Category Archives: ChemistrySelect

Applications of Highly Stable Silver Nanoparticles from Garcinia mangostana Pericarp Extract: Bioactivities, Catalysis, and Optical Sensing

Posted on 9 October 2023 by

This study demonstrates the benefits of green synthesis of silver nanoparticles (AgNPs) from Garcinia mangostana pericarp extract for multiple applications in bioactivities, catalysis, and sensing. This implies and orients the various practices of AgNPs and evidence of the great potential of the green chemistry pathway.

Abstract

In this work, the Garcinia mangostana pericarp aqueous extract was utilized as an efficient reducing agent for the phyto-synthesis of eco-friendly silver nanoparticles (GM/AgNPs (GMAs)). Characterization of the as-synthesized material revealed the optimal synthesis conditions of 1 mL of the extract, 1.6 mL of AgNO₃, and 1 mL of pH 10 buffer solution at 70 °C for 30 min of reaction. The formation and distribution of quasi-spherical silver nanoparticles were elucidated with an average particle size of 22.12±1.106 nm, whilst the colloidal system of GMAs also possessed a negative surface charge (−25.4 mV) with such low particle instability parameters (PIP), signifying great stability even after 8 weeks. Furthermore, the material demonstrated excellent bioactivities, wherein a good inhibitory was acquired towards both P. aeruginosa and S. aureus. Besides, the synthesized GMAs provided great catalytic reduction performances, which removed 98.75, 96.55, and 90.85 % of RhB, MO, and 4-NP, respectively, within 120 s. Along with a low detection limit for surveyed heavy metal ions as well as H₂O₂ in specific concentration ranges, the phyto-synthesized GMAs can be efficaciously employed in a wide range of environmental applications, namely in the medical and wastewater remediation sectors.

Fabrication and characterization of ZSM‐5@Silicalite‐1 core‐shell composites and their application in hexane catalytic cracking

Posted on 9 October 2023 by nJiale Zhu, nFan Yang, nSiyan Yan, nHaidan Wu, nXuedong Zhun

Core-shell structure catalysts fabricated demonstrated a volcanic trend in olefins yields with the increase of shell thickness. Controlling shell thickness to 150 nm could manifest the best performance with 27.9 % higher in olefins yields and dramatically improved catalyst lifetime compared with the core catalyst ascribed to passivation of external acid sites by protective shell outside the core to inhibit side reactions considerably.

Abstract

A variety of core-shell structure catalysts with different shell thicknesses were fabricated by hydrothermal coating. Multiple characterization technologies including XRD, SEM, N₂ adsorption-desorption, NH₃-TPD and IR were employed to explore the physicochemical properties of all the samples, demonstrating that the shell layer was successfully introduced on the exterior of the core. The results of hexane cracking disclosed that with the increase of shell thickness, olefins selectivities increased continuously accompanied by a minor decrease of hexane conversion. Only when controlling the shell thickness to 150 nm could manifest the best performance with light olefins yields of 51.1 %, much higher than those of 23.2 % on the core catalyst. On the other hand, the catalyst lifetime was greatly improved, which presented a decrease of only 2.8 % in hexane conversion, relative to 9.7 % on the core catalyst during the reaction period of 80 h. Above exciting phenomenon was attributed to the growth of protective shell outside the core, which passivated the external acid sites greatly, thus side reactions were inhibited dramatically. It is firmly believed that our work provided a novel reference for the production of light oil cracking catalyst in industry, which will make up for the shortage of olefins considerably.

Simultaneous Quantification of Major Bio‐Active Diterpenoid Lactones and Flavonoids in Andrographis paniculata (Burm. F.) Nees: LC‐ESI‐MS/MS Method Validation and Uncertainty Determination

Posted on 9 October 2023 by

LC-ESI-MS/MS method for simultaneous determination of five bioactive diterpenoid lactones (andrographolide, neoandrographolide, andrograpanin, 14-deoxy-11,12-didehydroandrographolide and andrographiside) and two flavonoids (7-O-methylwogonin and apigenin) in Andrographis paniculata. The method was precise, sensitive, selective and accurate for quantification of the seven phytochemicals and could be used for quality control of the herb.

