No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Hydrolyzed Arabic gum-grafted-polyacrylonitrile@ zinc ferrite nanocomposite as an efficient biocatalyst for the synthesis of pyranopyrazoles derivatives
Abstract
A catalytic methodology for the effective synthesis of pyrazolopyrazole derivatives using a combination of hydrolyzed Arabic gum-g-polyacrylonitrile/ZnFe2O4 (Hyd AG-g-PAN/ZnFe2O4) catalyst, malononitrile, and aromatic aldehyde, hydrazine hydrate, and ethyl acetoacetate is described. This protocol relies on the use of environment-friendly heterogeneous catalyst based on zinc ferrite magnetic particles in combination with Arabic gum (AG) as the backbone, N, N methylene bisacrylamide (MBA) as a crosslinking agent, ammonium persulfate (APS) as an initiator, and alkaline solution for hydrolyzation. This bio-based catalyst with a soft three-dimensional cross-linked framework contains distinct acidic and basic sites and could be applied as a powerful catalyst for the one-pot synthesis of pyranopyrazoles derivatives. Using an external magnet, the superparamagnetic nanocomposite could be easily separated. Furthermore, the catalyst can well be utilized at least six times in subsequent reaction cycles before losing its activity. FT-IR, EDX, TGA, FESEM, VSM, and XRD methods were used to characterize the produced catalyst. Taking 0.01 g of catalyst at 80°C in a green solvent of water/ethanol, the greatest output of dihydropyrano [2,3-c] pyrazole was 96% in 15 minutes. A simple technique, short reaction time, high yield, and the catalyst's reusability and stability are just a few of the study's advantages.
... Due to the increasing demand for the reduction of NPs loss in their recovery from the reaction mixture, it is preferred to apply magnetic composites or inherently magnetic substances as adsorbents [38,39]. With this concern, the magnetic nanocomposite renders suitable and convenient systems for water decontamination and contaminant adsorption facets [40]. ...
... FTIR was utilized to investigate the step-by-step preparation of κ-carg-PAAm@Fe 3 O 4 -GO nanoadsorbent and to approve the presence of new functional groups in each preparation stage. As demonstrated in Fig. 4a, the prominent peak at 580 cm − 1 is related to the Fe-O bond, confirming the Fe 3 O 4 MNPs preparation [39]. Also, the peak in the area of 3400 cm − 1 is related to the O-H stretching vibration in the structure of Fe 3 O 4 MNPs [50]. ...
The κ-carrageenan-grafted-poly(acrylamide)/Fe 3 O 4-GO (κ-car-g-PAAm@Fe 3 O 4-GO) adsorbent was attained in three stages, utilizing grafted poly(acrylamide) (PAAm) onto κ-carrageenan (κ-car) in Fe 3 O 4 and graphene oxide (GO) presence. Various characteristic analyses were carried out to peruse the chemical properties, morphological features, thermal stability, magnetic behavior, and porosity of the prepared nanoadsorbent. According to the results obtained from the analyses, the prepared nanoadsorbent showed superparamagnetic behavior. It rendered a semicrystalline structure by Fe 3 O 4 presence in the amorphous matrix of the κ-car-g-PAAm. The SEM images exhibit well dispersion of the Fe 3 O 4 magnetic nanoparticles (MNPs) and lamellar GO sheets throughout the hydrogel context. Besides, along with the GO incorporation into the structure, the BET surface area (2.361 m 2 /g), pore volume (0.008 cm 3 /g), and pore size (137.49 nm) of the κ-car-g-PAAm@Fe 3 O 4-GO nanoadsorbent were higher than κ-car-g-PAAm@Fe 3 O 4. The maximum adsorption capacity (Q max) at an ambient temperature for CPFX adsorption was 1146.467 mg/g. These adsorption experiments' data were described by the Freundlich isotherm, and the pseudo-second-order explains the adsorption kinetics well. The retrievability of the prepared nanoadsorbent was studied and indicated that it could be isolated effectively and reused in three consecutive cycles without remarkable adsorption efficiency loss.
... The reaction is facilitated by Fe 3 O 4 @THAM-piperazine, a solid nanocatalyst, in a solvent mixture of water and ethanol at a temperature of 60°C. The current strategy presents several benefits, including convenient workup, rapid reaction time (8- Later on, the study by Zare's group [97] in 2023 presented an investigation into a catalytic methodology that enables the The experimental procedure described in this study utilizes an environmentally sustainable heterogeneous catalyst composed of zinc ferrite magnetic particles. This catalyst exhibits significant potential as a highly effective catalyst for the one-pot synthesis of pyrano-pyrazole derivatives 5. ...
In the present era, the concept of green in organic synthesis has a unique and irreplaceable place. Specifically, nanoparticle has gained much more attention due to its various properties related to the concept of green chemistry. In this context, magnetic nanoparticle has been widely used in the organic synthesis over last one decade. Among organic compounds, pyrazole and its scaffolds are recognized as a privileged structure as it represents a promising area for identification of lead structures towards the discovery of new synthetic drug molecules and other valuable candidates. Several commercial drugs such as Sildenafil, Rimonabant, Celecoxib and many other compounds in biological testing and preclinical evaluation, illustrate the wide therapeutic spectrum in this class of drug scaffolds. Accordingly, the magnetic nanoparticles have an irreplaceable place in the synthesis of pyrazole derivatives and it is a green and easy methodology to the organic chemists. The present manuscript represents the assimilation of literature pertaining to green aspects of magnetic nanoparticles for the synthesis of highly diversified and valuable derivatives of pyrazole.
... It has a relatively low adsorption capability for organic compounds. Through grafting co-polymerization of vinyl monomers in the presence of cross-linking agent onto this natural polymer, the three-dimensional (3D) structure hydrogel will be formed that shows remarkable mechanical properties Hassanzadeh-Afruzi et al., 2023c;Wang et al., 2015). Having a 3D structure will help in the capture of a variety of pollutants (V Desai et al., 2016;Li et al., 2018). ...
In this research study, a novel method, an in-situ growth approach, to incorporate metal-organic framework (MOF) into carrageenan-grafted- polyacrylamide-Fe3O4 substrate was introduced. Carrageenan-grafted-polyacrylamide-Fe3O4/MOF nanocomposite (kC-g-PAAm@Fe3O4-MOF-199) was fabricated utilizing three stages. In this way, the polyacrylamide (PAAm) was grafted onto the carrageenan (kC) backbone via free radical polymerization in the presence of methylene bisacrylamide (MBA) as cross-linker and Fe3O4 magnetic nanoparticles. Next, the kC-g-PAAm@Fe3O4 was modified by MOF-199 via an in-situ solvothermal approach. Several analyses such as Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-Dispersive X-ray Spectroscopy (EDX), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller (BET) demonstrated the successful synthesis of kC-g-PAAm@Fe3O4-MOF-199 magnetic hydrogel nanocomposite. The XRD pattern of magnetic hydrogel nanocomposite illustrated characteristic peaks of Fe3O4, neat kC, and MOF-199 with enhanced crystallinity in comparison with kC-g-PAAm@Fe3O4. TGA showed it has a char yield of 24 wt% at 800 °C. VSM confirmed its superparamagnetic behavior (with Ms of 8.04 emu g-1), and the BET surface area of kC-g-PAAm@Fe3O4-MOF-199 was measured at 64.864 m2 g-1, which was higher than that of kC-g-PAAm@Fe3O4 due to the highly porous MOF-199 incorporation with a BET surface area of 905.12 m2 g-1). The adsorption effectiveness of kC-g-PAAm@Fe3O4-MOF-199 for eliminating cephalosporin and quinolones antibiotics, i.e., Cefixime (CFX) and Levofloxacin (LEV) from the aquatic area was considered. Several experimental setups were used to evaluate the efficacy of adsorption, such as solution pH, amount of adsorbent, contact duration, and initial concentration. The maximum adsorption capacity (Qmax) of the prepared magnetic hydrogel nanocomposite was found to be 2000 and 1666.667 mg-1 for LEV and CFX using employing 0.0025 g of adsorbent. The Freundlich isotherm model well described the experimental adsorption data with R2CFX = 0.9986, and R2LEV = 0.9939. And the adsorption kinetic data were successfully represented by the pseudo-second-order model with R2LEV = 0.9949 and R2CFX = 0.9906. Hydrogen bonding, π-π interaction, diffusion, and entrapment in the hydrogel network all contributed to the successful adsorption of both antibiotics onto the kC-g-PAAm@Fe3O4-MOF-199 adsorbent. Other notable physicochemical properties include the three-dimensional structure and availability of the reactive adsorption sites. Moreover, the adsorption/desorption efficacy of magnetic hydrogel nanocomposites was not significantly diminished after four cycles of recovery.
