Optimal Synthetic Conditions Research Articles

Advancements in polyol synthesis: expanding chemical horizons and Néel temperature tuning of CoO nanoparticles

The polyol synthesis of CoO nanoparticles (NPs) is typically conducted by dissolving and heating cobalt acetate tetrahydrate and water in diethylene glycol (DEG). This process yields aggregates of approximately 100 nm made of partially aligned primary crystals. However, the synthesis demands careful temperature control to allow the nucleation of CoO while simultaneously preventing reduction, caused by the activity of DEG. This restriction hinders the flexibility to freely adjust synthesis conditions, impeding the ability to obtain particles with varied morpho-structural properties, which, in turn, directly impact chemical and physical attributes. In this context, the growth of CoO NPs in polyol was studied focusing on the effect of the polyol chain length and the synthesis temperature at two different water/cations ratios. During this investigation, we found that longer polyol chains remove the previous limits of the method, allowing the tuning of aggregate size (20–150 nm), shape (spherical-octahedral), and crystalline length (8–35 nm). Regarding the characterization, our focus revolved around investigating the magnetic properties inherent in the synthesized products. From this point of view, two pivotal findings emerged. Firstly, we identified small quantities of a layered hydroxide ferromagnetic intermediate, which acted as interference in our measurements. This intermediate exhibited magnetic properties consistent with features observed in other publications on CoO produced in systems compatible with the intermediate formation. Optimal synthetic conditions that prevent the impurity from forming were found. This resolution clarifies several ambiguities existing in literature about CoO low-temperature magnetic behavior. Secondly, a regular relationship of the NPs' TN with their crystallite size was found, allowing us to regulate TN over ~ 80 K. For the first time, a branching was found in this structure-dependent magnetic feature, with samples of spheroidal morphology consistently having lower magnetic temperatures, when compared to samples with faceted/octahedral shape, providing compelling evidence for a novel physical parameter influencing the TN of a material. These two findings contribute to the understanding of the fundamental properties of CoO and antiferromagnetic materials.

Synthesizing Ordered Network Structures Using Linear Polymers: A Study on Optimal Synthetic Conditions

Synthesizing Ordered Network Structures Using Linear Polymers: A Study on Optimal Synthetic Conditions

A step forward towards optimized iron–nickel bimetal oxide core–shell nanoparticles and their magnetic properties

The core–shell nanoparticles of Fe3O4 and NiO are synthesized under different reaction conditions and are characterized by UV–vis and fluorescence spectroscopy, DLS, SEM, EDX, XRD, VSM, and FTIR spectroscopy. These techniques evaluated optimal synthetic conditions for desired size, morphology, stability, and crystallinity of these core–shell nanoparticles. Increasing the concentration of salt for shell material (Fe3O4 or NiO) in core–shell NPs resulted in better coating and increase in hydrodynamic size from 227 nm to 531 nm for (Fe3O4)NiO, and 244 nm to 544 nm for (NiO)Fe3O4, whereas lower concentration and higher temperature (80 °C) for (Fe3O4)NiO and lower temperature (25 °C) for (NiO)Fe3O4, higher pH 13 and 11 for (Fe3O4)NiO and (NiO)Fe3O4 respectively, and fast (quick) addition of reactants produces homogenous small sized nanoparticles. Stability is generally attained at higher concentration, higher temperature (80 °C), higher pH (13 and 11 for (Fe3O4)NiO and (NiO)Fe3O4 respectively), and slow addition (10 min) of reactants. Fluorescence enhancement is observed for (Fe3O4)NiO core–shell NPs at high concentration, temperature, pH and slow addition of reactants, representing proper coating of NiO. For (NiO)Fe3O4 NPs, fluorescence quenching is observed at higher concentration, lower temperature, higher pH, and slow addition of reactants representing proper coating of Fe3O4. XRD depicted pure cubic crystalline nature of these core–shell nanoparticles without any impurity. The identified optimized conditions are useful for obtaining nanoparticles with desired properties for various applications including sensing and catalysis etc. Magnetic properties of pure and core–shell nanoparticles show ferrimagnetic behavior for Fe3O4 NPs and weak ferromagnetic or superparamagnetic behavior NiO NPs.

