New Acetamidine Cu(II) Schiff base complex supported on magnetic nanoparticles pectin for the synthesis of triazoles using click chemistry

MIL-88-NH2(Fe) conjugated pectin through a post-modification Ugi four-component reaction: A robust bio-based catalyst for the synthesis of cyclic carbonate via CO2 fixation reaction

The functionalization of materials via multicomponent reactions (MCRs) led to a recent surge in the interest of researchers, owing to the creation of exceptional properties in materials. Herein, a novel robust porous catalyst was prepared via the conjugation of MIL-88-NH2(Fe) and pectin (DAP/MIL-88-NH2(Fe)) through the post-modification Ugi four-component reaction (Ugi-4CR) for the first time. To achieve this aim, pectin was oxidized using sodium periodate as an oxidant agent to produce dialdehyde pectin (DAP). Next, the generated carbonyl functional groups participated in the Ugi-4CR of MIL-88-NH2(Fe), 4-methyl carboxylic acid, and cyclohexyl (c-hex) isocyanide to produce DAP/MIL-88-NH2(Fe) catalyst. The catalytic activity of the prepared bio-based catalyst was examined in producing cyclic carbonates through the chemical fixation of CO2 with epoxides in the presence of TBAB as a co-catalyst. Interestingly, catalytic experiments revealed that the prepared bio-based catalyst could be remarkably active regarding the CO2 fixation reaction and performed it in the shortest reaction time (1 h) via high CO2 adsorbent capacity. The outstanding benefits of the prepared bio-based catalyst include its non-hazardous nature, inexpensive, green and gentle reaction conditions, and ability to be reusable in several runs with slight loss of catalytic activity due to a more durable framework with high chemical and thermal stability.

Copper (II) complex supported on magnetic nanoparticles as a novel nanocatalyst for the synthesis of imidazo[1,2-a]pyridines

Research on the synthesis of imidazo[1,2-a]pyridines has gained great importance among synthetic chemists because there have been numerous reports of their biological and medicinal activities. In this respect, we fabricated CuCl2 immobilized on Fe3O4 nanoparticles modified with 1,10-phenanthroline-5,6-diol [Fe3O4@Diol/Phen-CuCl2] and investigated its catalytic activity for the preparation of imidazo[1,2-a]pyridine derivatives through one-pot three-component reaction of 2-aminopyridines, aldehydes and terminal alkynes under ecofriendly conditions. FT-IR spectroscopy, EDX, SEM, TEM, XRD, TGA, VSM and ICP-OES techniques employed in order to identify the structure of the as-constructed Fe3O4@Diol/Phen-CuCl2 nanocatalyst. This catalytic system has a series of advantages such as the synthesis of imidazo[1,2-a]pyridine products with high yields in suitable time, performing the reactions in an environmentally friendly solvent (PEG), easy preparation of the catalyst with a simple method, and the recyclability of the Fe3O4@Diol/Phen-CuCl2 nanocatalyst.

Comparative study of antioxidant and antimicrobial activity of berberine-derived Schiff bases, nitro-berberine and amino-berberine

In recent years, the scientific community has focused on traditional natural products and their potential therapeutic benefits. Berberine is a plant-derived isoquinoline alkaloid with a variety of biological properties and identified as a promising pharmacophore for discovering new therapeutic agents against various diseases. However, unfavorable pharmacokinetic properties of berberine have limited its clinical application so much that researchers pursue its structure modification to overcome this problem. This study focuses on the synthesis of new berberine derivatives to improve its antioxidant and antimicrobial potentials, which were characterized using CHNO and NMR instruments. Berberine extracted from barberry root was nitrated, reduced to amine and condensed with benzaldehyde derivatives to produce berberine-based Schiff bases. The H atom donating ability of all compounds was measured against DPPH free radicals, with IC50 values ranging from 18.28 to 108.20 μg ml-1. All berberine-based Schiff bases exhibited stronger antioxidant activity than nitro-berberine and amino-berberine. Only Schiff base derived from 4-hydroxybenzaldehyde showed slightly better antioxidant effects than original berberine. The inhibitory effects of the synthesized compounds were evaluated against important pathogenic fungal and bacterial strains using disk diffusion assays, with inhibition zone diameters ranging from 8.36 to 25.48 μg ml-1. Berberine itself only affected Candida albicans fungus. Nitrated berberine was effective against all microorganisms except Gram-negative Acinetobacter baumannii. The results suggest that structural modifications and functionalization can enhance the antimicrobial and antioxidant properties of berberine.