Mercury (Hg) is a hazardous heavy metal, non-biodegradable and toxic, posing a serious threat to aquatic life and human health. Therefore, the removal of Hg ions from contaminated water using effective and eco-friendly adsorbents is necessary. In the present study, three magnetic chitosan-based organic–inorganic nanocomposites, such as CS-MnFe2O4, CS-MnFe2O4-CoS, and CS-MnFe2O4-CoS-MWCNTs, were designed and constructed to investigate their capacity for adsorbing Hg ions from aqueous solutions. The physicochemical properties of prepared composites were characterized by various analyses. The BET analyses indicated their high surface area and porous structure, and the N2 adsorption–desorption showed that the modification of CS in three stages by MnFe2O4 and crosslinking reaction, CoS preparation, and MWCNT incorporation resulted in increased N2 adsorption. The XRD confirms the synthesis of MnFe2O4 and CoS in the CS matrix and also the distinct peaks of MWCNTs. The CS-MnFe2O4-CoS-MWCNTs showed acceptable thermal stability with 45% char yields and superparamagnetic properties with magnetic saturation (Ms) of 16 emu g⁻¹. The interactive impacts of independent variables (pH, contact time, and adsorbent dosage) on the removal percentage of Hg(II) onto three prepared adsorbents, as well as the process optimization, were assessed by the Box-Behnken design. The optimum conditions were identified, and the data from the analysis of variance showed that the three independent factors (pH, contact time, and adsorbent dosage) significantly influenced the adsorption of Hg(II). The adsorption isotherm and thermodynamics analysis investigation showed that at low concentrations of Hg(II), the adsorption process was both endothermic and spontaneous for the studied adsorbents.
Recent advancements in metal–organic frameworks (MOFs) underscore their significant potential in chemical and materials research, owing to their remarkable properties and diverse structures. Despite challenges like intrinsic brittleness, powdered crystalline nature, and limited stability impeding direct applications, MOF‐based aerogels have shown superior performance in various areas, particularly in water treatment and contaminant removal. This review highlights the latest progress in MOF‐based aerogels, with a focus on hybrid systems incorporating materials like graphene, carbon nanotube, silica, and cellulose in MOF aerogels, which enhance their functional properties. The manifold advantages of MOF‐based aerogels in energy storage, adsorption, and catalysis are discussed, with an emphasizing on their improved stability, processability, and ease of handling. This review aims to unlock the potential of MOF‐based aerogels and their real‐world applications. Aerogels are expected to reshape the technological landscape of MOFs through enhanced stability, adaptability, and efficiency.
The Santa Barbara Amorphous-15-guar gum-grafted-poly (acrylic acid)/cobalt ferrite (SBA-15-GG-g-PAA/ CoFe 2 O 4) mesoporous adsorbent was prepared by graft copolymerization of acrylic acid (AA) onto guar gum (GG) in the Santa Barbara Amorphous-15 (SBA-15) substrate presence, followed by incorporating CoFe 2 O 4 magnetic nanoparticles (MNPs). Diverse analyses were conducted to identify the prepared mesoporous adsor-bent's chemical and morphological properties, thermal resistance, magnetic characteristics, surface area, and porosity. Based on the magnetic hysteresis loops, the mesoporous adsorbent rendered ferromagnetic behavior. According to TGA, it has char yields of 72 wt% at 800 • C and superparamagnetic behavior (Ms of 3.22 emu.g − 1). The crystalline structure and cubic phases of CoFe 2 O 4 MNPs in the GG-g-PAA amorphous matrix were demonstrated by XRD. The CoFe 2 O 4 MNP formation with partial aggregations onto smooth, nonporous, and regular surfaces of the GG was depicted by FESEM images. Also, the precisely-arranged hexagonal structure with cylindrical pores of SBA-15 was authenticated by FESEM images. Additionally, the SBA-15 substrate has increased the BET surface area of the prepared mesoporous adsorbent to 40.55 m 2 /g, which is higher than the composite without SBA-15 mesoporous silica. Several experimental setups were used to evaluate the effectiveness of adsorption, including pH of the medium (4-9), Adsorbent dosage (0.003-0.02 g), Interaction time (1-25 min), and Initial pollutant concentration (50-400 mg/L). Using 0.003 g of mesoporous adsorbent at 25 • C, chlorpyrifos (CPF) and malachite green (MG) had maximum adsorption capacities (Qmax) of 909.1 mg/g and 1000.0 mg/g, respectively. In this study, the Langmuir isotherm model fitted the adsorption data perfectly withR 2 MG = 0.9987 andR 2 CPF = 0.9994, and the pseudo-second-order model explained the adsorption kinetics with R 2 MG = 0.9644 and R 2 CPF = 0.9923. MG and CPF adsorption to the SBA-15-GG-g-PAA/CoFe 2 O 4 mesoporous adsorbent was successful due to hydrogen bonds, exchange interactions, diffusion, and entrapment in the hydrogel network. In addition to the three-dimensional structure, the mesoporous adsorbent has available adsorption sites for reactive molecules. The reusability of the SBA-15-GG-g-PAA/CoFe 2 O 4 was perused and showed that the mesoporous adsorbent can be separated efficiently and retrieved in three sequential cycles without considerable diminution in the adsorption efficiency.
Pyranopyrazoles are among the most distinguished, biologically potent, and exciting scaffolds in medicinal chemistry and drug discovery. Synthesis and design of pyranopyrazoles using functional modifications via multicomponent reactions (MCRs) are thoroughly found in synthetic protocols by forming new C–C, C–N, and C–O bonds. This review aims to focus on the biological importance of pyranopyrazoles as well as on a diverse synthetic approach for their synthesis using various catalytic systems such as acid-catalyzed, base-catalyzed, ionic liquids and green media-catalyzed, nano-particle-catalyzed, metal oxide-supported catalysts, and silica-supported catalysts. In this review, we have summarized data on the advancements in synthesizing pyranopyrazole from the last two decades to the mid-2023 and research papers describing the importance of these scaffolds. This review will be significant for synthetic organic chemists and researchers working in organic chemistry.
Graphical abstract
An effective method for synthesizing acridinedione derivatives using a xanthan gum (XG), Thiacalix[4]arene (TC4A), and iron oxide nanoparticles (IONP) have been employed to construct a stable composition, which is named Thiacalix[4]arene-Xanthan Gum@ Iron Oxide Nanoparticles (TC4A-XG@IONP). The process used to fabricate this nanocatalyst includes the in-situ magnetization of XG, its amine modification by APTES to get NH2-XG@IONP hydrogel, the synthesis of TC4A, its functionalization with epichlorohydrine, and eventually its covalent attachment onto the NH2-XG@IONP hydrogel. The structure of the TC4A-XG@IONP was characterized by different analytical methods including Fourier-transform infrared spectroscopy, X-Ray diffraction analysis (XRD), Energy Dispersive X-Ray, Thermal Gravimetry analysis, Brunauer–Emmett–Teller, Field Emission Scanning Electron Microscope and Vibration Sample Magnetomete. With magnetic saturation of 9.10 emu g⁻¹ and ~ 73% char yields, the TC4As-XG@IONP catalytic system demonstrated superparamagnetic property and high thermal stability. The magnetic properties of the TC4A-XG@IONP nanocatalyst system imparted by IONP enable it to be conveniently isolated from the reaction mixture by using an external magnet. In the XRD pattern of the TC4As-XG@IONP nanocatalyst, characteristic peaks were observed. This nanocatalyst is used as an eco-friendly, heterogeneous, and green magnetic catalyst in the synthesis of acridinedione derivatives through the one-pot pseudo-four component reaction of dimedone, various aromatic aldehydes, and ammonium acetate or aniline/substituted aniline. A combination of 10 mg of catalyst (TC4A-XG@IONP), 2 mmol of dimedone, and 1 mmol of aldehyde at 80 °C in a ethanol at 25 mL round bottom flask, the greatest output of acridinedione was 92% in 20 min.This can be attributed to using TC4A-XG@IONP catalyst with several merits as follows: high porosity (pore volume 0.038 cm³ g⁻¹ and Pore size 9.309 nm), large surface area (17.306 m² g⁻¹), three dimensional structures, and many catalytic sites to active the reactants. Additionally, the presented catalyst could be reused at least four times (92–71%) with little activity loss, suggesting its excellent stability in this multicomponent reaction. Nanocatalysts based on natural biopolymers in combination with magnetic nanoparticles and macrocycles may open up new horizons for researchers in the field.