A multiparametric study for size and stability of hybrid Fe 2 O 3 -NiO nanoparticles and their statistical transformation

A multiparametric study for size and stability of hybrid Fe ₂ O ₃ -NiO nanoparticles and their statistical transformation

Thermo-thickening/amphoteric polymer nanocomposite incorporating vinyl-functionalized nano-silica as a viscosifier for high-salt and ultra-high temperature water-based drilling fluids

In the relentless extraction of oil and gas from deeper reservoirs, the harsh geological conditions pose significant rheological challenges for conventional polymer viscosifiers. Hence, the spotlight has turned to the unique potential of thermo-thickening polymers to enhance drilling fluid performance. In this study, a novel polymer nanocomposite (VMS-ATA) was designed to associate thermo-thickening responses, amphoteric characteristics, and vinyl-functionalized nano-silica (VMS) as nanofillers for the formation of a thermally stable polymer nanocomposite-bentonite hybrid system. VMS-ATA was prepared via in-situ polymerization under optimal synthetic conditions, and the unique chemical structure was analyzed using various techniques such as Fourier transform spectroscopy, proton nuclear magnetic resonance, elemental analysis, thermogravimetric analysis, X-ray spectroscopy, transmission electron microscopy, and scanning electron microscopy. The study systematically investigated the enhancement of in-situ covalent bonding characteristics of VMS on the thermo-thickening behavior of VMS-ATA, while comparing it with amine-nano-silica (AMS) incorporated in a polymer composite (AMS-CGBA). TGA analysis revealed that VMS-ATA exhibits excellent thermal stability compared to AMS-CGBA, attributed to the thermally stable VMS (370 °C) compared to AMS (355 °C). Interestingly, VMS-ATA displayed relatively stable and prolonged thermo-thickening responses (100–200 °C) owed to high thermal-induced activation responses above the lower critical solution temperature (LCST) in both salt-free and saturated salt contamination. The rheological results of VMS-ATA viscosity retention at 220 °C and 20 wt% NaCl, exceeded 60 %, which is twice that of AMS-CGBA-containing fluids. As demonstrated, VMS-ATA and AMS-CGBA exhibited similar macro-interactions with rigid imidazole and caprolactam rings, but significantly differed in their micro-interactions owed to in-situ covalent binding induced by VMS compared to hydrogen bonding in AMS. This breakthrough exhibited the potential of VMS nanofillers to effectively maintain thickening response by facilitating efficient heat distribution to minimize rapid viscosity decay and revolutionize the landscape of high-salt and high-temperature (HSHT) drilling applications.

Surface N Sites Mediate the Formation of Li Metal Cluster@N-Enriched Hierarchically Porous Carbon for Ultrahigh-Capacity Lithium Storage.

Graphite is the popular anode material of current lithium-ion batteries (LIBs). However, its low specific capacity and poor lithium intercalation potential hinder its use for high-power and large-scale energy storage. To meet the demand for energy storage, novel anode materials with high capacity, fast chargeable capability, and long cycle life are of great interest. Herein, we demonstrate an advanced nitrogen-enriched hierarchical porous carbon serving as a lithiophilic anode material for ultrahigh capacity and long-life LIBs. NHPC-700 (under optimal synthetic conditions), featuring a high surface area, rich N-doping, high porosity, and partially graphitized nanosheet structures, is successfully fabricated from a Schiff-base copolymer via a template-incipient wetness impregnation method. NHPC-700 exhibits an ultrahigh reversible lithium storage capacity of 2796 mA h g-1 at 0.1 A g-1 while still maintaining a high capacity of 526 mA h g-1 at 10 A g-1 after 1000 cycles. Theoretical and experimental studies reveal that this remarkable Li storage performance can be attributed to the large number of N lithiophilic sites on the inner surface of the small mesoporous pores. These sites guide Li metal nucleation in the initial period and control well the volume variation during charge/discharge cycles, thus exhibiting excellent cycle stability and great potential for practical application.