Loading of green-synthesized cu nanoparticles on Ag complex containing 1,3,5-triazine Schiff base with enhanced antimicrobial activities

The physicochemical properties of materials change significantly in nanometer dimensions. Therefore, several methods have been proposed for the synthesis of nanoparticles. Plant extracts and essential oils are applied as natural and economic resources to prepare nanomaterials especially metal nanoparticles. In this project, a green, simple and efficient method has been designed for the synthesis of Cu nanoparticles using Purple cabbage extract as a reducing and stabilizing agent. They were successfully loaded onto a new Ag complex containing 1,3,5-triazine Schiff base as ligand to form Cu@Ag-CPX nanocomposite. Phytochemical contents of extract were identified by standard qualitative analyses. The chemical structure of all synthesized compounds was characterized using spectral data. In FT-IR, coordination of C=N bond of Schiff base ligand to Ag+ ions shifted the absorption band from 1641 to 1632 cm-1. The UV-Vis spectrum of Cu@Ag-CPX nanocomposite shown the peak related to Cu nanoparticles in the region of around 251 nm. 5:7 molar ratio of Cu to Ag in Cu@Ag-CPX was determined using ICP-OES. The FESEM, TEM, and DLS techniques provided valuable insights into the morphology and size distribution of the nanocomposite, revealing the presence of rods and monodispersed particles with specific diameter ranges. These analyses of the nanocomposite displayed rods with diameters from 40 to 62 nm as well as monodispersed and uniform particles with average diameter of 45 nm, respectively. The presence of elements including carbon, nitrogen, oxygen, Cu and Ag was proved by EDX-EDS analysis. The XRD pattern of Cu@Ag-CPX shown the diffraction peaks of Cu and Ag particles at 2θ values of 10°-80°, and confirmed its crystalline nature. The inhibitory properties of the synthesized compounds were evaluated in vitro against four Gram-negative and two Gram-positive bacteria, as well as two fungal strains. The MIC, MBC and MFC values obtained from microdilution and streak plate sensitivity tests were ranged from 128 to 4096 µg ml-1. While Cu nanoparticles and Ag complexes were effective against some pathogens, they were not effective against all them. However, the growth of all tested microbial strains was inhibited by Cu@Ag-CPX nanocomposite, and makes it as a new promising antimicrobial agent. Modification of nanocomposite in terms of nanoparticle and complex can improve its blocking activities.

Advances in the greener synthesis of chromopyrimidine derivatives by a multicomponent tandem oxidation process

A hydrophilic cobalt/copper heterogeneous bimetallic catalyst named mTEG-CS-Co/Cu-Schiff-base/IL was successfully synthesized from chitosan polysaccharide. The new catalyst was investigated and confirmed using various techniques including FT-IR, FE-SEM, EDX-EDS, XRD, TEM, TGA, AFM, NMR and ICP. The catalyst exhibited powerful catalyst activity for the tandem one pot oxidative chromopyrimidine reaction from benzyl alcohols under mild conditions, utilizing air as a clean source in a green protocol. The catalyst was compatible with a wide range of benzyl alcohols, and aldehydes formed in situ, and bis-aldehydes synthesized were condensed with urea/4‑hydroxycumarin to provide favorable products in good yields for all derivatives (14 new derivatives). The presence of tri-ethylene glycol and imidazolium moieties with hydrophilic properties on the mTEG-CS-Co/Cu-Schiff-base/IL nanohybrid provides dispersion of the nanohybrid particles in water, leading to higher catalytic performance. Furthermore, the reaction exhibited several other notable features, including low catalyst loading, the ability to be recycled for up to 6 stages, high atom economy, a simple work procedure, short reaction time, utilization of an environmentally friendly nanohybrid, and the replacement of volatile and organic solvents with water solvent.

