Wood ash biocatalyst as a novel green catalyst and its application for the synthesis of benzochromene derivatives

Wood ash is a naturally alkaline derived substance containing organic and inorganic constituents. This study investigates the catalytic activity of wood ash as a heterogeneous catalyst for the synthesis of benzochromene derivatives. Several wood ash catalysts, comprising calcium- and potassium-rich carbonates, were prepared from different natural resources under various combustion temperatures. The prepared catalysts were characterized by Fourier transform infrared, scanning electron microscopy, energy dispersive X-ray analysis, transmission electron microscopy, and X-ray diffraction techniques. Catalytic efficiency of the resultant catalysts was tested in the synthesis of benzochromene derivatives. The experimental studies clarified that the catalyst prepared at 850 °C could efficiently expedite the formation of three-component synthesis of benzochromene derivatives in water at 80 °C with high yields. Indeed, alkali, alkaline metal, and metal oxides such as Al₂O₃, SiO₂, MgO, CaO, and Fe₂O₃, are widely utilized as both catalyst and catalyst support in the heterogeneous catalytic processes. The prepared wood ash catalysts (possessing metal oxides, e.g., CuO, Al₂O₃, SiO₂, and CaO) could effectively prompt the electrophilic activity of the carbonyl groups during the nucleophilic attack intermediate, enhancing the efficiency of the reactions.

Synthesis of Grafted Nanofibrillated Cellulose-Based Hydrogel and Study of Its Thermodynamic, Kinetic, and Electronic Properties

Hydrogels were synthesized by a copolymerization reaction of nanofibrillated cellulose (CNF) with acrylic acid (AA) and acrylamide (AM) and N,N-methylene-bis-acrylamide (MBA) as a cross-linker and their absorption performance as a function of composition was determined. Hydrogels with 4% by weight CNF had swelling of about 250 g/g and with 7% CNF about 200 g/g for water. Thermodynamic and kinetic studies of the reaction pathways and the electronic properties of the cellulose and monomers were investigated through density functional theory calculations. Thermodynamic investigations revealed that the radical formation of cellulose that initiates the hydrogel process can occur through the breaking of the homolytic covalent bonds C6-OH and C3-OH. The results show that the reaction of CNF with monomers is thermodynamically favorable in the decreasing order of AM, AA, and MBA. The kinetic study also indicates that the reaction kinetics of CNF with AM is faster than with AA which is much faster than with MBA. Overall, this study has elucidated some of the key chemical characteristics that impact the derivatization of nanocellulose structures to produce advanced renewable bioproducts.

Ultrasound-promoted Green Synthesis of pyrido[2,1-a]isoquinoline Derivatives and Studies on their Antioxidant Activity

Aims & Objective: An efficient procedure for the synthesis of pyrido[2,1-a]isoquinoline derivatives in excellent yields was investigated using catalyst-free multicomponent reaction of phthaladehyde, methylamine, activated acetylenic compounds, alkyl bromides and triphenylphosphine in water under ultrasonic irradiation at room temperature. In addition, Diels- Alder reactions of pyrido[2,1-a]isoquinoline derivatives with activated acetylenic compounds under ultrasonic irradiation are investigated in two procedures. The advantages of this procedure compared to report methods are short time of reaction, high yields of product, easy separation of product, clean mixture of reaction and green media for performing reaction. In addition, because of having isoquinoline core in synthesized compounds, in this research antioxidant activity of some synthesized compounds was studied.

MATERIALS AND METHODS

To a stirred mixture of phthalaldehyde 1 (2 mmol) and methylamine 2 (2 mmol) in water (3 mL) under ultrasonic irradiation was added to activated acetylenic compounds 4 after 20 min. Alkyl bromide 3 and triphenylphosphine 5 react in another pot in water (3 mL) under ultrasonic irradiation for 15 min. After this time, this mixture was added to the first pot. After completion of the reaction, the solid residue was separated by filtration and washed with Et2O to afforded pure title compound 6.