Abstract

Diterpenoid lactones and flavonoids are major bio-active compounds of therapeutically important medicinal herb Andrographis paniculata (Burm.F.) Nees. The lack of a validated protocol for quality assurance of raw herbs is a significant issue for its wider use. A validated LC-ESI-MS/MS method developed using MRM mode for simultaneous determination of five diterpenoid lactones (andrographolide, neoandrographolide, andrograpanin, 14-deoxy-11,12-didehydroandrographolide and andrographiside) along with two flavonoids (7-O-methylwogonin and apigenin). Chromatographic separation of seven analytes was achieved within 14 minutes in Alltima column (100×4.6 mm, 3 μm) using gradient elution. The developed method was accurate (97.77 to 101.17 %; recovery), precise (intra-day and inter-day %RSD of 0.22–2.19 and 1.01–3.68, respectively) and linear (R² >0.99). To meet the regulatory obligation, uncertainty associated with the measurement was also evaluated by using different validation parameters. Developed method was successfully employed in analysing the analytes quality in different solvent extracts. Total diterpenoid lactones and flavonoids (DTLF) content was recorded highest in methanol extract (45.47 μg g⁻¹) followed by ethanol (39.23 μg g⁻¹) and lowermost content found in petroleum ether extract (0.38 μg g⁻¹) in triplicate samples. Since the method is simple, rapid, sensitive, and accurate, it has potential role for quality evaluation of A. paniculata and its derived formulation.

Efficient Synthesis of 2,5‐Disubstituted Chalcogenophenes by a One‐pot, Stepwise Glaser Coupling – Cycloaddition Sequence

Posted on 9 October 2023 by nShiju Li, nFanmin Liu, nChao Qian, nShaodong Zhoun

The mild and highly efficient constructions of 2,5-disubstitued thiophenes, selenophenes and tellurophenes are achieved by using a one-pot, two-step protocol that combine Cu-catalyzed Glaser coupling with LiNH₂-mediated cycloaddition. And the DMSO/EtOH mixture solvent is found to short the reaction time and improve the reaction yield by promoting the production of S₃⋅⁻ and stabilizing the transition state.

Abstract

A mild and efficient method for the synthesis of 2,5-disubstituted chalcogenophenes is reported. This method involves two steps of reactions via one-pot approach by employing commercially available and cost-effective alkynes and element chalcogen. Further, by using LiNH₂ as the promoter and DMSO/EtOH as the solvent, Cu-catalyzed Glaser coupling-cycloaddition processes are dramatically enhanced that a diverse range of chalcogenophenes can be obtained in good to excellent yields under mild conditions. Controlled experiments show that trisulfur radical anion (S3⋅⁻) is the key intermediate and DMSO/EtOH serves as the hydrogen source, while alcohol may facilitate the transition state.

Co Ion‐, NiS2‐ and CNT‐Co‐Doped Nanoflower/Hollow Spherical NiO Nanocomposites for Efficient Electrocatalytic Oxidation of Methanol

Posted on 9 October 2023 by

In this work, nanoflower and hollow spherical NiO was synthesized by a simply hydrothermal method and then modified by Co, NiS₂ and carbon nanotubes (CNTs). electrochemical test proves that it has rich Active site, and excellent reaction kinetics. and good stability and conductivity were confirmed by I-t and EIS test. The results showed that the catalyst has good methanol electrocatalytic oxidation activity and the current density could reach 203.46 mA ⋅ cm⁻² at a voltage of 0.8 V, catalytic performance surpasses most nickel based materials.

Abstract

Nowadays, the development and utilization of clean energy are becoming increasingly urgent. Among them, methanol is a new, clean, and efficient energy source. Therefore, more and more studies are focusing on methanol anodic oxidation (MOR). In this work, nanoflower and hollow spherical NiO was synthesized by a simply hydrothermal method and then modified by Co ion, NiS₂ and carbon nanotubes (CNTs). The optimal Co/NiO(f)/NiS₂−CNT exhibits flower-like morphology with a larger specific surface area, enlarged electrochemically active surface area and higher conductivity, which improve the electron transfer ability and electrocatalytic activity compared with pure NiO(f), NiO(f)/NiS₂, NiO(f)/NiS₂−CNT and hollow spherical Co/NiO(hs)/NiS₂−CNT. The current density is ultrahigh of 203.46 mA ⋅ cm⁻² at 0.8 V, which is 36 times higher than pure NiO(f) and almost 2 times higher than Co/NiO(hs)/NiS₂−CNT. Therefore, this work offers a highly efficient and stable NiO based catalyst for methanol oxidation reaction.

