Nanao/organocatalyat SiO2/4-(2-Aminoethyl)-morpholine as a new, reusable, and efficacious catalyst for the synthesis of polyhydroquinolines derivatives and antibacterially active evaluation

In this study, a new nanocomposite comprising 4-(2-Aminoethyl)-morpholine, an organic catalyst, was prepared on the surface of silica. The absence of metal in the catalyst structure contributes to its environmental friendliness. This novel nanocatalyst was used for multi-component reactions (MCRs). Having a nano size for the composite enhances the contact between the raw materials and the catalytic surface, leading to significant advancement in the reaction. The synthesized composite was identified and evaluated using FT-IR, EDX, EDX-Mapping, TGA, XRD, BET, TEM, and FE-SEM analysis. The characteristic analysis confirmed the synthesis of both nano-silica/4-(2-Aminoethyl)-morpholine catalyst and polyhydroquinoline. The composite's catalytic properties for synthesizing some polyhydroquinoline derivatives were investigated, yielding promising and remarkable results with high 95% yields and short reaction times. The antibacterial properties of the synthesized compounds were also examined against four types of pathogenic bacteria. The highest inhibitory effect was attributed to the compound Ethyl-4-(3-hydroxyphenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate exhibited the highest antibacterial properties.

β-Cyclodextrin Catalyzed, One-Pot Multicomponent Synthesis and Antimicrobial Potential of N-Aminopolyhydroquinoline Derivatives

In the present report, we have described the synthesis of N-aminopolyhydroquinoline (N-PHQ) derivatives using highly efficient β-cyclodextrin (β-CD) as a catalyst by the Hantzsch condensation of substituted aromatic aldehydes, dimedone, and hydrazine hydrate in one pot. The reactions were completed in a shorter time without the generation of any other byproduct. The synthesized N-PHQs were washed thoroughly with distilled water and recrystallized with ethanol to get highly purified products (as crystals). The structure of the synthesized N-PHQs was established by using advanced spectroscopic techniques like FT-IR, NMR (1H, 13C, DEPT, COSY, and HSQC), ESI-MS, and Elemental Analyzer. The N-PHQs derivatives demonstrated moderate to excellent resistance against the tested strains (both fungal as well as bacterial). The presence of polar groups, which are able to form H-bonds, attached to the phenyl ring like -NO2 (4b and 4c), and -OMe (4i, 4j, and 4k) exhibits excellent activity, which is comparable to standard drugs, amoxicillin and fluconazole.

Magnetic curcumin-copper graphene oxide as facile and recyclable heterogeneous nanocatalyst for preparation of polyhydroquinolines and sulfoxides

In this research project, a versatile procedure has been designed for the preparation of supported copper@curcumin on magnetic graphene oxide nanoparticles (GO@Fe3O4@Cur-Cu). The structure of prepared nanocatalyst was characterized by several techniques including; Fourier transform infrared, powder X-ray diffraction, thermal gravimetric analysis, energy dispersive X-ray analysis, inductively coupled plasma optical emission spectroscopy, vibrating sample magnetometer, transmission electron microscopy, and scanning electron microscopy analyses. The catalytic properties of GO@Fe3O4@Cur-Cu were examined for the efficient synthesis of polyhydroquinolines as well as the preparation of sulfoxides through selective oxidation of sulfides in the presence of hydrogen peroxide.

Ionic liquid immobilized on modified magnetic FSM-16: an efficient and magnetically recoverable nanocatalyst

In the present article, a nanocomposite was prepared by immobilizing ionic liquid on the magnetic mesoporous FSM-16 with a core-shell structure (Fe3O4@FSM-16-SO3/IL). Subsequently, the structural properties of the synthesized nanocatalyst were characterized and analyzed by various techniques such as XRD, FT-IR, TEM, FE-SEM, BET, VSM, TGA, and EDS. Fe3O4@FSM-16-SO3/IL was used as a recoverable and efficient nanocatalyst for the synthesis of polyhydroquinoline derivatives. The magnetic nanocatalyst showed remarkable stability and reusability and was reused six consecutive times without considerable loss of its activity.

Fabrication and characterization of a novel catalyst based on modified zirconium metal-organic-framework for synthesis of polyhydroquinolines

A novel catalyst was fabricated in this study based on zirconium MOF modified with pyridine carboxaldehyde in a solvothermal reaction, embedded with cerium. In order to confirm the catalyst structure, various characterization techniques, including FTIR, Far IR, EDX, XRD, TGA, FE-SEM, ICP, and BET analyses, were employed. The results indicated that the UiO-66-Pyca-Ce (III) catalyst had a Langmuir surface area of 501.63 m2/g, a pore volume of 0.28 cm3/g, and a pore size of 2.27 nm. To study catalytic activity, a sequential approach of Knoevenagel condensation and Michael addition was used to synthesize various polyhydroquinoline derivatives. The reaction took place at ambient temperature. The UiO-66-Pyca-Ce (III) catalyst demonstrated high efficacy (90%) and reusability in asymmetric synthesis of polyhydroquinoline derivatives for several reasons, including the possession of three Lewis acid activation functions.