Strategies for Improving Selectivity and Sensitivity of Schiff Base Fluorescent Chemosensors for Toxic and Heavy Metals

Toxic cations, including heavy metals, pose significant environmental and health risks, necessitating the development of reliable detection methods. This review investigates the techniques and approaches used to strengthen the sensitivity and selectivity of Schiff base fluorescent chemosensors designed specifically to detect toxic and heavy metal cations. The paper explores a range of strategies, including functional group variations, structural modifications, and the integration of nanomaterials or auxiliary receptors, to amplify the efficiency of these chemosensors. By improving selectivity towards targeted cations and achieving heightened sensitivity and detection limits, consequently, these strategies contribute to the advancement of accurate and efficient detection methods while increasing the range of end-use applications. The findings discussed in this review offer valuable insights into the potential of leveraging Schiff base fluorescent chemosensors for the accurate and reliable detection and monitoring of heavy metal cations in various fields, including environmental monitoring, biomedical research, and industrial safety.

Research on the catalytic activity of MNP-[Dop-OH]-CuBr2 nanocomposites: novel and stable reusable nanocatalysts for the synthesis of 1,3,5-triazine derivatives

In recent years, magnetic nanocatalysts have been recommended as one of the best catalysts by chemists. Among magnetic nanoparticles, Fe₃O₄ nanoparticles are highly suitable due to their magnetic properties, chemical stability and low toxicity. These catalysts can be separated via magnetic separation after the chemical process is over and reused after regeneration. Owing to the importance of 1,3,5-triazine derivatives in pharmaceutical and medicinal chemistry, the synthesis of these compounds is always one of the important goals of organic chemists. In this research work, we first successfully synthesized CuBr₂ immobilized on magnetic Fe₃O₄ nanoparticles functionalized with Dop-OH (prepared via the reaction of MNP-dopamine with 2-phenyloxirane) nanocomposites and then investigated their catalytic application in the synthesis of 1,3,5-triazine derivatives via an oxidative coupling reaction of amidine hydrochlorides and alcohols in air. Recycling experiments clearly revealed that MNP-[Dop-OH]-CuBr₂ nanocatalysts could be reused for at least 8 times without much loss of catalytic activity.

TiO2/g-C3N4/SO3H(IL): Unique Usage of Ionic Liquid-Based Sulfonic Acid as an Efficient Photocatalyst for Visible-Light-Driven Preparation of 5-HMF from Cellulose and Glucose

Upgrading of biomass wastes to value-added materials has been incessantly pursued worldwide with diverse applications, especially deploying photocatalytic composites encompassing metal oxides with acidic and carbon compounds. Herein, the fabrication of a morphologically unique acidic catalyst encompassing a two-dimensional (2D) TiO₂/g-C₃N₄ heterojunction feature is described for the generation of 5-hydroxymethylfurfural (5-HMF), which exploits the acidic/ionic liquid (IL) bifunctional photocatalysis under visible light. The structural integrity of the synthesized TiO₂/g-C₃N₄/SO₃H(IL) was corroborated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy-energy-dispersive spectroscopy (EDX-EDS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), UV-vis, Tauc plots, transmission electron microscopy (TEM), and Brunauer-Emmett-Teller-Barrett-Joyner-Halenda (BET-BJH) analyses. Keeping environmental impact in mind, there are compelling advantages in the development of bio-derived pathways to access ILs from natural renewable resources. The outcomes of environmental assessments have revealed that the incorporation of TiO₂ in g-C₃N₄ and ClSO₃H can reduce the probability of recombination due to ionic charges present, therefore enhancing the photocatalytic activity via the transformation of cellulose and glucose to produce 5-HMF in higher yields, with the optimum conditions being reaction in water under a blue light-emitting diode (LED), at 100 °C, for 1-1.5 h. The main advantages of this production method include minimum number of synthetic steps as well as ample availability of and easy access to primary ingredients. While a significant volume of 5-HMF was produced under blue light-emitting diode (LED) radiation, the selectivity was drastically reduced in the dark. The salient attributes of the catalyst comprise stability in air, robustness, reusability, and its overall superior activity that is devoid of hazardous additives or agents. This inimitable method has uncovered a newer strategy for enhancing the photocatalytic attributes of deployed semiconducting materials for numerous photocatalytic functions while adhering to the tenets of environmental friendliness.