New Coumarin−Thiosemicarbazone Based Zn(II), Ni(II) and Co(II) Metal Complexes: Investigation of Cholinesterase, α‐Amylase, and α‐Glucosidase Enzyme Activities, and Molecular Docking Studies

Posted on 9 October 2023 by

New coumarin−thiosemicarbazone compound and their zinc (II) 2 a, nickel (II) 2 b, and copper (II) 2 c metal complexes were synthesized and characterized then these complexes were determined for some metabolic enzyme inhibitory activities. The Ki values of the new complexes for BChE, AChE, and α-glucosidase enzymes were obtained in the ranges of 115.84–276.07, 31.68–117.08, and 22.56–47.82 μM, respectively. Of all the compounds studied, bis-3-benzyl-7,8-dimethoxycoumarin−thiosemicarbazonato zinc(II) is the most potent drug against AChE.

Abstract

New coumarin−thiosemicarbazone compounds and their zinc(II), nickel(II), and copper(II) metal complexes were synthesized and characterized. The inhibitory activities of these new coumarin−thiosemicarbazone-based metal complexes against butyrylcholinesterase (BChE), acetylcholinesterase (AChE), α-amylase, and α-glucosidase were determined. The results showed that all the synthetic compounds exhibited potent inhibitory activities against all targets, as compared to the standard inhibitors, as revealed by the half-maximal inhibitory concentration (IC₅₀) and the inhibitory constant (Ki) values. The Ki values of the new complexes for BChE, AChE, and α-glucosidase enzymes were obtained in the ranges of 115.84–276.07, 31.68–117.08, and 22.56–47.82 μM, respectively. Moreover, molecular docking studies provided support for the conclusion that coumarin−thiosemicarbazone zinc(II) (−102.34; −10.41 kcal/mol) and coumarin−thiosemicarbazone cobalt(II) complexes (−25.46; −9.49 kcal/mol) act as dual inhibitors for both AChE and α-amylase species. Furthermore, coumarin−thiosemicarbazone cobalt(II) (−39.46 kcal/mol) and coumarin−thiosemicarbazone nickel(II) complexes (−39.41 kcal/mol) demonstrated potential as inhibitors of α-glucosidase. Of all the compounds studied, bis-3-benzyl-7,8-dimethoxycoumarin−thiosemicarbazonato zinc(II) is the most potent drug against AChE.

Adsorptive Recovery of Heavy Metal Ions from Aquatic Systems Using Metal‐Organic Frameworks: A Perspective in the Sustainable Development of Nanomaterials

Posted on 9 October 2023 by

Adsorptive decontamination of wastewater using Metal-Organic Frameworks to recycle toxic heavy metals into precious precursors for the development of smart nanomaterials

Abstract

Rapid industrialization in the developing countries has facilitated the unwanted mixing of wastes into the already depleting sources of potable, domestic and industrial water. In particular, the mixing of toxic heavy metal wastes into the aquatic resources have not only increased the scarcity of water at the different levels of usage but also hygiene of the ecosystem is further threatened by the presence of abysmal quality of aquatic environment around the living world. Thus, it has become quite imperative to mitigate such problems through the removal of such water contaminants at the sources before supplied for a specific purpose. In this direction, among the other available mass transfer techniques, specific and efficient adsorption of heavy metal species on the nanomaterials such as metal-organic frameworks (MOFs) are found to be a promising method of heavy metal ions recovery. This reports targets to provide a new perspective into heavy metal ions removal from wastewater as a rationale for sustainable nanomaterial engineering through the recycling of toxic metal species as precious precursors in the synthesis of nanomaterials. Decades of exploring materials sciences led to the generation of groundbreaking materials of nanoscale regime, which has advanced myriad avenues of science and technology, viz. electronic, energy, biomedical, environmental, agriculture applications, and more. In this regard, nanotechnology has had a global impact by several folds, which can be observed in all day-to-day facilities. This perspective aims to conceptualize a strategy of wastewater decontamination through the adsorptive retrieval of heavy metal species to be subsequently recycled in the design of smart nanomaterials.

Development of a consolidated heterogeneous catalytic process for the selective oxidation of carbohydrate‐derived 5‐(hydroxymethyl)furfural for the industrial upscaling of 2,5‐diformylfuran

Posted on 9 October 2023 by

In this work, a Ru/Al₂O₃ catalyst was used for the selective oxidation of 5-(hydroxymethyl)furfural to 2,5-diformylfuran achieving excellent yields under mild reaction conditions. Very good catalyst reusability was obtained with an optimized washing method and the scale-up of the oxidation process was investigated.