RESULTS

In this work, generation of pyrido[2,1-a]isoquinoline derivatives 6 are performed using phthalaldehyde 1, methylamine 2, α-halo substituted carbonyls 3, activated acetylenic compounds 4 and triphenylphosphine 5 in water under ultrasonic irradiation condition at room temperature in excellent yield at short time.

CONCLUSION

In summary, multicomponent reaction of phthaladehyde, methylamine, activated acetylenic compounds, alkyl bromides and triphenylphosphine in water under ultrasonic irradiation at room temperature produced pyrido[2,1-a]isoquinoline derivatives in excellent yields. Also, Diels-Alder reaction of pyrido[2,1-a]isoquinoline derivatives with activated acetylenic compounds and triphenylphosphine under ultrasonic irradiation is investigated in two procedures. Also, the antioxidant activities of 6a, 6c, 6g and 6i were evaluated by DPPH radical scavenging and ferric reducing power analyzes. The compounds 6a exhibit excellent DPPH radical scavenging activity and FRAP compared to synthetic antioxidants BHT and TBHQ. The chief benefits of our method are high atom economy, green reaction conditions, higher yield, shorter reaction times, and easy work-up, which agree with some principles of green chemistry.

Pd (II) Immobilized on Clinoptilolite as a Highly Active Heterogeneous Catalyst for Ullmann Coupling-type S-arylation of Thiols with Aryl Halides

BACKGROUND

There are a number of protocols for Ullmann coupling-type S-arylation reactions, many of them suffer from the use of homogenous and often corrosive catalyst, cumbersome workup procedures, and long reaction times. Besides, many of these reagents are expensive and non-recoverable, leading to the generation of a large amount of toxic waste particularly when large-scale applications are considered.

OBJECTIVE

The aim of this study was to prepare a new Pd catalyst bonded on the surface of zeolite as a heterogeneous catalyst.

METHODS

A heterogeneous palladium catalyst has been prepared by immobilizing Pd ions on Clinoptilolite. This novel developed heterogeneous catalyst was thoroughly examined for Ullmann coupling-type S-arylation reaction using different bases, solvents and 0.003 mg of the catalyst. The structural and morphological characterizations of the catalyst were carried out using XRD, TGA, BET and TEM techniques.

RESULTS

Highly efficient heterogeneous palladium catalyst has been developed by immobilizing Pd ions on Clinoptilolite, as one of the most abundant naturally occurring zeolites for Ullmann Sarylation. By using this method, we provide an efficient way to a wide variety of substituted thiolic compounds. Moreover, the catalyst is easily recovered using simple filtration and reused for 5 consecutive runs.

CONCLUSION

In this effort, we developed a new Pd catalyst bonded on the surface of zeolite as a substrate to prepare the heterogeneous catalyst. We demonstrate that this novel catalyst offers reliable and convincing data that may offer a valuable application in further developing the science and technology of Ullmann reaction protocols and allied industries. Additionally, the catalyst was reusable and kept its high activities over a number of cycles.

Molecular docking studies, biological evaluation and synthesis of novel 3-mercapto-1,2,4-triazole derivatives

Synthesis of bioactive heterocyclic compounds having effective biological activity is an essential research area for wide-ranging applications. In this study, a conventional methodology has been developed for the synthesis of a series of new 3-mercapto-1,2,4-triazole derivatives 4a-f. The purity and structure of the synthesized molecules were confirmed by ¹H NMR, ¹³C NMR and elemental analysis. In addition, the prepared compounds were screened for their anti-proliferative activity against three human cancer cell lines including A549 (lung cancer), MCF7 (breast cancer) and SKOV3 (ovarian cancer) using MTT reduction assay. All the tested compounds demonstrated remarkable cytotoxic activity with IC₅₀ values ranging from 3.02 to 15.37 µM. The heterocyclic compound bearing 3,4,5-trimethoxy moiety was found to be the most effective among the series displaying an IC₅₀ of 3.02 µM specifically against the ovarian carcinoma cancer cell line (SKOV3). Moreover, Annexin V-FITC/propidium iodide staining assay indicated that this compound can induce apoptosis in SKOV3 cells. Furthermore, cell cycle assay showed a significant cell cycle arrest at the G2/M phase in a dose-dependent manner for this compound. The molecular docking results was showed binding modes of potent compound 4d perfectly corroborated the suggestion of binding to the colchicine site. The entire results conclude that 3-mercapto-1,2,4-triazole derivatives can be synthesized by a green method for biological and pharmacological applications. New analogs of 3-mercapto-1,2,4-triazole potential derivatives for anti-proliferative activity were synthesized. Cytotoxic activity of all synthesized compounds was evaluated against tree human cancer cell lines: lung (A549), breast (MCF7) and ovarian (SKOV3).