Metal Complexes with Schiff Bases: Data Collection and Recent Studies on Biological Activities

Metal complexes play a crucial role in pharmaceutical sciences owing to their wide and significant activities. Schiff bases (SBs) are multifaceted pharmacophores capable of forming chelating complexes with various metals in different oxidation states. Complexes with SBs are extensively studied for their numerous advantages, including low cost and simple synthetic strategies. They have been reported to possess a variety of biological activities, including antimicrobial, anticancer, antioxidant, antimalarial, analgesic, antiviral, antipyretic, and antidiabetic ones. This review summarizes the most recent studies on the antimicrobial and antiproliferative activities of SBs-metal complexes. Moreover, recent studies regarding mononuclear and binuclear complexes with SBs are described, including antioxidant, antidiabetic, antimalarial, antileishmanial, anti-Alzheimer, and catecholase activities.

BioMOF-Mn: An Antimicrobial Agent and an Efficient Nanocatalyst for Domino One-Pot Preparation of Xanthene Derivatives

In this paper, a new Mn-based metal-organic framework [UoB-6] was obtained via a one-step ultrasonic irradiation method with the ligand (H₂bdda: 4,4'-(1,4-phenylenebis(azaneylylidene))bis(methaneylylidene))dibenzoic acid. The structural integrity of the synthesized BioMOF-Mn was corroborated by FT-IR, EDX, ICP, XRD, TEM, DLS, FESEM, and BET-BJH analyses. The aerobic oxidative domino reaction of benzyl alcohols or aldehydes with dimedone derivatives was performed in the presence of the UoB-6 catalyst to produce xanthene derivatives in good yields. Hot filtration and Hg poisoning tests proved the heterogeneous nature of the catalyst. Novel synthesized xanthene-based bis-aldehydes were introduced as potent HDAC1 inhibitors according to molecular docking calculations. Finally, the inhibitory activities of Mn-MOF nanoparticles were evaluated on Escherichia coli and Candida albicans. The MIC, MBC, and MFC values were determined from 2048 to 4096 μg·mL^-1 according to antimicrobial susceptibility testing methods. The inhibitory effects of antimicrobial agents can be exacerbated when loaded on BioMOFs.

Nanomagnetic macrocyclic Schiff-base-Mn(ii) complex: an efficient heterogeneous catalyst for click approach synthesis of novel β-substitued-1,2,3-triazoles

In the present work, a novel symmetrical 15-membered macrocyclic Schiff base complex of manganese was prepared using the reaction of the synthetic 2,6-diacetylpyridine functionalized Fe₃O₄ MNPs with 2,2-(piperazine-1,4-diyl)dianiline and Mn(ii) bromide salt via a template approach. The resulting [Fe₃O₄@PAM-Schiff-base-Mn][ClO₄] heterogenized complex was characterized using FT-IR, XRD, BET, TGA, EDX, Xray-mapping, SEM, TEM and VSM analysis. To demonstrate proof of concept, Huisgen 1,3-dipolar cycloaddition synthesis of 1,2,3-triazoles was selected to evaluate the activity and reusability of the catalyst. The ethanol as a green solvent proved to be an excellent reaction medium for this synthesis. Yields of up to 100% were obtained in some cases. Significantly, as demonstrated, [Fe₃O₄@PAM-Schiff-base-Mn][ClO₄] catalyst was recycled for 8 cycles without losing catalytic activity under the optimized reaction conditions. The hot filtration and ICP-OES tests ratified that there was no leaching of metal during the catalytic reaction, indicating the heterogeneous manner of the catalyst.