Insight biological prospects of silver@graphene oxide nanocomposite synthesized by Muntingia calabura leaf extract: Stunning ROS-related antibacterial mechanism under visible light

In this study, silver@graphene oxide (Ag@GO) nanocomposite was synthesized using Muntingia calabura leaf extract with temperature controlled at normal conditions. It was accounted that the optimal synthetic conditions were recorded at 0.9 mL AgNO3 (5 mg/mL) solution, GO:AgNO3 = 1:1 (v/v), and reaction time of 20 min, as a witness of the uniform distribution of AgNPs on the GO sheets with the average size of 17.79 ± 3.95 nm. Afterward, the bioactivities of the Ag@GO were determined via the assays of antioxidant, anti-inflammatory, antifungal, antibacterial, and cytotoxicity performances. Along with this, the antibacterial mechanism was also examined through the addition of various scavengers into the Ag@GO suspension at visible illumination. As a result, the Ag@GO exhibited outstanding biological inhibition in all experiments in comparison with individual precursors of the extract, AgNPs, and GO. Interestingly, regarding the bacteriostatic effects of the Ag@GO on Pseudomonas aeruginosa and Staphylococcus aureus, the Ag@GO performed the highest antibacterial efficiency, especially under the photo-excitation of visible-light irradiation. As well, the generation of various radicals, namely hydroxyl (•OH), hydroperoxyl (•OOH), and superoxide (• O2−), as well as the non-radical hydrogen peroxide (H2O2) evidently promotes the bactericidal inhibition of the Ag@GO. Furthermore, the stability of the Ag@GO after three months of storage under the suspension system and with the foregoing results declared the prospects in biomedicine of nanomaterials from the green synthesis approach.

Fe-N-C Catalysts Synthesized on Conductive Non-Carbon Support Materials for Improved PEMFC Durability

Global energy demand will be continuously rising in the foreseeable future. To mitigate the results of climate change it is necessary to reduce the emittance of green house gasses. One very promising approach is to switch to hydrogen as energy carrier and use proton membrane fuel cells (PEMFCs) as the primary energy generation technology. Here, hydrogen and oxygen/air are used to directly generate electrical energy with only water as byproduct. Both reactions need to happen efficiently at the same time. The oxygen reduction reaction (ORR), however, is a very sluggish four-electron-reaction and needs efficient catalysts.The state-of-the-art catalyst is platinum but that is a very scarce and expensive metal. Hence, it is important to switch to precious-metal-group (PGM) free catalysts. In recent years, bio inspired iron-based Fe-N-C catalysts have been shown to approach ORR activities that are competitive with those of platinum, even though they need a higher catalyst loading than Pt to reach the desired current densities.1-3 Those catalysts feature single Fe atoms surrounded by four N atoms in graphitic carbon. The drawback of those materials is their lower stability compared to PGM materials. In a nutshell, the carbon matrix oxidizes during operation in PEMFCs, changing the morphology of the catalytic center and rendering it less active, or inactive, depending on the carbon oxidation extent. Demetallation phenomena are also possible, leaving a N4 cavity without metal cation center. It was shown recently by Wu et al.4 that it is possible to raise durability by adding an additional carbon layer on the catalyst. One alternative approach to reduce those degradations is to interface Fe-N4 sites with a carbon-free support. The targeted support material must be immune to corrosion in acid and withstand the typical ORR electrochemical potentials. It also has to be electrically conductive to facilitate electron transfers, both locally and on long scale.In this work, conductive ceramic metal oxide materials were investigated as possible alternative catalyst supports. Those materials are resistant to acid and can withstand prolonged potentials at operating conditions in PEMFCs. The conductivity is usually raised by doping, since many of those ceramics are semi-conductors. However, during the synthesis of the Fe-N-C catalysts, high temperatures are generally applied. Such treatments can be detrimental to the conductivity of the ceramics due to metal aggregation (in case of doped materials) and may also lead to morphological changes. A robust method to synthesize Fe-N-C catalysts is by mixing the separate Fe, N and C precursors and using optimized thermal treatment at high temperatures. They can be further pyrolyzed with ammonia to introduce defects and basicity into the structure, which leads to higher catalytic activity but even lower stability in acid medium. In this study, the effect of the pyrolysis conditions on conductive oxide materials was investigated with various characterization methods, e.g. x-ray diffraction, scanning electron microscopy and N2 sorption isotherms. This gives insights into the changes that happen during the thermal treatment and can be used to find optimal synthetic conditions to keep most desired parameters of the ceramics preserved or only minimally lowered. Several different approaches were used to combine Fe-N-C catalysts with conductive ceramic metal oxide materials. The resulting materials were characterized and tested with rotating disc electrode techniques and in PEM fuel cells for their ORR-activity and durability.(1) F. Jaouen et al., Nature Catalysis, 2022, 5, 311–323(2) H. A. Gasteiger et al., Science, 2009, 324, 48−49(3) L. Elbaz et al., ACS Applied Energy Materials 2022, 5 (7), 7997-8003(4) G. Wu et al., Nature Energy, 2022, 7, 652–663