Recent Advances in Applications of Voltammetric Sensors Modified with Ferrocene and Its Derivatives

This study is on current developments concerning ferrocene (FC) and its derivatives on the basis of electrochemical biosensors and sensors. The distinct physiochemical characteristics of FC have enabled the development of new sensor devices, specifically electrochemical sensors. Several articles have focused on the implementation of FC as an electrode constituent while discussing its electrochemical behavior. Furthermore, typical FC-design-based biosensors and sensors are considered as well as practical examples. The favorable design of FC-based biosensors and general sensors needs adequate control of their chemical and physical characteristics in addition to their surface immobilization and functionalization.

Rendering Redox Reactions of Cathodes in Li-Ion Capacitors Enabled by Lanthanides

Capacitors allow extremely fast charge and discharge operations, which is a challenge faced by recent metal-ion batteries despite having highly improved energy densities. Thus, combined type electric energy storage devices that can integrate high energy density and high power density with high potentials, can overcome the shortcomings of the current metal-ion batteries and capacitors. However, the limited capacities of cathode materials owing to the barren redox reactions are regarded as an obstacle for the development of future high-performance hybrid metal-ion capacitors. In this study, we demonstrate the redox-reaction-rendering effect of the much overlooked lanthanide elements when used as the cathode of lithium-ion capacitors using the mesoporous carbon (MC) as a matrix material. Consequently, these lanthanide elements can effectively enrich the redox reaction, thus improving the capacity of the matrix materials by more than two times. Typically, the Gd-elemental decoration of MC surprisingly enhances the capacity by almost two times as compared with the underacted MC. Furthermore, the La nanoparticles (NPs) decoration depicts the same behavior. Evident redox peaks were formed on the original rectangular cyclic voltammetry (CV) curves. This study provides the first example of embedding lanthanide elements on matrix materials to enrich the desired redox reactions for improving the electrochemical performances.

Recent developments in conducting polymers: applications for electrochemistry

Scientists have categorized conductive polymers as materials having strongly reversible redox behavior and uncommon combined features of plastics and metal. Because of their multifunctional characteristics, e.g., simplistic synthesis, acceptable environmental stability, beneficial optical, electronic, and mechanical features, researchers have largely considered them for diverse applications. Therefore, their capability of catalyzing several electrode reactions has been introduced as one of their significant features. A thin layer of the conducting polymer deposited on the substrate electrode surface can augment the electrode process kinetics of several solution species. Such electrocatalytic procedures with modified conducting polymer electrodes can create beneficial utilization in diverse fields of applied electrochemistry. This review article explores typical recent applications of conductive polymers (2016–2020) as active electrode materials for energy storage applications, electrochemical sensing, and conversion fields such as electrochemical supercapacitors, lithium-ion batteries, fuel cells, and solar cells.

Scientists have categorized conductive polymers as materials having strongly reversible redox behavior and uncommon combined features of plastics and metal.

Fabrication of magnetic iron oxide-supported copper oxide nanoparticles (Fe3O4/CuO): modified screen-printed electrode for electrochemical studies and detection of desipramine

The present investigation examines a sensitive electrochemical technique to detect desipramine through Fe₃O₄/CuO nanoparticles (NPs). Fe₃O₄/CuO NPs were synthesized via a coprecipitation procedure, and the products were characterized via energy disperse spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and vibrating sample magnetometer. The voltage–current curve and differential pulse voltammetry examinations of Fe₃O₄/CuO-modified screen-printed electrode (Fe₃O₄/CuO/SPE) were followed by the determination of electro-catalytic activities toward desipramine oxidation in a phosphate buffer solution (pH = 7.0). In addition, the value of diffusion coefficient (D = 3.0 × 10⁻⁶ cm² s⁻¹) for desipramine was calculated. Then, based on the optimum conditions, it was observed that the currents of the oxidation peak were linearly proportionate to the concentration of desipramine in the broad range between 0.08 and 400.0 μM and LOD of 0.03 μM (S/N = 3). Finally, our new sensor was successfully utilized to detect desipramine in the real samples, with reasonable recovery in the range of 97.2% to 102.7%.

