (Bentonite).

This paper reports the synthesis and structural analysis of mesoporous silica materials with the use of aluminum phyllosilicate clay (bentonite) as an alternative silica source. In the proposed synthesis, bentonite, as natural aluminosilicate, was used instead of commercially available and quite expensive tetraethyl orthosilicate (TEOS) silica source. The objective of the research study was to determine the effect of aluminum loading in the mesoporous silica body for ordering structure, porosity, and potential sorption capacity to thorium ions. The unique direction developed in this procedure is focused on preparing advanced materials from natural sources with their own desired functionality and general availability. The applied procedure based on the classic, one-step synthesis of SBA-15 silicates was modified by gradually increasing the bentonite amount with simultaneous reduction of the TEOS content. The structural and morphological characterization, as well as evaluation of the porous structure of the obtained materials, was performed using powder wide-angle X-ray diffraction (XRD), small-angle scattering (SAXS), transmission and scanning electron microscopy (TEM, SEM), low-temperature nitrogen adsorption-desorption methods and potentiometric titration. The new, cost-effective composites for the removal of Th(IV) ions are proposed. The synergistic effect of expanding the porous surface using bentonite as a silica precursor and the presence of thorium-binding groups (such as Al2O3) is indicated.

Stepwise pesudopolyrotaxane nanostructure formation from supramolecular self-assembly by inclusion complexation of fast violet B with α- and β-cyclodextrins

The current work deals with fast violet B (FVB) and cyclodextrins (α-CD and β-CD) inclusion complex into pesudopolyrotaxane nanorod by supramolecular self-assembly. FVB/α-CD forms 2:2 from 1:1 and FVB/β-CD forms 1:2 from 1:1 inclusion complexes, which further self assembled to form nanorod and nano cluster structures. The nanorods formed through step-by-step process after FVB encapsulation into cyclodextrins nano cavities. Wide angle powder X-ray diffraction exposed the crystallinity of the materials, thermal analysis, Fourier Transform Infrared Spectroscopy (FTIR) and Proton Nuclear Magnetic Resonance spectroscopy (1H NMR and 2D ROESY) confirmed FVB encapsulation into the CDs cavities. Amido functionality of FVB molecule is twisted when it is encapsulated within α-CD and β-CD cavities. Computational studies further divulge that the complex formation is an enthalpy-entropy driven process.

Poly(L-glutamic acid) via catalytical hydrogenation for the fabrication of carbon nanotube nanocomposites

Abstract The synthesis of poly(L-glutamic acid) (PG) was investigated. Reduction of poly(benzyl-L-glutamate) by the palladium/charcoal catalyst proved to be an effective method for obtaining polyglutamic acid pure and particularly exhibiting in the α-helix secondary structure. The structure of this synthetic polypeptide was assessed by infrared spectroscopy, gel permeation chromatography, proton nuclear magnetic resonance spectroscopy, temperature-modulated differential scanning calorimetry and wide-angle powder X-ray diffraction methods. The α-helical PG was, for the first time, combined with multi-walled carbon nanotubes (MWCNTs). The obtained PG was demonstrated to be a promising matrix to disperse MWCNTs, forming MWCNT/PG biocomposites.

Enabling Oxygen-Sulfur Exchange Reaction to Produce Semicrystalline Copolymers from Carbon Disulfide and Ethylene Oxide.

This work describes the first example of semicrystalline poly(thiocarbonate)s from carbon disulfide (CS2 ) and ethylene oxide (EO), two mass producible low-cost monomers. Lewis acid/base pairs (LPs) exhibit high activity (EO conversion up to >99%, 8h) in catalyzing the copolymerization under low Lewis pair/monomer ratio of 1:1500. Oxygen-sulfur exchange reaction (O-S ER) during the copolymerization of CS2 and EO, the generation and mutual copolymerization with COS, CO2 , and episulfide, is harnessed to introduce crystallizable segments [SC(O)O and SC(S)S] in the copolymer. The type of Lewis base is found to have a great impact on the chain microstructure and the crystalline properties. The formed copolymers with melting point from 117.7 to 245.3°C are obtained. The maximum crystallinity is estimated to be 78% based on the powder wide-angle X-ray diffraction pattern. This work provides a general method to prepare semicrystalline sulfur-containing polymers.