Radiation synthesis and chemical modifications of p(AAm-co-AAc) hydrogel for improving their adsorptive removal of metal ions from polluted water

The research focuses on utilizing gamma irradiation to synthesize polyacrylic acid-co-polyacrylamide p(AAm-co-AAc) hydrogels. The effect of synthetic parameters on physicochemical features of p(AAm-co-AAc) hydrogls were examined, including acrylic acid (AAc): acrylamide (AAm) weight ratios, monomer concentration, and gamma irradiation dosage (kGy). At the optimum synthetic conditions (30 kGy and 75% AAc), different chemical modifications are explored to incorporate sulfonate, hydroxyl, carboxyl, cysteine, thiol, and amine functional groups within the bare hydrogel (Cpd 0) structure. Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses confirmed the success development of functionalized hydrogels (namely Cpd 1 to 6) with three-dimensional porous structures. These modified hydrogels include Cpd 1, a sulfonated hydrogel through a sulfonation reaction; Cpd 2, modified via NaOH hydrolysis; Cpd 3, modified using thionyl chloride; Cpd 4, incorporating cysteine modification through reaction with cysteine; Cpd 5, with 4-(Dimethylamino) benzaldehyde; and Cpd 6, modified with 3,4-Dimethylbenzoic acid.The effect of hydrogel composition and surface functionalities on the swelling capacity and interactions with scale-forming/heavy metal ions (e.g., Ba2+, Sr2+, and Cu2+) was investigated in saline water solution (NaCl = 1000 mg/L). Batch adsorption studies reveal that all modified hydrogels exhibited higher removal efficiency for the three metal ions than unmodified p(AAm-co-AAc) hydrogel, validating the key role of surface functionalities in tailoring hydrogel affinity for metal ions adsorption. Amongst these, NaOH-treated hydrogel (Cpd 2) outperformed all other modified ones in the removal of Cu2+, Ba2+, and Sr2+ ions, with maximum capacities of 13.67, 36.4, and 27.31 mg/g, respectively. Based on adsorption isotherm and kinetic modeling, the adsorption process of the three metal ions onto all modified hydrogels better obeyed Freundlich isotherm and pseudo-first-order kinetic models. Thermodynamic studies also indicated that the adsorption behavior of Sr2+ ions can exhibit both exothermic and endothermic characteristics, depending on the nature of hydrogel surface chemistry. Conversely, the adsorption process of Cu2+ and Ba2+ ions onto all modified hydrogels is endothermic, suggesting favorable chemical adsorption mechanisms. These findings reveal that the specific adsorption performance of hydrogel is dependent on the type of modification and the targeted heavy metal ions. Based on the nature of hydrogel surface functionality, surface modifications can change the charge density, hydrophilicity, and overall chemical environment of the hydrogel, offering a versatile approach to optimize the adsorption affinity/selectivity of hydrogel's in removing scale-forming/heavy metals from water solutions.