The magnetic mesoporous hydrogel-based nanoadsornet was prepared by adding the ex situ prepared Fe3O4 magnetic nanoparticles (MNPs) and bentonite clay into the three-dimentional (3D) cross-linked pectin hydrogel substrate for the adsorption of organophosphorus chlorpyrifos (CPF) pesticide and crystal violet (CV) organic dye. Different analytical methods were utilized to confirm the structural features. Based on the obtained data, the zeta potential of the nanoadsorbent in deionized water with a pH of 7 was − 34.1 mV, and the surface area was measured to be 68.90 m²/g. The prepared hydrogel nanoadsorbent novelty owes to possessing a reactive functional group containing a heteroatom, a porous and cross-linked structure that aids convenient contaminants molecules diffusion and interactions between the nanoadsorbent and contaminants, viz., CPF and CV. The main driving forces in the adsorption by the Pectin hydrogel@Fe3O4-bentonite adsorbent are electrostatic and hydrogen-bond interactions, which resulted in a great adsorption capacity. To determine optimum adsorption conditions, effective factors on the adsorption capacity of the CV and CPF, including solution pH, adsorbent dosage, contact time, and initial concentration of pollutants, have been experimentally investigated. Thus, in optimum conditions, i.e., contact time (20 and 15 min), pH 7 and 8, adsorbent dosage (0.005 g), initial concentration (50 mg/L), T (298 K) for CPF and CV, respectively, the CPF and CV adsorption capacity were 833.333 mg/g and 909.091 mg/g. The prepared pectin hydrogel@Fe3O4-bentonite magnetic nanoadsorbent presented high porosity, enhanced surface area, and numerous reactive sites and was prepared using inexpensive and available materials. Moreover, the Freundlich isotherm has described the adsorption procedure, and the pseudo-second-order model explained the adsorption kinetics. The prepared novel nanoadsorbent was magnetically isolated and reused for three successive adsorption–desorption runs without a specific reduction in the adsorption efficiency. Therefore, the pectin hydrogel@Fe3O4-bentonite magnetic nanoadsorbent is a promising adsorption system for eliminating organophosphorus pesticides and organic dyes due to its remarkable adsorption capacity amounts.
Pyrazolopyridines are common scaffolds in various bioactive compounds, which have several therapeutic effects and unique pharmacological properties.
In the present article, we have reported a detailed study of the surface modification for magnetite nanoparticles (MNP, Fe3O4) using a natural, biodegradable, and biocompatible polymer. For this purpose, the cellulose was converted to its bromoacetylated derivative (BACell) by reacting with bromoacetyl bromide. Next, the MNPs were functionalized by the reaction of the hydroxyl groups with the methylene bromide of the prepared BACell to form Fe3O4/BACell. Then, the atom transfer radical polymerization (ATRP) method was developed for the covalent immobilization of the N-vinylpyrrolidone (NVP) on the Fe3O4/BACell surface to produce the Fe3O4/Cellulose-grafted NVP (Fe3O4/Cell-NVP) as a novel synthetic product. The Fourier transform infrared spectroscopy (FT-IR) indicated the presence of copolymer on the MNPs surface. Moreover, the thermogravimetric analysis (TGA) results of the Fe3O4/Cell-NVP indicated that there had been an acceptable percentage of the content of polymer chains on the surface of the Fe3O4 nanoparticles. Furthermore, the structure and magnetic properties of the Fe3O4/Cell-NVP were confirmed by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and scanning electron microscopy (SEM). The loading capacity and release profiles of Doxorubicin (DOX) as a model drug from the Fe3O4/Cell-NVP were determined by UV-Vis absorption measurement at λmax=483 nm. The results showed that the DOX-loaded nanoparticles had been well controlled during the release period of the DOX. Therefore, it seems that the Fe3O4/Cell-NVP is an appropriate candidate for the controlled and targeted delivery of cancer treatment.
Pyrazole and its derivatives are considered a privileged N-heterocycle with immense therapeutic potential. Over the last few decades, the pot, atom, and step economy (PASE) synthesis of pyrazole derivatives by multicomponent reactions (MCRs) has gained increasing popularity in pharmaceutical and medicinal chemistry. The present review summarizes the recent developments of multicomponent reactions for the synthesis of biologically active molecules containing the pyrazole moiety. Particularly, it covers the articles published from 2015 to date related to antibacterial, anticancer, antifungal, antioxidant, α-glucosidase and α-amylase inhibitory, anti-inflammatory, antimycobacterial, antimalarial, and miscellaneous activities of pyrazole derivatives obtained exclusively via an MCR. The reported analytical and activity data, plausible synthetic mechanisms, and molecular docking simulations are organized in concise tables, schemes, and figures to facilitate comparison and underscore the key points of this review. We hope that this review will be helpful in the quest for developing more biologically active molecules and marketed drugs containing the pyrazole moiety.
Sulfonated polymer-based materials, among heterogeneous catalysts, are frequently utilized in chemical transformations due to their outstanding chemical and physical durability. In this regard, a magnetic sulfonated melamine-formaldehyde resin (MSMF) catalyst was successfully prepared from a mixture of sulfonated melamine-formaldehyde and Fe3O4 nanoparticles in two steps. MSMF was used as a heterogeneous catalyst for the one-pot, three-component condensation of ben-zyl pyrazolyl naphthoquinones in water as a green solvent and 4-[(indol-3-yl)-arylmethyl]-1-phe-nyl-3-methyl-5-pyrazolones. The antimicrobial and antioxidant activities of catalyst, benzyl pyra-zolyl naphthoquinones, and 4-[(indol-3-yl)-arylmethyl]-1-phenyl-3-methyl-5-pyrazolones were evaluated using agar disk-diffusion and DPPH assays, respectively. The antioxidant activity of the catalyst and 4-[(indol-3-yl)-arylmethyl]-1-phenyl-3-methyl-5-pyrazolones was found to be 75% and 90%, respectively. Furthermore, catalyst, benzyl pyrazolyl naphthoquinones, and 4-[(indol-3-yl)-arylmethyl]-1-phenyl-3-methyl-5-pyrazolones exhibited antimicrobial activity against Staphylococcus aureus and Escherichia coli. In conclusion, MSMF is a superior catalyst for green chemical processes , owing to its high catalytic activity, stability, and reusability.
The tubular magnetic agar supported ZnS/CuFe2O4 nanocomposite was fabricated via a simple procedure. Next, various properties of this nanocomposite were studied by employing multiple characterization techniques including FT-IR, EDX, SEM, TEM,VSM, XRD, and TGA. Then, the catalytic and antibacterial applications were evaluated for the fabricated nanocomposite. Based on the experimental result, the nanocomposite showed excellent catalytic activity to promote the multicomponent reaction between ethyl acetoacetate, hydrazine hydrate, aromatic aldehydes, and malononitrile to synthesize a variety of dihydropyrano[2,3-c]pyrazole derivatives with high yields (89–95%) in acceptable reaction times (20–40 min) under mild reaction conditions. It can be efficiently recycled and re-work in six consequent runs without notable reduction in catalytic productiveness. Furthermore, its antibacterial activity was assessed against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria by the agar diffusion and plate-count methods. These results indicate that the width of the inhibition zone around the S. aureus (G⁺ bacterium) is more than that of E. coli (G⁻ bacterium). Moreover, the agar supported ZnS/CuFe2O4 nanocomposite exhibited strong prevention of the bacterial colonies’ growth.
Antibacterial materials have obtained much attention in recent years due to the presence of hazardous agents causing oxidative stress and observation of pathogens. However, materials with antioxidant and antibacterial activities can cause toxicity due to their low biocompatibility and safety profile, urging scientists to follow new ways in the synthesis of such materials. Ionic liquids have been employed as a green and environmentally solvent for the fabrication of electrically conductive polymers. In the present study, an antibacterial poly(p-phenylenediamine)@Fe3O4 (PpPDA@Fe3O4) nanocomposite was fabricated using [HPy][HSO4] ionic liquid. The chemical preparation of PpPDA@Fe3O4 nanocomposite was initiated through the oxidative polymerization of p-phenylenediamine by ammonium persulfate in the presence of [HPy][HSO4]. The PpPDA@Fe3O4 nanocomposite exhibited antibacterial properties against Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) bacteria. The PpPDA@Fe3O4 nanocomposite was employed as a heterogeneous nanocatalysis for one-pot synthesis of polyhydroquinoline derivatives using aromatic aldehyde, dimedone, benzyl acetoacetate, and ammonium acetate. Polyhydroquinoline derivatives were synthesized in significant yields (90-97%) without a difficult work-up procedure in short reaction times. Additionally, PpPDA@Fe3O4 nanocatalyst was recycled for at least five consecutive catalytic runs with a minor decrease in the catalytic activity. In this case, 11 derivatives of polyhydroquinoline showed in vitro antioxidant activity between 70-98%.