Magnetic methylene-based mesoporous organosilica composite-supported IL/Pd: a powerful and highly recoverable catalyst for oxidative coupling of phenols and naphthols

A novel magnetic methylene-based mesoporous organosilica composite-supported IL/Pd complex (Fe3O4@MePMO-IL/Pd) was synthesized and characterized, and its catalytic performance was investigated. The preparation of the Fe3O4@MePMO composite was achieved through coating of Fe3O4 nanoparticles with a mixture of tetramethoxysilane, bis(triethoxysilyl)methane, and (3-chloropropyl)-trimethoxysilane in the presence of cetyltrimethylammonium bromide surfactant. The Fe3O4@MePMO was then modified with alkyl imidazolium ionic liquid and palladium species to deliver the Fe3O4@MePMO-IL/Pd nanocatalyst. This catalyst was characterized using Fourier transform infrared, thermal gravimetric, wide-angle powder X-ray diffraction, low-angle powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer, energy-dispersive X-ray, and nitrogen adsorption–desorption analyses. The Fe3O4@MePMO-IL/Pd was effectively used as a highly recoverable and durable catalyst for the selective oxidative coupling of phenols and 2-naphthols under aerobic conditions.

Nanofibrils of a CuII-Thiophenyltriazine-Based Porous Polymer: A Diverse Heterogeneous Nanocatalyst

Herein, we report knitting of a thiophenyltriazine-based porous organic polymer (TTPOP) with high surface area and high abundance of nitrogen and sulfur sites, synthesized through a simple one-step Friedel–Crafts reaction of 2,4,6-tri(thiophen-2-yl)-1,3,5-triazine and formaldehyde dimethyl acetal in the presence of anhydrous FeCl3, and thereafter grafting of Cu(OAc)2·H2O in the porous polymer framework to achieve the potential catalyst (CuII-TTPOP). TTPOP and CuII-TTPOP were characterized thoroughly utilizing solid-state 13C-CP MAS NMR, Fourier transform infrared, wide-angle powder X-ray diffraction, thermogravimetric analysis, and X-ray photoelectron spectroscopy and surface imaging by transmission electron microscopy and field emission scanning electron microscopy. The porosity of the nanomaterials was observed in the surface imaging and verified through conducting N2 gas adsorption techniques. Keeping in mind the tremendous importance of C-C and C-N coupling and cyclization processes, the newly synthesized CuII-TTPOP was employed successfully for a wide range of organic catalytic transformations under mild conditions to afford directly valuable diindolylmethanes and spiro-analogues, phthalimidines, propargyl amines, and their sugar-based chiral compounds with high yields using readily available substrates. The highly stable new heterogeneous catalyst showed outstanding sustainability, robustness, simple separation, and recyclability.

Molecular aggregation structure and water repellency of Poly(perfluorohexyl acrylate) with a carbamate linkage

Liquid repellency of comb-shaped polyacrylates with perfluoroalkyl side-chains associates with the ordered structure of the side-chains at the surface. The molecular aggregation structure and surface properties of poly{2-[(perfluorohexylethyl)carbamate]ethyl}acrylate (PFAUr-C6) were studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), powder wide-angle X-ray diffraction (WAXD), grazing incidence wide-angle X-ray diffraction (GI-WAXD), temperature-controlled Fourier transform infrared spectroscopy (FTIR), contact angle measurements, and X-ray photoelectron spectroscopy (XPS). Poly[2-(perfluorohexyl)ethyl]acrylate (PFA-C6) was compared with PFAUr-C6 to verify the effect of carbamate linkage on the aggregation structure and surface properties. The perfluorohexyl groups in PFAUr-C6 produced a double-layered smectic structure, whereas the perfluorohexyl groups in PFA-C6 showed no ordered structure. The double-layered smectic structure in PFAUr-C6 was induced by the hydrogen bonding interaction in the carbamate linkers. PFAUr-C6 showed poor water repellency similar to PFA-C6 because of the rapid surface rearrangement. Although the perfluorohexyl groups produced smectic order structure at the film surface, the lack of positional order in the smectic layers and the low ordered structure content allowed the surface rearrangement.