Synthesis and design of NaNi1/3Fe1/3Mn1/3O2 cathode materials for long-life sodium-ion batteries

To enable the widespread adoption of residential energy storage, sustainable, low-cost, long-life, and energy-dense battery technologies are required. Sodium-ion offers many of these characteristics, however often the system is tailored for energy rather than cycle life. In this work, the effect of synthesis conditions upon the primary and agglomerated secondary particle size and shape of the sodium-ion cathode material NaNi1/3Fe1/3Mn1/3O2 was investigated for optimization of energy and cycle life. A two-level full factorial experimental design was utilized to examine how the synthesis parameters (pH, molar ratio of ammonia/metal precursor salt, and stirring speed) affect the physical and electrochemical properties. This approach enabled a comprehensive investigation of the main effects and interactions of these parameters. The data from multiple synthesis runs were analyzed using statistical methods and regression analysis. This experimental design provided valuable insights into the relationship between synthesis parameters and material properties. Statistical analysis indicates that both physical and electrochemical properties are mainly controlled through pH and NH4OH, while the effects of stirring speed are less pronounced. The optimal synthetic conditions producing the highest cycling performance were extrapolated from the statistical analysis. A validation experiment showed that particles synthesized with optimum parameters displayed a threefold increase in cycling performance together with uniformly distributed particle size and a high tap density.

Green synthesis of gold nanoparticles using Andrographis paniculata leave extract for lead ion detection, degradation of dyes, and bioactivities

In this study, gold nanoparticles (AuNPs) were synthesized through a facile and environmental-friendly procedure using the aqueous extract of Andrographis paniculata (A. paniculata) as an effective stabilizer and reducing agent. The investigation of the optimal synthetic conditions for AuNPs was achieved at 1.5 mL of the extract, 0.5 mM of HAuCl4, 60 °C, 30 min of reaction time, and pH 6. Simultaneously, the characterization of the produced AuNPs was also thoroughly conducted via various analysis methods, showing that AuNPs were spherical in shape and uniformly distributed with an average particle size of 10 – 15 nm. Moreover, the multi-applications of the material were analyzed regarding the colorimetric detection of heavy metal Pb2+, catalytic elimination for organic dyes, and bioactivities. For the sensing of Pb2+, AuNPs indicated a relatively low detection limit of 12.661 µM and good selectivity in the presence of other metal ions. Meanwhile, the catalytic properties of AuNPs were tested in the reduction of methylene blue, crystal violet, and methylene orange by sodium borohydride, showing excellent degradation efficiencies of over 95%. The bioactivity examinations also confirmed the potential of the extract and AuNPs as effective antibacterial and antioxidant agents. In conclusion, the obtained results suggest the promising applicability of the green-synthesized AuNPs using the A. paniculata extract in various sectors.

Ceramics of the Cs2O–Al2O3 System Prepared by Solid-Phase Technology and the Glycine–Nitrate Combustion Process

Cs2O–Al2O3 ceramic samples containing 20 and 33 mol % cesium oxide were prepared by сeramic technique and by the glycine–nitrate combustion process. The prepared samples were identified and characterized by X-ray powder diffraction and X-ray fluorescence analyses, scanning electron microscopy, and differential thermal analysis. X-ray powder diffraction and scanning electron microscopy showed that the phase composition and surface of the samples change significantly and nonmonotonically depending on the synthetic method used and the heat treatment parameters of the batch. Optimal synthetic conditions and heat treatment parameters for preparing Cs2O–Al2O3 samples were elucidated.

Li-Mn Bimetallic Metal-Organic Framework and Its Derivative as a Cathode for Lithium-Ion Batteries.