Background:
Although it was previously shown that prolonged prophylactic antibiotic exposure and multiple inadequate antibiotic therapies are independent risk factors for multidrug-resistant ventilator associated pneumonia there were no studies investigating whether pre-operative prophylactic dose of antibiotics changes oral microbiome and increases the risk of ventilator associated pneumonia. The aim of the study was to determine if pre-operative prophylactic dose of antibiotics affects the oral microbiome, increases the colonization with Gram-negative bacteria and subsequent risk of ventilator associated pneumonia.
Subjects and methods:
Mechanically ventilated adult patients receiving surgical antibiotic prophylaxis were included in the study. The presence of Gram negative microorganisms in the pre-prophylactic and post-prophylactic oral swabs and tracheal aspirates, as well as the occurrence of ventilator associated pneumonia, were analyzed.
Results:
Number of patients colonized with Gram negative bacteria in post- prophylactic oral swab was significantly higher compared to oral swab taken before prophylactic antibiotic. On the other hand, the number of patients with Gram- negative bacteria in tracheal aspirates remained similar as in post- prophylactic oral swabs. Moreover, we found that presence of Gram- negative bacteria in both pre- and post- prophylactic oral swabs was in the positive correlation with the presence of Gram- negative bacteria in tracheal aspirates.
Conclusions:
This study showed increased colonization of oral cavity with Gram- negative bacteria after preoperative prophylactic antibiotics. Furthermore, receiving two prophylactic antibiotics from WHO Watch list increased the incidence of Gram- negative bacteria in oral swabs and tracheal aspirates, and the risk of ventilator associated pneumonia development.
Extreme pressure (EP) and antiwear (AW) additives are necessary for boundary lubrication. However, their mechanisms and physical and chemical properties remain unclear. EP and AW additives were reviewed to fill gaps in theoretical and industrial applications. Compounds containing chlorine, sulfur, and phosphorus elements were first used in boundary lubrication because of thermal reaction with metal to form film characteristics. First, the mechanisms of traditional EP and AW additives were analyzed, the physical and chemical properties were compared, and properties affecting factors were studied. Traditional EP and AW additives are not environmentally friendly, but nanoparticle EP and AW additives are excellent substitutes. The mechanisms of nanoparticle EP and AW additives were summarized. The influence of nanoparticle structure parameters, concentration, and media polarity on properties was studied. Second, the influence law of non-polar chain length on traditional EP and AW additives was revealed. The improvement interval of traditional EP and AW additives on the performance of the base fluid was determined. The structural advantage of low crystallinity onion-like and multilayer sheet-like low wrinkle effect of nanoparticles was explained. The particle size design principle attached to the surface roughness and size-dependent melting inhibition mechanism was established. The influence of concentration and media polarity on nanoparticle properties was obtained. Finally, the research of minimum amount matching database and mathematical selection model for traditional EP and AW additives and the molecular dynamics analysis of surface-modified nanoparticles and the development of green general-purpose additives based on molecular design are prospected.
Due to the stringent requirements of carbon emissions, traditional cutting using a large amount of mineral-based metal cutting fluid for lubrication no longer fulfilled the rigorous requirements of policies and standards. Nanofluid minimum quantity lubrication has been proven to be a new process to achieve clean manufacturing. However, due to adhesive contact friction, lubricant droplets cannot effectively penetrate the tool and workpiece interface during continuous turning. Changing the microstructure of the rake face of the tool, such as the micro-texture, may provide a geometric channel for the diffusion of the lubricant. However, the effects of micro-texture geometry and arrangement on the film formation and tribological properties of droplets have not been revealed yet. The spreading behavior of minimum quantity lubrication atomized microdroplet on the textured surface was calculated by hydrodynamic modeling. It was proven that the microchannel can effectively store the lubricating medium atomized by compressed air pneumatics. Furthermore, a comparative experiment was conducted on the influence of the texture arrangement on the cutting performance through the turning experiment. Results show that the microgrooves in the direction perpendicular to the main cutting edge obtained the lowest cutting force. The feed force, radial force, and tangential force were reduced by 13.46%, 16.23%, and 6.34%, respectively. Meanwhile, the texture arranged parallel to the cutting edge and crosswise increased the cutting force. The arrangement of the texture perpendicular to the main cutting edge direction obtained the optimal workpiece surface, the smallest chip curling radius, and the smoothest chip surface. Under the optimized texture arrangement, the anti-wear and anti-friction properties of nanofluids in the cutting area are enhanced.
In this study, a novel mesoporous nanocomposite was fabricated in several steps. In this regard, SBA-15 was prepared by the hydrothermal method, next it was magnetized by in-situ preparation of Fe3O4 MNPs. After that, the as-prepared SBA-15/Fe3O4 functionalized with 3-minopropyltriethoxysilane (APTES) via post-synthesis approach. Then, the guanidinylated SBA-15/Fe3O4 was obtained by nucleophilic addition of APTES@SBA-15/Fe3O4 to cyanimide. The prepared nanocomposite exhibited excellent catalytic activity in the synthesis of dihydropyrano[2,3-c]pyrazole derivatives which can be related to its physicochemical features such as strong basic sites (presented in guanidine group), Lewis acid site (presented in Fe3O4), high porous structure, and high surface area. The characterization of the prepared mesoporous nanocomposite was well accomplished by different techniques such as FT-IR, EDX, FESEM, TEM, VSM, TGA, XRD and BET. Furthermore, the magnetic catalyst was reused at least six consequent runs without considerable reduction in its catalytic activity.
An efficient magnetic polymer‐based nanomaterial was prepared in three main steps including synthesis of polyacrylonitrile (PAN), modification of PAN with melamine, and magnetization of the PAN@melamine compound by in situ construction of Fe3O4 MNPs. The novel PAN@melamine/Fe3O4 organometallic nanocomposite was well characterized by various techniques such as Fourier transform infrared (FT‐IR) spectroscopy, energy dispersive X‐ray (EDX) spectroscopy, thermogravimetric analysis (TGA), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD) pattern, and vibrating sample magnetometer (VSM) curve. Afterward, the fabricated nanocomposite was used as a heterogeneous catalyst in two multicomponent reactions (MCRs) for the synthesis of biologically active dihydropyrano[2,3‐c]pyrazole and 2‐amino‐3‐cyano 4H‐pyran derivatives. The corresponding products were obtained in excellent yields without a complicated work‐up process. Besides, the prepared nanocatalyst could be recycled and reused at least five consecutive runs in both MCRs without a considerable decline in its catalytic activity. The PAN@melamine/Fe3O4 nanocomposite was prepared, characterized and then utilized as an efficient nanocatalyst with dual active sites in the synthesis of dihydropyrano[2,3‐c]pyrazole and 2‐amino‐3‐cyano 4H‐pyran derivatives.
Heterogeneous catalysis plays a crucial role in many chemical processes, including advanced organic preparations and the design and synthesis of new organic moieties. Efficient and sustainable catalysts are vital to ecological and fiscal viability. This is why green multicomponent reaction (MCR) approaches have gained prominence. Owing to a broad range of pharmacological applications, pyranopyrazole syntheses (through the one-pot strategy, employing sustainable heterogeneous catalysts) have received immense attention. This review aimed to emphasise recent developments in synthesising nitrogen-based fused heterocyclic ring frameworks, exploring diverse recyclable catalysts. The article focused on the synthetic protocols used between 2010 and 2020 using different single, bi- and tri-metallic materials and nanocomposites as reusable catalysts. This review designated the catalysts’ efficacy and activity in product yields, reaction time, and reusability. The MCR green methodologies (in conjunction with recyclable catalyst materials) proved eco-friendly and ideal, with a broad scope that could feasibly lead to advancements in organic synthesis.
Today, most synthetic methods are aimed at carrying out reactions under more efficient conditions and the realization of the twelve principles of green chemistry. Due to the importance and widespread applications of tetrazoles in various industries, especially in the field of pharmaceutical chemistry, and the expansion of the use of nanocatalysts in the preparation of valuable chemical reaction products, we decided to use an (Fe3O4@[email protected])CO2H nanocatalyst in this project. In this study, the synthesis of the nanocatalyst (Fe3O4@[email protected])CO2H was explained in a step-by-step manner. Confirmation of the structure was obtained based on FT-IR, EDX, FE-SEM, TEM, XRD, VSM, DLS, TGA, H-NMR, and CHNO analyses. The catalyst was applied to the synthesis of 5-substituted-1H-tetrazole and 1-substituted-1H-tetrazole derivatives through multi-component reactions (MCRs), and the performance was assessed. With advances in science and technology and increasing environmental pollution, the use of reagents and methods that are less dangerous for the environment has received much attention. Therefore, following green chemistry principles, with the help of the (Fe3O4@[email protected])CO2H salen complex as a nanocatalyst that is recyclable, cheap, safe, and available, the use of water as a green solvent, and reduced reaction times, the synthesis of tetrazoles can be achieved.