The present investigation examines a sensitive electrochemical technique to detect desipramine through Fe₃O₄/CuO nanoparticles.

Understanding the mechanism of the 1,3-dipolar cycloaddition reaction between a thioformaldehyde S-oxide and cyclobutadiene: Competition between the stepwise and concerted routes

Changing the mechanism of the widely used 1,3-dipolar cycloaddition reaction from its usual asynchronous one-step pattern to the rarely observed stepwise form leads to the emergence of intermediates, side products, and other impurities. Thus, it is crucial to determine the nature of the mechanism of the 1,3-dipolar cycloaddition reaction between a special 1,3-dipole and a specified dipolarophile (by theoretical methods) before using them for synthesizing a desired product. In this study, therefore, we have investigated the possibility of some probable intermediates emergence in the 1,3-dipolar cycloaddition reaction between cyclobutadiene and thioformaldehyde S-oxide. The results showed that emergence of Int (B) (−52.1 kcal mol−1) via transition state (B-1) is favorable both thermodynamically and kinetically (in comparison with all other stepwise routes). That is, developing probable impurities should not be neglected at least in the cases of the reactions between some thioformaldehyde S-oxide and some dipolarophiles.

An efficient and reusable nano catalyst for the synthesis of benzoxanthene and chromene derivatives

Potassium fluoride impregnated on clinoptilolite nanoparticles (KF/CP NPs) was investigated as an efficient solid base catalyst for multicomponent condensation reaction. A broad range of aromatic aldehydes and enolizable compounds were condensed with 2-naphthol or 4-hydroxycumarine. The reaction was carried out under a solvent-free condition to give the corresponding benzoxanthene and pyrano [3,2-c]chromene derivatives in high yields. The low cost and availability of catalyst, novel and green procedure makes this strategy more useful for the preparation of tetrahydrobenzo[a]-xanthene-11-one and pyrano [3,2-c]chromene derivatives.

Experimental and computational studies on the synthesis of diastereoselective natural-based Meldrum spiro dibenzofuran derivatives

Herein, a novel route to achieve chiral Meldrum spiro dibenzofuran derivatives was developed, which involved a 2,2-dimethyl-1,3-dioxane-4,6-dione (Meldrum's acid)-mediated Knoevenagel reaction of substituted aryl halides, followed by a Diels–Alder reaction with euparin as a natural compound.

An amplified platform nanostructure sensor for the analysis of epirubicin in the presence of topotecan as two important chemotherapy drugs for breast cancer therapy

Epirubicin (EB) and topotecan (TP) are two major anticancer drugs that are used in breast cancer therapy with many side effects.

Green synthesis of silver nanoparticles using onion extract and their application for the preparation of a modified electrode for determination of ascorbic acid

A high-quality method for one-pot biosynthesis of silver nanoparticles (AgNPs) using onion extracts as reductant and stabilizer is reported. The synthesized AgNPs were characterized by ultraviolet-visible spectroscopy (UV-Vis), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). UV-Vis spectroscopy results showed that the AgNP absorption band was located at a peak of 397 nm in aqueous solution. Both XRD and TEM results confirmed that the AgNPs were mainly spherical with average diameters of 6.0 nm by TEM and about 5.3–10.2 nm calculated using XRD data. The ability of AgNPs to reduce charge transfer resistance was also investigated using electrochemical impedance spectroscopy. Finally, the effect of synthesized NPs on ascorbic acid signal was investigated by square wave voltammetry. The peak current of square wave voltammograms of ascorbic acid increased linearly with its concentration in the range of 0.4–450.0μM. The detection limit for ascorbic acid was 0.1μM.