The bimetallic organic-inorganic hybrid complex [Li2Mn3(ipa)4(DMF)4]n (ipa = deprotonated 1,3-isophthalic acid, DMF = N,N'-dimethyl formamide) was synthesized via a solvothermal method and then further calcined at high temperature to prepare a spinel-type lithium manganate (LiMn2O4) cathode under different atmospheres with various calcination conditions. The structure of the complex [Li2Mn3(ipa)4(DMF)4]n was represented by single-crystal X-ray diffraction (XRD), powder XRD, and thermogravimetric (TG) analysis. The morphology and elements of LiMn2O4 were analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The electrochemical properties of LiMn2O4 indicated that the direct calcination in an air atmosphere at 850 °C for 12 h was the optimal synthetic condition. The initial discharge specific capacity can reach 95.9 mA h g-1 with an open-circuit voltage of ca. 3.0 V and an upper cutoff voltage of ca. 4.3 V at 0.1 C. The initial discharge-specific capacity of 89.8 mA h g-1 at 1 C had a Coulombic efficiency of 95.3%. This was 73 mA h g-1 at a high rate of 5 C increasing to 91.6 mA h g-1 after returning to 0.1 C. After 500 cycles at 1 C, the system remained at 80.7 mA h g-1 with 89.9% of the initial discharge specific capacity. These features exhibit better stability than that of the reported LiCoO2 and LiNiO2 in battery material for LiMn2O4 enforcement.

Synthesis of α-AlH3 by organic liquid reduction method and its hydrogen desorption performance

Aluminum hydride (AlH3) is considered to be a promising hydrogen storage material due to its moderate dehydrogenation temperature and high hydrogen desorption capacity. However, AlH3 has multiple crystal forms, and it is difficult to prepare a single crystalline, which restricted the development of this material. In this study, a new organic liquid reduction method was used to prepare pure α-AlH3. The synthesis process includes two steps: primary reduction reaction in ether and subsequent desolvation reaction in toluene. The effects of reaction conditions on product composition were discussed in detail. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to characterize the crystal structure and morphology of reaction products. Research results show that the final product is composed of α-AlH3 and γ-AlH3. The composition proportion of α-AlH3/γ-AlH3 can be adjusted by controlling reaction conditions. Through comparison and analysis, an optimal synthetic condition has been gained to obtain pure α-AlH3. The dehydrogenation performance of the obtained pure α-AlH3 were studied through thermal analysis methods. It is found that the α-AlH3 has a hydrogen desorption capacity of about 9.6 wt% below 200 °C. The dehydrogenation activation energy was also evaluated by using Kissinger and Friedman methods. This study provides a more simple and efficient method for synthesising pure α-AlH3, and also offers some reference for the future research of AlH3.

Highly selective lanthanide-doped ion sieves for lithium recovery from aqueous solutions

The increased global demand for lithium is rapidly depleting the lithium ore reserves. Therefore, attention has turned to the recovery of lithium from aqueous solutions, such as lithium-containing brine. Compared with other methods of lithium recovery, adsorption is energy efficient and simple to implement, increasing demand for selective lithium adsorbents. In this study, a selective lithium-ion adsorbent, H4Ti5– xLa xO12, was synthesized via the sol–gel method, followed by heat treatment and acid washing. The effects of the temperature and degree of lanthanum doping ( x) on the crystalline phase, morphology, lithium-ion adsorption capacity, and lithium-ion selectivity of the ion sieve were investigated, and the optimal synthetic conditions were determined. We found that doping with La3+ cations ( x = 0.01) increased the lithium-ion adsorption capacity (23.96 mg g−1 at 25 °C at pH = 12; 8.2% higher than before doping), rate, and selectivity. In addition, the ion sieve could be used over multiple adsorption–desorption cycles with only a minor reduction in the lithium-ion adsorption capacity (22.88 mg g−1). Overall, these results suggest that doping with La3+ cations stabilized the H4Ti5– xLa xO12 crystal structure, alleviated particle agglomeration, expanded the lithium-ion channels, and decreased the resistance to lithium-ion migration, thus improving adsorption performance. The findings suggest that the proposed ion sieve has practical applications in the selective recovery of lithium from aqueous solutions containing a mixture of metal ions.