A heterogeneous, magnetically recoverable nanocomposite, Fe3O4@[email protected](ii) was prepared by immobilization of a novel Ni(ii) Schiff base complex on Fe3O4@NFC nanoparticles followed by treatment with melamine. This trinuclear catalyst has been characterized using several analytical techniques including FT-IR, TEM, Fe-SEM, EDX, DLS, ICP, TGA, VSM, and XRD. It was used as an efficient catalyst for one-pot solvent-free synthesis of 1,4-dihydropyridine and poly-hydro quinoline derivatives through Hantzsch reaction. This catalyst showed remarkable advantage over previously reported catalysts due to suitable conditions, short reaction time, high efficiency and lower catalyst load and timely recovery of the magnetic catalyst. Moreover, the effects of Fe3O4@[email protected](ii) nanoparticles on thein vitroproliferation of human leukemia cell line (k562) and human breast cancer cells (MDA-MB-231) were investigated. The results of MTT and Hochest assays suggested that the nanoparticles could effectively inhibit the proliferation of these cancer cells in a time- and concentration-dependent manner.
A new catalytic system consisting of Mn or Co nanoparticles supported on different materials (celite, zeolite, activated carbon, CeO2, ZnO, MgO, Nb2O5) have been studied for styrene epoxidation. The catalysts were easily prepared from commercially available starting materials. Reaction conditions were optimized by testing different solvents, reaction temperatures, oxidizing agents, and optimal catalyst loading. CoNPs/MgO and TBHP as a co-oxidant, in refluxing ACN, allowed total conversion to the epoxide with excellent yield and high selectivity.
The release of coloured effluents from various dying industries are of great concern due to the challenge involved in the treatment process. In present work, response surface methodology (RSM) and artificial neural network (ANN) were used to predict the color removal using adsorption process. Water hyacinth (WH) was used as an economical adsorbent for color removal from aqueous solution in a batch system. The individual effect of influential parameter viz. initial pH, MB (dye) concentration, and the adsorbent dose were studied using the central composite design of RSM. The RSM result was used as an input data along with final pH (non-controllable parameter) after adsorption to train the ANN model. Color removal of 96.649% was obtained experimentally at the optimized condition. A comparison between the experimental data and model results shows a high correlation coefficient (R2RSM = 0.99 and R2ANN = 0.98) and showed that the two models predicted MB removal indicating WH can be used as an adsorbent for color removal from dye wastewater.
Gum arabic-OPO3H2 (GA-OPO3H2) as a unique natural-based green catalyst was synthesized by the reaction of phosphorus pentoxide with gum arabic. The structure and properties of the catalyst were studied via several analysis methods such as FT-IR, MAPPING, EDS, SEM, XRD, and TGA. The efficiency of the above-mentioned catalyst was investigated for the synthesis of naphtho-1,3-oxazines via a pseudo-four-component reaction of primary amines, formaldehyde, and 2-naphthol under the solvent-free grinding condition at room temperature using an electrical mortar-heater. The obtained results indicated that GA-OPO3H2 is a highly efficient green catalyst for the synthesis of naphtho[1,2-e][1,3]oxazines with high yields, simple workup, and benign reaction condition.
Today, due to the developing need for inexpensive catalysts, recyclable magnetic nanocatalysts immobilized on polysaccharides possess many advantages over classical heterogeneous catalysts. However, cellulose has been an appealing material in catalysis science and technology. In this work, by controlling the interaction between the inorganic complexes and the support material, we designed a high activity nanostructured combination of a magnetic nanoparticle Fe3O4@NFC@Co(II) terminated complex as a multi-nuclear catalyst. This protocol involves an environment friendly approach using cobalt acetate. The magnetic nanostructure Fe3O4@NFC@Co(II) can be used as a novel, green, and a powerful catalyst that demonstrates a short reaction time, high yield and easy procedure for the cascade Knoevenagel–Michael-cyclocondensation reaction for the one-pot synthesis of 4H-pyrans and pyranopyrazoles. The superparamagnetic nanocomposite could be conveniently separated by using an external magnet. Moreover, the catalyst could be reused at least five times in new reaction runs without a noticeable loss of activity. The prepared catalyst was characterized by FT-IR, XRD, VSM, FESEM, EDAX, TEM, ICP, and TGA techniques. The experiments were achieved with good yields and implied that the catalytic method was effective and convenient for heterocyclic synthesis.
The magnetic biocompatible rod‐like ZnS/CuFe2O4/agar organometallic hybrid catalyst was designed and prepared based on a natural macromolecule (agar) through a green and convenient method using inexpensive, nontoxic, and easily available substances. Then, the as‐prepared catalyst was characterized by several techniques such as Fourier transform‐infrared spectroscopy, energy‐dispersive X‐ray analysis, scanning electron microscopy image, transmission electron microscopy, vibrating sample magnetometry curve, X‐ray diffraction pattern, and thermogravimetric analysis. Eventually, the catalytic application of the ZnS/CuFe2O4/agar nanobiocomposite was assessed in sequential Knoevenagel condensation–Michael addition reaction of dimedone, malononitrile, and different substituted aromatic aldehydes for the synthesis of 2‐amino‐tetrahydro‐4H‐chromene‐3‐carbonitrile derivatives. Some notable strengths of this environmentally benign catalyst include simplicity of catalyst preparation and separation, affording desired products with satisfactory yields (81%–97%) in very short reaction times (3–18 min), and with no need for complicated work‐up processes. Experimental tests showed that the catalyst can be successfully reused after five sequential runs without significant reduction in its catalytic efficiency. The biocompatible rod‐like ZnS/CuFe2O4/agar organometallic catalyst prepared based on agar, conveniently. It was characterized by FTIR, EDX, SEM, TEM, TGA, VSM and XRD analyses. Investigation of its catalytic application in the synthesis of 2‐amino‐tetrahydro‐4H‐chromene‐3‐carbonitrile derivatives showed that desired products produced with high yields (81%–97%) in very short reaction times (3–18 min). The catalyst can be reused after five sequential runs without significant reduction in its catalytic efficiency.
A novel nanomagnetic catalyst has been synthesized by immobilization of triethanolamine lactate cellulose with Fe3O4 NPs. The prepared catalyst has been used as an efficient and recoverable catalyst for the regioselective synthesis of pyrazolo quinolones by the three-component reaction of dimedone, 5-amino pyrazolone and aromatic aldehydes in ultrasound condition. This economical catalyst provides high yields of products, short experimental time and easy workup for green synthesis of pyrazolo[3,4-b]quinolone compounds. Theoretical studies have been employed to investigate the reaction mechanism by using the B3LYP/6-311G method. Electronic parameters of all components have been determined in order to reorganize the role of components in the reaction mechanism.
Graphic abstract
Ultrasound-assisted, mild and highly efficient route for the one-pot multicomponent reaction of ethyl acetoacetate, hydrazine hydrate, aromatic aldehydes and barbituric acid has been developed for the construction of bioactive heterocyclic moieties in a single molecular framework. The synthesis of tri-heterocyclic fused pyrazolopyranopyrimidines promoted by β-Cyclodextrin as a biomimetic catalyst and water as an eco-friendly reaction medium. This environmentally beningn protocol offers selective synthesis of pyrazolopyranopyrimidine derivatives without any side product with excellent yield in shorter duration. The reusability and recyclability of catalyst is carried out in simple way. Also, this method provides various advantages such as metal free synthesis, cost-effective catalyst, no column chromatography and offers easy isolation of products with gram scale synthesis.
Graphic Abstract
Open image in new window
A promising application of sulfonated carboxymethylcellulose (SCMC) as a green heterogeneous catalyst in the synthesis of pyrano[2,3c]pyrazole derivatives has been studied here. Sulfonated carboxymethyl cellulose was synthesized through a new, green and efficient pathway. The synthesized SCMC catalyst was characterized using Fourier transform infrared (FT‐IR) spectroscopy, energy dispersive X‐ray (EDX) analysis, X‐ray diffraction (XRD) pattern, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Its catalytic ability was then investigated in the pyranopyrazole synthesis. The SCMC as a biopolymer‐derivative solid acid catalyst indicated catalytic activity in the one‐pot multi‐component synthesis of pyrano[2,3c]pyrazole derivatives using the reaction of ethyl acetoacetate, hydrazine hydrate, malononitrile, and various aldehydes in ethanol as a green solvent. The key features of this methodology are operational simplicity, use of a stable, recoverable, and non‐toxic catalyst, simple purification of the product by non‐chromatographic methods, high yields, environment‐friendly reaction, and economically lucrative.