Nano Clinoptilolite: Highly Efficient Catalyst for the Synthesis of Chromene Derivatives Under Solvent-Free Conditions

An efficient and selective synthesis of substituted chromene derivatives via three-component reaction of 4-hydroxycoumarin or 1,3-dicarbonyl compounds, activated acetylenic compounds and N-nucleophiles is described. The reaction was conducted under solvent-free conditions at 70°C using potassium fluoride impregnated on natural zeolite as a cheap and available solid base. The procedure has several advantages involving selectivity, excellent yields and a convenient work-up method.

CsF/clinoptilolite: an efficient solid base in SNAr and copper-catalyzed Ullmann reactions

CsF/clinoptilolite was found to be an efficient solid base catalyst for both SNAr and Ullmann ether reactions. A general and efficient one-step procedure was developed for the synthesis of biaryl ethers via direct coupling of electron-deficient aryl halides to phenols using CsF/clinoptilolite. The protocol was also applied to electron-rich aryl halides by addition of a catalytic amount of copper oxide nanoparticles. Both SNAr and Ullmann reactions were rapid and provided good to excellent yields.

Synthesis of a new class of furo[3,2-c]coumarins and its anticancer activity

A series of furo[3,2-c]coumarin derivatives 1a-d were synthesized and evaluated for their antiproliferative activity against MCF-7 breast and HCT-15 colon cancer cell lines using Sulfo-rhodamine B (SRB) assay. Compounds 1b and 1d showed higher antiproliferative activity than 1a and 1c. UV-Vis spectroscopy was used for DNA and BSA-binding affinity of the compounds 1b and 1d and gave overall affinity constants of K1b-DNA=8.1×10(3) M(-1), K1d-DNA=1.1×10(4) M(-1), K1b-BSA=5.1×10(4) M(-1), and K1d-BSA=7.6×10(4) M(-1). Our findings could provide new evidence showing the relationship between the chemical structure and anticancer activity of these new coumarin analogs.

Continuous and Cuffless Blood Pressure Monitoring Based on ECG and SpO2 Signals ByUsing Microsoft Visual C Sharp

BACKGROUND

One of the main problems especially in operating room and monitoring devices is measurement of Blood Pressure (BP) by sphygmomanometer cuff. Objective :In this study we designed a new method to measure BP changes continuously for detecting information between cuff inflation times by using vital signals in monitoring devices. This will be achieved by extraction of the time difference between each cardiac cycle and a relative pulse wave.

METHODS

Finger pulse and ECG signals in lead I were recorded by a monitoring device. The output of monitoring device wasinserted in a computer by serial network communication. A software interface (Microsoft Visual C#.NET ) was used to display and process the signals in the computer. Time difference between each cardiac cycle and pulse signal was calculated throughout R wave detection in ECG and peak of pulse signal by the software. The relation between time difference in two waves and BP was determined then the coefficients of equation were obtained in different physical situations. The results of estimating BP were compared with the results of sphygmomanometer method and the error rate was calculated.

RESULTS

In this study, 25 subjects participated among them 15 were male and 10 were female. The results showed that BP was linearly related to time difference. Average of coefficient correlation was 0.9±0.03 for systolic and 0.82±0.04 for diastolic blood pressure. The highest error percentage was calculated 8% for male and 11% for female group. Significant difference was observed between the different physical situation and arm movement changes. The relationship between time difference and age was estimated in a linear relationship with a correlation coefficient of 0.76.

CONCLUSION

By determining linear relation values with high accuracy, BP can be measured with insignificant error. Therefore it can be suggested as a new method to measure the blood pressure continuously.

KF/Clinoptilolite: an efficient promoter for the synthesis of thioethers

Potassium fluoride impregnated on natural zeolite as a new solid base system effectively catalyzes the coupling of thiophenols with electron-deficient fluoro-, chloro- and bromo-arenes in DMSO. This versatile and efficient solid base has been demonstrated to afford the corresponding desired products in good to excellent yields. This procedure provides a convenient, efficient and practical method for the preparation of diaryl thioethers.