Response surface methodology optimization and antimicrobial activity of berberine modified trimethoprim carboxymethyl cellulose

Abstract In order to solve the problem of bacterial resistance, increase the antibacterial performance and delay the aging of paper, the berberine modified trimethoprim carboxymethyl cellulose was prepared using trimethoprimethylate carboxymethyl cellulose as raw material and trimethoprimethylate lactate (TMP) as antibacterial modifier by Schiff Base reaction. At the same time, berberine (BBR) was used as graft monomer to prepare a multifunctional protective solution integrating strengthening, antibacterial and good biocompatibility. The optimal process conditions were determined by single factor experiment and response surface method. The structure and properties of the product were characterized by FT-IR, XRD, TG and SEM and the antibacterial properties were evaluated by AGAR disk diffusion method. The results showed that when the mass ratio of dialdehyde carboxymethyl cellulose and modified berberine was 7:15, reaction temperature was 40 °C, and pH was 6.0, the optimum synthetic conditions was obtained. And the minimum inhibitory concentration of the product against Staphylococcus aureus and Escherichia coli were 0.2 mg/mL, minimum diameter of antibacterial zone of 6.7 mm and 7.1 mm, respectively, with good antibacterial effect. This paper lays a foundation for further research on the safe and effective antiquities antibacterial agent, and provides a reference for its further development in paper protection.

Morphology controllable BaNbF5.5(OH)1.5:Mn4+ red phosphor with strong zero phonon line for WLED application

A hydroxy fluoride red phosphor BaNbF5.5(OH)1.5:Mn4+ with dual morphology was designed and manufactured by co-precipitation strategy. The crystal phase structure, controlled morphology and photoluminescence performances were systematically investigated. The Mn4+ non-equivalent doped hydroxy fluoride phosphor has similar luminescence performance to fluoride phosphors, and it is worth noting that it presents a very strong zero phonon line (ZPL) at ∼629 nm at blue light excitation and has high color purity (98.5%). Crystal field intensity (Dq), Racah parameters (B and C) and nephelauxetic effect ratio parameter β1 of the sample were calculated and analyzed, the results indicate that the BaNbF5.5(OH)1.5 matrix provides a strong crystal field environment for Mn4+. The effects of the experimental conditions on the morphology of the phosphors were analyzed, and optimal synthetic conditions were determined. Because of the short fluorescence decay lifetime (τ < 4 ms), this red phosphor may be a prospective red emitting candidate for backlight displays. Moreover, the as-prepared BaNbF5.5(OH)1.5:Mn4+ red phosphor possesses distinguished UV light-induced stability. Thermal stability and hydrophobic stability of the phosphor were analyzed. Thanks to the strong ZPL, WLED device prepared with this phosphor can produce warm white light and show remarkable photoelectric properties, with a color rendering index (CRI, Ra) of up to 92.5 and a correlated color temperature (CCT, Tc) as low as 3944 K. The results indicate that the red phosphor BaNbF5.5(OH)1.5:Mn4+ has application possibilities in WLED illumination and display backlighting.

Tier-grown Expansion of Design-of-Experiments Parameter Spaces for Synthesis of a Nanometer-scale Macrocycle.

A method to find optimum synthetic conditions was devised by combining a data-driven empirical model with a traditional mechanistic model. In this method, an experimental parameter space was empirically obtained by Design-of-Experiments optimizations with machine-learning supplements and was strategically expanded by examination of the mechanistic model of the reaction paths. An extra tier grown on the original 3×3×3 parameter space succeeded in allocating an optimum reaction condition in the expanded 3×3×4 parameter space. The method was specifically devised for the synthesis of a macrocycle, [n]cyclo-meta-phenylenes ([n]CMP), and the largest congener with n=12 was synthesized and fully characterized for the first time. Crystallographic and photophysical analyses revealed favorable features of [12]CMP for the material applications.