In this work, a facile protocol for the preparation of a new cellulose-based functionalized magnetic nanocomposite catalyst is described. The structure and morphology of the prepared nanomaterial was characterized by scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction patterns, and Fourier transform infrared spectroscopy analyses. Then, its catalytic activity was investigated in the synthesis of 2,4-dihydropyrano[2,3-c]pyrazole and spiro[indoline-3,4′-pyrano[2,3-c]pyrazole derivatives through a one-pot four-component reaction between isatin or aldehydes or acetophenones, ethylacetoacetate, hydrazine hydrate, and malononitrile or ethylcyanoacetate in short reaction times, high yields, and mild conditions. The nanocomposite was simply separated by an external magnet and reused several times without remarkable loss of activity.
Pyrazole and its derivatives are considered a pharmacologically important active scaffold that possesses almost all types of pharmacological activities. The presence of this nucleus in pharmacological agents of diverse therapeutic categories such as celecoxib, a potent anti-inflammatory, the antipsychotic CDPPB, the anti-obesity drug rimonabant, difenamizole, an analgesic, betazole, a H2-receptor agonist and the antidepressant agent fezolamide have proved the pharmacological potential of the pyrazole moiety. Owing to this diversity in the biological field, this nucleus has attracted the attention of many researchers to study its skeleton chemically and biologically. This review highlights the different synthesis methods and the pharmacological properties of pyrazole derivatives. Studies on the synthesis and biological activity of pyrazole derivatives developed by many scientists around the globe are reported.
Prebiotics have great potential as agents to improve or maintain a balanced intestinal microflora to enhance health and wellbeing. They are non-digestible (by the host) food ingredients that have a beneficial effect through their selective metabolism in the intestinal tract. Key to this is the specificity of microbial changes.Thanks to the methodological and fundamental research of microbiologists, enormous progress has been made in understanding the gut microbiota. A large number of human intervention studies have been performed that have demonstrated that dietary consumption of certain food products can result in statistically significant changes in the composition of the gut microbiota in line with the prebiotic concept. The concept prebiotics is to enhance the growth of beneficial bacteria in the lower intestine. There is much interest in increasing the numbers and activities of beneficial bacteria (Bifidobacteria) in the large gut, preferably at the expense of more harmfulbacteria. The focus of this review has been to point out the prebiotic effects (bifidogenic effects) of acacia gum and inulin. Some effects attributed to selected prebiotics have been proved by clinical trials, while others have been acquired on the basis of in vitro tests.
This study aims to treat heavy metal pollutants in water by applying red mud particle waste. An experiment on the static adsorption of heavy metal ions Pb2+ (or Cd2+ and Cu2+) by red mud particles was carried out, and the influences of the type of heavy metal ion, ion concentration, pH value, red mud dosage, reaction time, and temperature on adsorption performance were explored. The competitive adsorption mechanisms of various coexisting heavy metal ions by red mud particles were compared. The red mud samples loaded and not loaded with heavy metal ions were detected by zeta potential measurement, scanning electron microscopy, and Fourier transform infrared spectrometry. The adsorption strength of red mud particles for heavy metal ions was ranked in the sequence of Pb2+, Cd2+, and Cu2+, while increasing temperature enhanced their adsorption. When the initial pH values were 4.3, 5.0, and 3.6 for Pb2+, Cd2+, and Cu2+ solutions, the removal peaks were 94.5%, 92.8%, and 78.1%, respectively. The preferred order of adsorption for red mud was Pb2+, Cd2+ and then Cu2+ under the competitive mechanism of binary/ternary systems due to the discrepancy in the functional groups of red mud particles loaded with different heavy metal ions.
A novel environmentally friendly polymer-based catalytic system was fabricated for the synthesis of biologically active pyrazolopyridine derivatives. Nanocatalyst was fabricated in three-step including (I) synthesis of the copper ferrite magnetic nanoparticles (MNPs) via co-precipitation method, (II) graft copolymerization of acrylonitrile onto acacia gum (AG) backbone using ammonium persulfate (APS) as an initiator, and N, N'-methylene bisacrylamide (MBA) as a crosslinker in combination with as-prepared copper ferrite, and (III) modification reaction of the as-prepared hydrogel using hydroxylamine hydrochloride reagent to achieve acacia gum-grafted- polyamidoxime/CuFe2O4 (AG-g-PAO/CuFe2O4) hydrogel nanocatalyst. The fabricated hydrogel nanocatalyst was well characterized by different techniques. The results revealed that the fabricated hydrogel nanocatalyst exhibited high thermal stability with ~ 40% char yield at 800 °C. The existence of many acidic and basic sites such as hydroxyl, carboxylic acid, amidoxime, amide, as well as Cu2+ in three-dimensional cross-linked structure caused it was showed a great catalytic performance in the pyrazolopyridine derivatives synthesis. The various corresponding products were synthesized in remarkable yields (90–97%) without difficult work-up procedure in short reaction times (15–40 min). Furthermore, the hydrogel catalyst showed superparamagnetic behavior, so it could be magnetically collected from the reaction mixture and recycled for at least five successive cycles without considerable loss of activity.
A novel organic/inorganic biosorbent hydrogel nanocomposite based on Arabic Gum-grafted-polyamidoxime and CuFe2O4 magnetic nanoparticles (AG-g-PAO/CuFe2O4) was prepared in three steps. The prepared hydrogel nanocomposite was well characterized using Fourier transform infrared (FT-IR), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), CHN, zeta potential, and Brunauer-Emmett-Teller (BET) analyses. The adsorption efficiency of the AG-g-PAO/CuFe2O4 for removing an organophosphorus pesticide (OPP) (chlorpyrifos) from aqueous solutions was studied. Effect of different experimental conditions such as the pH of the solution, adsorbent dosage, contact time, initial concentration on adsorption efficiency was evaluated. The experimental adsorption data described well by the Langmuir isotherm model and the maximum adsorption capacity (Qmax) of the prepared biosorbent for chlorpyrifos was found 769.23 mg/g. The adsorption kinetic data were well fitted by the pseudo-second-order model. It was suggested that the chlorpyrifos was adsorbed onto AG-g-PAO/CuFe2O4 hydrogel biosorbent mainly through electrostatic interaction and hydrogen bonding. The result of adsorption-desorption experiments revealed that the AG-g-PAO/CuFe2O4 can be excellently regenerated and reused after three sequential runs without a considerable decline in its adsorption performance.
Livestock wastewater is an important reservoir of antibiotic resistance genes (ARGs) and antibiotic residues. Membrane fouling is one of the most challenging problems confining the operation and application of membrane bioreactor (MBR). In this work, a novel iron-carbon micro-electrolysis (ICME)/electro-biocarriers-MBR system was established to explore the performance of pollutant removal and anti-fouling for an actual livestock wastewater. A light-weight porous ceramsite (bulk density 0.98 g/cm³) was used as the MBR biocarriers. The electrons generated from iron corrosion in the ICME tank traveled through external wires to the stainless steel membrane modules of MBR and the protons were transferred from the MBR tank to the ICME tank through a salt bridge, thus producing a spontaneous electric field. Under the optimized conditions, the system exhibited chemical oxygen demand removal of 76.0%, total suspended solids removal of 100%, antibiotic removal of 86.4%, NH4⁺-N removal of 91.1%, and ARGs reduction of 6-8 orders of magnitude. The quality of the final effluent can reach the national Class I-A discharge criteria. Adding ceramsite could not only effectively improve biodegradation performance but also alleviate membrane fouling through the migration and enrichment of microbial flora to the ceramsite. The self-generated electric field had no significant improvement effect on pollutant removal, but exhibited good anti-membrane fouling behavior which could be ascribed to (i) oxidization of membrane foulants by the electrochemical products (such as H2O2 and •OH radicals), and (ii) electrostatic repulsion of negatively charged foulants and bacterial cells. The bacterial community structure and diversity were studied using high-throughput pyrosequencing, and the results demonstrated the roles of electric field and biocarriers in enrichment of anti-fouling communities and repulsion of biofouling-creating communities.
A huge number of nitrogen-containing heterocyclic compounds are ubiquitous in natural products, pharmaceuticals, and bioactive molecules. Among these, the pyranoindole represents an important structural motif, as it constitutes the central subunit in both the biologically active natural products and therapeutic agents. Talathermophilins, notoamides, norgeamides, carneamides, and versicamides are examples of naturally occurring pyranoindoles, while the well-known etodolac and pemedolac are a tetrahydropyrano[3,4-b]indole deriving from synthetic procedures. Besides the well-known antiinflammatory and fibrinolytic activity, molecules comprising the pyranoindole framework have been demonstrated to exhibit various biological activities, such as antiulcer, antidepressant, analgesic, and antiproliferative. Herein, we report the most common natural and synthetic products bearing a pyranoindole nucleus, their syntheses, and biological activities.