Dimethylamine substituted bisbenzocoumarin amides with solvatochromic and mechanochromic properties

Stimuli responsive luminescent materials have attracted increasing attention for their potential application in many fields. In this work, dimethylamine substituted bisbenzocoumarins amides (DBCE and DBCP) are synthesized and their optical properties are investigated. These molecules show solvatochromic properties. The orange fluorescence emission of DBCE in crystalline state is blue-shifted to yellow emission upon grinding. The orange color could be recovered by recrystallization process. Powder wide-angle X-ray diffraction and DSC experiments reveal that the transformation from crystalline states to amorphous states under external stimuli is responsible for the mechanochromic properties. This work developed a new kind of binaphthane-type luminescent materials with blue-shifted mechanochromic properties.

High performance visible light photocatalysis of electrospun PAN/ZnO hybrid nanofibers

ZnO nanorods (NRs) immobilized PAN nanofibers were prepared using electrospinning technique. ZnO were dispersed uniformly, which helps to overcome the difficult recycling of powder catalyst. The as-obtained fibers were characterized with wide-angle powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectrophotometry (UV-vis-DRS), Thermogravimetry analysis (TGA), N2 adsorption–desorption isotherms (BET), and X-ray photoelectron spectrometer (XPS). The morphological studies revealed that ZnO NRs were aligned parallel to the axis of fibers. PAN/ZnO hybrid NFs shows better regularity and uniformity in diameter (˜800 nm) with large specific surface area and smaller energy band gap comparted to ZnO NRs. Under visible light irradiation, PAN/ZnO hybrid nanofibers have had excellent photocatalytic performances for the degradation of cationic MG dye (200 min, 99%) and anionic MO dye (280 min, 99%) respectively. Due to the electrostatic attraction between cationic dye and anionic PAN/ZnO, the degradation rate towards MG dye was higher than MO dye. Recyclability study shows that after fifth cycle, 93% efficiency was observed.

Synthesis and Characterization of Syndiotactic Polystyrene-Polyethylene Block Copolymer.

The direct synthesis of syndiotactic polystyrene-block-polyethylene copolymer (sPS-b-PE) with a diblock structure has been achieved. The synthetic strategy consists of the sequential stereocontrolled polymerization of styrene and ethylene in the presence of a single catalytic system: cyclopentadienyltitanium(IV) trichloride activated by modified methylaluminoxane (CpTiCl3/MMAO). The reaction conditions suitable for affording the partially living polymerization of these monomers were identified, and the resulting copolymer, purified from contaminant homopolymers, was fully characterized. Gel permeation chromatography coupled with two-dimensional NMR spectroscopy COSY, HSQC, and DOSY confirmed the block nature of the obtained polymer, whose thermal behaviour and thin film morphology were also investigated by differential scanning calorimetry, powder wide angle x-ray diffraction, and atomic force microscopy.

Microwave solvothermal carboxymethyl chitosan templated synthesis of TiO2/ZrO2 composites toward enhanced photocatalytic degradation of Rhodamine B

A series of TiO2/ZrO2 composites with various molar ratios of ZrO2:TiO2 were synthesized by a facile and mild microwave hydrothermal method with carboxymethyl chitosan (CMCS) as templates. The as-obtained products were characterized with wide-angle powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV–vis diffuse reflectance spectrophotometry (UV–vis-DRS), N2 adsorption-desorption isotherms (BET), and X-ray photoelectron spectrometer (XPS). The TiO2/ZrO2 composites with heterogeneous structure consisted of particles which showed a better regularity and uniform with about 800 nm in diameter, and showed a larger specific surface area and smaller energy band gap than pure ZrO2. Comparative experiments including varying the pH of the solution and the content of titania demonstrated that the 5% TiO2/ZrO2 composites (nTi:nZr = 5:100) at pH = 10.3 possessed the best photocatalytic property. Moreover, the possible reasons for these phenomena were clarified. Cyclic experiments proved that the resulting TiO2/ZrO2 composites as photocatalyst could be reused efficiently. Meanwhile, a possible mechanism of photocatalysis was proposed.