Biological activity of silver nanoparticles synthesized with Paenibacillus polymyxa exopolysaccharides

Recently, there has been increased interest in the synthesis of nanoparticles by using natural polysaccharides. These polysaccharides are eco-friendly, nontoxic, and cheap to prepare. On the other hand, the attention in hydrocolloids and films has significantly enhanced, and their application is very promising in the food, pharmaceutical, perfumery and cosmetics, oil, paper, and textile industries. In this context, the present study is aimed to prepare silver nanoparticles by using viscous and superviscous exopolysaccharides of the rhizobacterium Paenibacillus polymyxa strains, CCM 1465 and 88A, and examined the properties of the resultant nanoparticles. We examined the synthesis and properties of silver nanoparticles under variable synthetic conditions by using exopolysaccharides of the rhizobacteria Paenibacillus polymyxa CCM 1465 and 88A. To prepare nanoparticles, we used different combinations of exopolysaccharide and silver nitrate concentrations: 1–10 mg/mL and 1–40 mM, respectively. The resulting solutions were alkalinized from pH 7.5–12 and heated for 15, 30, and 60 min to determine the optimal synthetic conditions. We found that the exopolysaccharides of strains CCM 1465 and 88A reduced silver ions and acted as nanoparticle stabilizers. The prepared spherical, oval, and triangular particles were stable and ranged in size from 2 to 40 nm, depending on the strain and on the experimental conditions. The nanoparticles showed antibacterial and antifungal activity against Escherichia coli K-12, Pseudomonas aeruginosa 50.3, Bacillus subtilis 26-D, and Fusarium oxysporum. In addition, the nanoparticles were active against SK-MEL-2 human melanoma cells. This finding shows the promise of further research on the exopolysaccharides of P. polymyxa 1465 and 88А in different fields of science, including medicine.

Using Cu-TCPP Nanosheets as Interlayers for High-Performance Organic Solvent Nanofiltration Membranes

The development of highly permeable and selective thin-film composite (TFC) membranes is essential for organic solvent nanofiltration (OSN) applications. However, overcoming the permeability–selectivity trade-off in polymer membranes remains highly challenging owing to the difficulty in controlling the thickness and nanostructures of the selective layers. In this study, TFC OSN membranes with sandwich-like structures were developed via interfacial polymerization on Cu-TCPP nanosheet-modified microporous polyvinylidene fluoride (PVDF) substrate surface. The interfacial polymerization was done by using mixed amine (polyethyleneimine and piperazine) in the aqueous phase and the 1,3,5-benzenetricarbonyl trichloride in the hydrophobic ionic liquid phase as monomers. It was found that the Cu-TCPP nanosheets of micrometer lateral dimensions and nanometer thickness (1.5 ± 0.6 nm) can be deposited on the PVDF substrate as an interlayer to facilitate the following interfacial polymerization reaction. The Cu-TCPP interlayer also can be served as a binder between the polyamide selective layer and the microporous PVDF substrate to enhance their mechanical strength. As compared with the PVDF/PA membrane, the PVDF/t-Cu-TCPP/PA membrane exhibited higher elongation (8.0 vs. 4.6%) while ensuring slightly lower tensile strength (36.0 vs. 48.6 MPa). Under optimal synthetic conditions, the TFC membranes could achieve 2.7 L m–2 h–1 bar–1, and 98.9% and 95.0% rejection to Brilliant Blue R (826 Da) and Congo red (697 Da), respectively, in ethanol. Furthermore, the membranes showed steady performance throughout the 36 h nanofiltration of the Rose bengal/ethanol mixture and exhibited good performance in the concentration of lecithin in methanol. Accordingly, this work highlights the potential of using thin metal–organic framework nanosheets as interlayers to develop high-performance TFC membranes for OSN applications.