In this research, the synthesis of piperazine immobilized on nano-ZnO-sulfuric acid (PINZS) as a new piperazine-based nano-reagent is reported. After identification of PINZS using different techniques including XRD (X-ray powder diffraction), TGA (thermogravimetric analysis), FT-IR (Fourier transform infrared spectroscopy), FESEM (field emission scanning electron microscopy), and EDX (energy-dispersive X-ray) analysis, this reagent is efficiently used for the synthesis of 1-(benzothiazolylamino) phenylmethyl-2-naphthols and pyrimido[1, 2-a]benzimidazoles via a domino Knoevenagel/Michael sequence which identified acceptable reaction times (7–45 min.), great yields (up to 98%) and ease of the preparation, separation, and recovery of PINZS (for three times) as the most important features of this protocol.Graphic abstractUse of PINZS in the synthesis of some important heterocycles.
Due to its excellent temperature resistance, 316 L stainless steel (SS) is widely used in integral impellers; however, as the engine performance requirements have increased, the shape of integral impellers has become increasingly complex. Directed energy deposition (DED), with a high production rate and low cost, is used to directly fabricate complex structural geometries. Nevertheless, the surface quality is lower than that achieved by conventional methods, i.e., milling. To overcome this problem, a novel hybrid approach with DED followed by a subtractive milling process within a single workstation is developed. This method can directly produce internal and highly complex structural parts with ideal dimensional accuracy. However, the process parameters and mechanical properties of DED and subtractive thermal milling (starting milling temperature of 200-300℃) after each deposition of a set of layers have rarely been evaluated. The purpose of this study is to address these research limitations. The densification, phase composition, microstructure and mechanical behaviour are studied, and a correlation between process parameters and performance is newly established. The results indicate that the nearly fully dense 316 L SS specimens exhibit high microhardness and tensile strength under the optimum process parameters, which is attributed to the high density and fine microstructure. Moreover, the highest tensile strength (683.3 MPa) among all tensile samples is obtained with v = 8 mm/s. The tensile strength values for wrought (hot work-annealed), wrought (cold-worked), cast samples, and for the industry requirement for 316 L SS are 480, 574, 552 and 450 MPa, which are 42.97%, 19.56%, 24.33%, and 52.51% lower, respectively, than that for the hybrid DED and thermal milling process. The test results and a comparison analysis show that the components from the hybrid DED and thermal milling process can satisfy the industry requirements for 316 L SS.
This research, for the first time, reports the design and development of a heterogeneous nano-catalyst based on sodium ions (Na+) incorporation in Technical University of Delft (TUD-1) mesoporous silica for Knoevenagel condensation reaction. Facile one-step fabrication of Na-TUD-1 nano-catalysts (varying Si/Na ratio as 100–5) was demonstrated using the sol–gel route. The catalytic performance of Na-TUD-1 was evaluated as a base heterogeneous catalyst in Knoevenagel condensation reaction, which took place under conventional and microwave irradiations conditions using ethanol as a solvent. Na-TUD-1 exhibited superior catalytic activity in comparison to available homogeneous base catalysts such as sodium ethoxide. The Na-TUD-1 nano-catalyst demonstrated identical performance till the fourth run along with high stability and negligible leaching of Na. Moreover, the use of microwave heating reduced the reaction time from 240 to 20 min only with a TOF of 0.58 min−1. Such excellent performance of Na-TUD-1 heterogeneous nano-catalysts will certainly increase its industrial acceptability to achieve affordable and efficient waste-effluent treatments.
A series of fluorescence-containing indazole-fused ring systems were made with the support of g-C3N4/CuO as a catalyst via non-conventional (microwave) method. We have synthesized g-C3N4/CuO nanocomposites by mechanochemical process; further, its morphology and composition were studied using various instrumental techniques like Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). Also, we have synthesized pyrimido[1, 2-b] indazole-4-yl methanol motifs without any solvent in single-step methodology utilizing microwave irradiation. The pyrimido[1, 2-b] indazole-4-yl methanol motifs were optimized using response surface methodology (RSM). This preparation was effortlessly accessible, and the overview of the substrates was authorized. The pyrimidoindazole core structures exhibit the most remarkable photo physical properties. Most of the pyrimidoindazole scaffold appears in solvatochromism and excited with blue–green fluorescence shift while using ethyl acetate as solvent. This result indicates that synthesized pyrimidoindazole core motifs have prodigious potential as fluorophores which will help us to study several applications.
Graphic abstract
Electrospinning has garnered significant attention in view of its many advantages such as feasibility for various polymers, scalability required for mass production, and ease of processing. Extensive studies have been devoted to the use of electrospinning to fabricate various electrospun nanofibers derived from carbohydrate gum polymers in combination with synthetic polymers and/or additives of inorganic or organic materials with gums. In view of the versatility and the widespread choice of precursors that can be deployed for electrospinning, various gums from both, the plants and microbial-based gum carbohydrates are holistically and/or partially included in the electrospinning solution for the preparation of functional composite nanofibers. Moreover, our strategy encompasses a combination of natural gums with other polymers/inorganic or nanoparticles to ensue distinct properties. This early established milestone in functional carbohydrate gum polymer-based composite nanofibers may be deployed by specialized researchers in the field of nanoscience and technology, and especially for exploiting electrospinning of natural gums composites for diverse applications.
In this study Guar gum based Cu(II) Schiff's base complex (GG-Cu) has been synthesized and characterized by FT-IR, PXRD, UV-Visible, TGA, XPS, FESEM, TEM, EDAX, solid-state NMR, Elemental mapping, CHNS and AAS analysis. This moiety has been found to be an efficient heterogeneous catalyst for selective oxidation reactions. Fifteen model reactions have been carried to establish the catalytic behavior of GG-Cu, and five of these yield novel products. The ease of separation of catalyst from the reaction mixture simply by filtration is an added advantage; furthermore the catalyst can be reused up to five times without significant loss of catalytic activity. The overall concept of developing newer, efficient and environmental benign catalysts with ease of separation and recycling ability has been successfully demonstrated. All of the isolated products were fully characterized on the basis of their physical and spectral data.
Dextrin is a low molecular weight polysaccharide obtained from natural resources. Due to exceptional properties such as chemical structure, having extreme reactive functional groups, low cost, commercial availability, non-toxicity and biocompatibility, it can be introduced as a green organocatalyst. The fabrication of hybrid materials from natural polymers and synthetic inorganic materials constructs compounds with new features, abilities and applications. Therefore, magnetic dextrin nanobiocomposite was prepared using a simple chemical co-precipitation. Then, it was characterized by Fourier transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray (EDX) analysis, vibrating sample magnetometer (VSM) curve, scanning electron microscopy (SEM) image, X-ray diffraction (XRD) pattern, thermogravimetric analysis (TGA) and inductively-coupled plasma atomic emission spectroscopy (ICP-AES) analysis. Subsequently, to evaluate the catalytic performance of the synthetic hybrid catalyst, it was tested for the synthesis of biologically active polyhydroquinoline derivatives by four-component condensation reactions of aromatic aldehyde, ethyl acetoacetate, dimedone, ammonium acetate in ethanol under refluxing conditions. Experimental observations indicated some advantages of the present method, such as the use of green and biopolymer-based catalyst, simple procedure, mild reaction conditions, short reaction times (15–45 min), appropriate yield of products (70–95%) and catalyst reusability after five consecutive runs without considerable catalytic performance decrease.
In this research, we have used Fe3O4@nano‐cellulose–OPO3H as magnetic bio‐based nanocatalyst for the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones via condensation of 2‐aminobenzamide and different aldehydes. The major advantages of the present methodology are good yields, ecofriendly catalyst, and easy workup. In this research, we have used Fe3O4@nano‐cellulose–OPO3H as a magnetic bio‐based nanocatalyst for the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones via condensation of 2‐aminobenzamide and different aldehydes. The major advantages of the present methodology are good yields, ecofriendly catalyst, and easy workup.
Gum polysaccharides are derived from renewable sources. They are readily available, inexpensive, non-hazardous and eco-friendly. Depending upon the source, gums may be categorized as microbial gums, plant exudate gums or seed gums. Naturally occurring gum carbohydrates find multiple applications in the biomedical arena, compared with synthetic compounds, because of their unique structures and functionalities. Gums and their biocomposites are preferred for sustained drug delivery because they are safe and edible as well as more susceptible to biodegradation. The present review provides a state-of-the-art conspectus on the industrial and biomedical applications of antimicrobial gum-based biocomposites. Different kinds of gums polysaccharides will first be addressed based on their sources. Metal-, carbon- and organic-based nanostructures that are used in gum nanocomposites will then be reviewed with respect to their industrial and biomedical applications, to provide a backdrop for future research.