Multi-responsive red solid emitter: Detection of trace water and sense of relative humidity

A multi-responsive D-A type compound ( CYQ ) based on pyrone and triphenylamine was designed and successfully synthesized. The target compound exhibited distinct aggregation-enhanced emission (AEE) effect. Solvatochromic experiment and density functional theory (DFT) indicated CYQ possessed excellent intramolecular charge transfer (ICT) ability. Besides, its mechanofluorochromic property (MFC) was found with a 37 nm red-shift. Powder wide-angle X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) measurements were performed to demonstrate the transformation from the crystalline to amorphous states upon grinding. Surprisingly, CYQ displayed a hypersensitive response to trace water in organic solvents with an excellent detection limit as low as 0.0096% in tetrahydrofuran (THF). Furthermore, it was found that the fluorescent intensity of CYQ declined progressively upon humidity rise, and its color change can be witnessed by naked eyes. Therefore, the relative humidity (RH) sensing strategy guarantees the AIEgen to become a colorimetric sensor under various conditions.

Amino-Acid-Based Metallo-Hydrogel That Acts Like an Esterase.

A histidine-based amphiphile containing a C14 fatty acyl chain, N- histidyl N'-myristry ethyl amine (AM1, 14.7 mM) forms hydrogels in the presence of Fe3+ (within the range 1.47 to 4.41 mM) and Hg2+ (within the range 3.67 to 11.02 mM) ions in aqueous dispersions at pH 6.6 (27 °C). The imidazole ring of the histidine residue plays a vital role to interact with these metal-ions. The thermal and mechanical stability of these metallo-hydrogels can be tuned by changing the proportion of amphiphile to metal ion ratio (1:0.1 to 1:0.3 for Fe3+-containing gel and 1:0.25 to 1:0.75 for Hg2+-containing gel). The metallo-hydrogels were characterized by different spectroscopic and microscopic techniques, low- and wide-angle powder X-ray diffraction, and small-angle X-ray scattering studies. FT-IR and NMR spectroscopic studies indicate the participation of the imidazole ring in metal-ion binding. Low- and wide-angle powder X-ray diffraction and small-angle X-ray scattering data are in favor of a layered structure of the supramolecular assembly of the AM1 in the presence of metal-ions. Both, the amphiphiles and the metal ion induced hydrogels reveal catalytic activity of p-nitrophenyl esters hydrolysis for the acetyl, n-butyl and n-octyl esters . Ferric ion containing metallo-hydrogel exhibits higher catalytic activity than the corresponding AM1 aggregate in the absence of metal ions.

Mesoporous CdS via Network of Self-Assembled Nanocrystals: Synthesis, Characterization and Enhanced Photoconducting Property.

Semiconduction nanoparticles are intensively studied due to their huge potential in optoelctronic applications. Here we report an efficient chemical route for hydrothermal synthesis of aggregated mesoporous cadmium sulfide (CdS) nanoparticles using supramolecular-assembly of ionic and water soluble sodium salicylate as the capping agent. The nanostructure, mesophase, optical property and photoconductivity of these mesoporous CdS materials have been characterized by using small and wide angle powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2-sorption, Raman analysis, Fourier transformed infrared (FT-IR), UV-Visible DSR spectroscopy, and photoconductivity measurement. Wide angle XRD pattern and high resolution TEM image analysis suggested that the particle size of the materials is within 10 nm and the nanoparticles are in well-crystallized cubic phase. Mesoporous CdS nanoparticles showed drastically enhanced photoelectrochemical response under visible light irradiation on entrapping a photosensitizer (dye) molecule in the interparticle spaces. Efficient synthesis strategy and the enhanced photo response in the mesoporous CdS material could facilitate the designing of other porous semiconductor oxide/sulfide and their applications in photon-to-electron conversion processes.