Abstract

Selective oxidation of 5-(hydroxymethyl)furfural (HMF) to 2,5-diformylfuran (DFF) is an important approach for biobased compound valorization through biorefinery. As there is no large-scale process for this application yet, it is of high importance to find a suitable catalyst system for the production of DFF. In this work, we show that an important step in this direction was taken with a 5 % Ru/Al₂O₃ catalyst, whereby essentially quantitative selectivities could be obtained in the solvent toluene without the significant formation of over-oxidation products. A design of experiments approach was used to determine important information about the main process parameters – catalyst amount, oxygen pressure and reaction temperature. By developing an optimised washing method, excellent results were achieved in terms of catalyst reusability, with HMF conversions of over 99.5 % without loss of the catalyst‘s high selectivity after five cycles. Upscaling experiments were performed with the catalyst in a 5-L reactor at different reactor fill rates, where complete conversion of HMF to DFF was achieved, with a 25 % longer reaction time to achieve full conversion compared to a smaller scale reactor setup.

An Efficient and Recyclable Acid Catalyst (PolyE‐IL) for Production of Pectin from Citrus Peel Waste

Posted on 9 October 2023 by nPragya Singh, nAyush Vasishta, nHitesh S. Pawarn

The manuscript focuses on the valorisation of citrus fruit waste for production of pectin using PolyE-IL-1 catalyst. The catalyst offers several advantages, including high yield, easy catalyst separation, and recyclability. The intensified process provides 30 % pectin yield at a temperature of 95 °C within 90 minutes in a batch mode of operation. Thus, the present process has implications for waste reduction and the production of valuable products from citrus waste by-products.

Abstract

Citrus fruit waste is a potential source for valorisation into pectin. In present manuscript a PolyE-IL-1 as an efficient acid catalyst has been integrated for fractionation of pectin from citrus fruit waste. The use of PolyE-IL-1 catalyst has specific advantages in term of high yield, ease of catalyst separation, recycle and reuse etc. The process optimization study was conducted to check the influence of catalyst concentration, temperature, time and substrate concentration etc., to obtain maximum yield of pectin. The intensified process yields 30 % pectin at 95 °C in 90 min in batch mode of operation. Moreover, batch reactor, ultrasound batch reactor and microwave batch reactor were compared to observe the influence of the mode of reactor operation. Various citrus waste feedstock (Orange, Sweet lime and Lemon) was tested and maximum yield of (32.52 %) pectin was obtained from Lemon peels. The catalyst recyclability study showed consistency in pectin yield (30 %) for five consecutive recycle runs. Thus, the use of an easily recyclable PolyE-IL-1 catalyst provides an efficient route to produce pectin from citrus fruit peel waste.

N‐(4‐Chloromethylbenzyl)‐N, N‐dimethyldodecan‐1‐aminium Chloride: A Quaternary Ammonium Surfactant as Corrosion Inhibitor

Posted on 9 October 2023 by

• A novel N-(4-Chloromethylbenzyl)-N, N-dimethyldodecan-1-aminium chloride (CMBDAC) surfactant was evaluated as a corrosion inhibitor for C1018 CS in a 15% HCl. • CMBDAC displays an outstanding inhibitory efficiency of 99.3% at 50 ppm concentrations in 15% HCl. • CMBDAC can be used as a high-temperature corrosion inhibitor

Abstract

This study used a quaternary surfactant, N-(4-Chloromethylbenzyl)-N, N-dimethyldodecan-1-aminium chloride (CMBDAC), as an excellent corrosion inhibitor of C1018 carbon steel (C1018 CS) in harsh 15 % HCl acidizing condition. CMBDAC was synthesized with an excellent yield and characterized by NMR, FTIR, and TGA. Gravimetric weight loss (WL), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) studies were employed to measure the efficacy of CMBDAC. At a relatively low concentration of 15 ppm, CMBDAC surpassed 90 % inhibition efficiency, with a maximum inhibition efficiency of 99.25 % being reached just for 50 ppm of CMBDAC. The inhibitor showed an efficacy of 96.16 % even at a temperature of 60 °C via the WL technique, showing potential to be used as a high-temperature corrosion inhibitor. The adsorption isotherm study revealed that CMBDAC followed Langmuir adsorption isotherm. The Gibbs free energy of adsorption ( was calculated to be −40.43 kJ mol⁻¹, indicating that CMBDAC was adsorbed via chemisorption. A very high value (1.68×10⁵ L mol⁻¹) of equilibrium constant ( ) suggested very strong adsorption of the inhibitor. PDP study disclosed that CMBDAC acted as a mixed-type inhibitor. SEM-EDX study demonstrated the adsorption of CMBDAC on the C1018 surface. Different DFT-optimized parameters have been discussed in detail to support the superb inhibitory action indicated by CMBDAC.