The pyranopyrazole derivatives have many biological activities. They were synthesized via a four-component coupling of aromatic aldehyde, malononitrile, ethyl acetoacetate and hydrazine hydrate. In this study, dihydropyrano[2,3-c]pyrazoles have been synthesized in the presence of nano-Al2O3/BF3/Fe3O4 as catalyst in water/ethanol under reflux conditions. The catalyst was removed from the mixture of reaction by an external magnet and was reusable for several times without any loss of its activity. The obtained pyranopyrazoles were characterized by various methods such as FT-IR, ¹HNMR and melting point. Easy purification, clean and convenient procedure are some advantages of this method.
In this study, we propose a nonlinear attachment-detachment model with hysteresis for the transport of suspension-colloidal particles (SPs) in porous media. The proposed model uses an adsorption function and scanning desorption isotherms to model the deposition process of SPs. This model shows that increasing or decreasing the seepage velocity results in substantial changes in the penetration concentration of SPs, which is closely related to the adsorption hysteresis and the deposition dynamics of SPs. Studies show that previous linear attachment-detachment models probably result in an overestimation of the adsorption capacity of porous media. Static deposition tests and dynamic transport experiments using pulse injection were performed to calibrate the transport parameters. The effects of the seepage velocity, injection concentration and particle size on the transport parameters and reaction rate constant were investigated. Experiments were also performed under variable injection concentrations and seepage velocities. The results show that there is good agreement between the simulated and experimental breakthrough curves (BTCs).
Selective copper (Cu) recovery from wastewater mitigates environmental pollution and is economically valuable. Mesoporous silica adsorbents, SBA-15, with amine-grafting (SBA-15-NH2) and manganese loading along with amine-grafting (Mn-SBA-15-NH2) were fabricated using KMnO4 and 3-aminopropyltriethoxysilane. The characteristics of the synthesized adsorbents were evaluated in detail in terms of its crystal structure peaks, surface area and pore size distribution, transmission electron microscope and X-ray photoelectron spectroscopy. The results established the 2.08mmol/g of Cu adsorption capacity on Mn-SBA-15-NH2. Furthermore, in a mixed heavy metal solution, high selective Cu adsorption capacity on Mn-SBA-15-NH2 (2.01mmol/g) was achieved while maintaining 96% adsorption amount as that of a single Cu solution. Comparatively, Cu adsorption on SBA-15-NH2 decreased by half due to high competition with other heavy metals. Optimal Cu adsorption occurred at pH5. This pH condition enabled grafted amine group in Mn-SBA-15-NH2 to form strong chelating bonds with Cu, avoiding protonation of amine group (below pH5) as well as precipitation (above pH5). The adsorption equilibrium well fitted to Langmuir and Freundlich isotherm models, while kinetic results were represented by models of linear driving force approximation (LDFA) and pore diffusion model (PDM). High regeneration and reuse capacity of Mn-SBA-15-NH2 were well established by its capacity to maintain 90% adsorption capacity in a multiple adsorption-desorption cycle. Cu was selectively extracted from Mn-SBA-15-NH2 with an acid solution.
Alginic acid as a linear polysaccharide derived from natural resources can be used in the role of a green catalyst in organic reactions. Properties such as reactivity, renewability and biodegradability make this polysaccharide as an eco-friendly organocatalyst. In the synthesis of organic compounds, the development of effective methods for the synthesis of 4H-pyran compounds is important because of its extensive medicinal and biological activities. In this study, ZnFe2O4@alginic acid nanocomposite was synthesized by a simple procedure. Then, it was utilized as a green, cost-effective and heterogeneous catalyst in the synthesis of 2-amino-3-cyano-4H-pyran derivatives with a one-pot three‐component reaction between various aromatic aldehydes, dimedone and malononitrile. Conventional methods such as Fourier transform infrared (FT‐IR) spectroscopy, X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM) image, energy-dispersive X-ray (EDX) analysis, vibrating sample magnetometer (VSM) curve and inductively-coupled plasma atomic emission spectroscopy (ICP-AES) analysis were employed to characterize the prepared nanocomposite. This protocol offers some beneficial features such as green catalyst, mild reaction conditions, simple procedure, easy workup, short reaction times and significant yield of the products. The magnetic properties of the nanocomposite caused its easy separation by using an external magnetic field from the reaction mixture without significant loss of its catalytic activity.
In this study, a green magnetic nanocatalyst based on natural clay was fabricated. Magnetic nanoparticles were loaded on halloysite nanotubes (HNTs) and poly(ethylene imine) (PEI) was covalently grafted onto the surface of HNTs. The morphology and chemistry of the Fe3O4@HNTs-PEI nanocomposite was fully characterized by Fourier transform infrared (FT-IR) spectroscopy spectra, field-emission scanning electron micrograph (FE-SEM) images, thermogravimetric analysis (TGA), energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) pattern and vibrating sample magnetometer (VSM) curve analyses. These characteristics confirmed the successful synthesis of the nanocomposite. The catalytic performance of Fe3O4@HNTs-PEI was utilized for the synthesis of pyranopyrazole derivatives. This heterogeneous catalyst exhibited high efficiency in green media under mild reaction conditions at room temperature and can be easily recovered from the reaction mixture by using an external magnet and reused for at least eight times without any significant decrease in catalytic activity.
Innovative therapeutic heterocycles having precisely thiadiazolyl-pyranopyrazole fragments were prepared by using the ecofriendly synthetic route. Entire compounds formed in quantitative yields. All the composites tested for their antimicrobial effectiveness against four microbial, two beneficial fungi's and accurately measured the minimum inhibitory concentrations (MIC and MBC/MFC), along with some initial structure activity relationships (SARs) also discussed. From the biological outcomes, the motif 6f provided an outstanding activity against all six pathogens. The possible presence of a nitro substituent on this composite may undoubtedly enhance the activity. In addition, amalgams 6d, 6g and 6l displayed promising antimicrobial results. This may be justified to the presence of electron capture group attached to the benzene ring, while the combinations 6j and 6k were zero effect towards all bacterial strains. The other compounds were excellent to low antimicrobial efficiency. The intriguing point was observed that all the active compounds had in common immense antibacterial effectiveness on Gram-negative bacteria than Gram-positive one and more antifungal activity on A. niger compare to other fungus. All things considered and suggested that this outstanding green synthetic approach is used to develop biological active compounds. On top of that, biological results confirmed that these biologically energetic motifs suitable for additional preclinical examine with the aim of standing novel innovative drugs.
A new magnetic catalyst was prepared through the reaction of silanol groups, on the surface of silica-coated Fe3O4 magnetic nanoparticles, with (3-chloropropyl)triethoxysilane followed by hexamethylenetetramine and chlorosulfonic acid. The obtained magnetic catalyst was characterized using thermogravimetric analysis, vibrating sample magnetometry, scanning electron microscopy and energy-dispersive X-ray analysis. Its catalytic activity was investigated in the synthesis of pyranopyrazole compounds, and the results were excellent regarding high yield of the products and short reaction time.
Nitrogen-containing heterocyclic compounds and their derivatives have historically been invaluable as a source of therapeutic agents. Pyrazole, which has two nitrogen atoms and aromatic character, provides diverse functionality and stereochemical complexity in a five-membered ring structure. In the past decade, studies have reported a growing body of data on different pyrazole derivatives and their innumerable physiological and pharmacological activities. In part, such studies attempted to reveal the wide range of drug-like properties of pyrazole derivatives along with their structure–activity relationships in order to create opportunities to harness the full potentials of these compounds. Here, we summarize strategies to synthesize pyrazole derivatives and demonstrate that this class of compounds can be targeted for the discovery of new drugs and can be readily prepared owing to recent advances in synthetic medicinal chemistry.
Inhibition of α-glucosidase enzyme activity is a reliable approach towards controlling post-prandial hyperglycemia associated risk factors. During the current study, a series of dihydropyrano[2,3-c] pyrazoles (1-35) were synthesized and evaluated for their α-glucosidase inhibitory activity. Compounds 1, 4, 22, 30, and 33 were found to be the potent inhibitors of the yeast α-glucosidase enzyme. Mechanistic studies on most potent compounds reveled that 1, 4, and 30 were non-competitive inhibitors (Ki = 9.75 ± 0.07, 46 ± 0.0001, and 69.16 ± 0.01 μM, respectively), compound 22 is a competitive inhibitor (Ki = 190 ± 0.016 μM), while 33 was an uncompetitive inhibitor (Ki = 45 ± 0.0014 μM) of the enzyme. Finally, the cytotoxicity of potent compounds (i.e. compounds 1, 4, 22, 30, and 33) was also evaluated against mouse fibroblast 3T3 cell line assay, and no toxicity was observed. This study identifies non-cytotoxic novel inhibitors of α-glucosidase enzyme for further investigation as anti-diabetic agents.