New magnetic nanocomposite Fe3O4@Saponin/Cu(II) as an effective recyclable catalyst for the synthesis of aminoalkylnaphthols via Betti reaction

In this research, a new magnetic nanocomposite Fe₃O₄@Saponin/Cu(II) based on quillaja saponin was prepared and the catalyst structure was characterized thoroughly using FT-IR, EDS, TGA, XRD, VSM, HR-TEM, SEM, ICP, BET analyzes. The catalyst prepared in the three-component synthesis of several Betti bases, 1-(α-aminoalkyl)naphthols, under environmentally friendly conditions was used. The advantage of this reaction is the high efficiency of the products and the short reaction time. Furthermore, Fe₃O₄@Saponin/Cu(II) nano-catalyst is recoverable magnetically and is reusable for other processes with no reduction in its activity.

Transformation of Waste Toner Powder into Valuable Fe2O3 Nanoparticles for the Preparation of Recyclable Co(II)-NH2-SiO2@Fe2O3 and Its Applications in the Synthesis of Polyhydroquinoline and Quinazoline Derivatives

Ecological recycling of waste materials by converting them into valuable nanomaterials can be considered a great opportunity for management and fortification of the environment. This article deals with the environment-friendly synthesis of Fe₂O₃ nanoparticles (composed of α-Fe₂O₃ and γ-Fe₂O₃) using waste toner powder (WTP) via calcination. Fe₂O₃ nanoparticles were then coated with silica using TEOS, functionalized with silane (APTMS), and immobilized with Co(II) to get the desired biocompatible and cost-effective catalyst, i.e., Co(II)-NH₂-SiO₂@Fe₂O₃. The structural features in terms of evaluation of morphology, particle size, presence of functional groups, polycrystallinity, and metal content over the surface were determined by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (P-XRD), field emission gun-scanning electron microscopy (FEG-SEM), energy-dispersive X-ray analysis (EDX), high resolution-transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), Brunauer-Emmett-Teller (BET) analysis, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) studies. XPS confirmed the (II) oxidation state of Co, and ICP-AES and EDX supported the loading of Co(II) over the surface of the support. P-XRD proved the polycrystalline nature of the Fe₂O₃ core and even after functionalization. In comparison to previously reported methods, Co(II)-NH₂-SiO₂@Fe₂O₃ provides an eco-friendly procedure for the synthesis of polyhydroquinoline and quinazoline derivatives with several advantages such as a short reaction time and high yield. Polyhydroquinoline and quinazoline derivatives are important scaffolds in pharmacologically active compounds. Moreover, the developed nanocatalyst was recyclable, and HR-TEM and P-XRD confirmed the agglomeration in the recycled catalyst resulted in a decrease in yield after the fifth run. The present protocol provides a new strategy of recycling e-waste into a heterogeneous nanocatalyst for the synthesis of heterocycles via multicomponent reactions. This made the synthesized catalyst convincingly more superior to other previously reported catalysts for organic transformations.

High-Power and High-Performance Catalyst for Suzuki Coupling Reaction

In this project, the aim was to carry out the Suzuki reaction using a new and unique catalyst with a base of Fe3O4 magnetic nanoparticles coated using a new ligand. In fact, this magnetic catalyst has an inhomogeneous surface to create a connection between the organic and aqueous phases so that the carbon–carbon coupling reaction is completely performed on its large surface. The structure of this catalyst uses two metals, nickel and cobalt, which are coated on a bed of amino linkers and propel the Suzuki coupling reaction at high speed on the catalyst surface. The products obtained are from ideal and optimal conditions with an efficiency of over 98%. The catalyst has a recovery power of over 96% and has enough power to perform several coupling reactions several times. Lastly, the magnetic nanocatalyst is easily separated from the reaction medium by an external field and has 100% power when performing other reactions.

Full Kinetics and Mechanism Investigation for Generating 4-Substituted 1, 4- Dihydropyridine Derivatives in the Presence of Green Catalyst and Aqueous Medium: Experimental Procedure

AIMS AND OBJECTIVE

The main objective of the kinetic investigation of the reaction between ethyl acetoacetate 1, ammoniumacetat 2, dimedone 3, and diverse substitutions of benzaldehyde 4-X, (X= H, NO₂, CN, CF₃, Cl, CH (CH₃)₂, CH₃, OCH₃, OCH₃, and OH) for generating 4-substituted 1, 4-dihydropyridine derivatives (product 5) was to recognize the most realistic reaction mechanism. The layout of the reaction mechanism was studied kinetically via a UV-visible spectrophotometry approach.

MATERIALS AND METHODS

Among the various mechanisms, only mechanism1 (path1) involving 12 steps was recognized as a dominant mechanism (path₁). Herein, the reactions between 1 and 2 (k_obs= 814.04 M^-1.min^-1) and also between 3 and 4-H (k_obs= 151.18 M^-1.min^-1) can be accepted as the first and second steps (step₁ and step₂) of the reaction mechanism, respectively. Amongst all steps, only step9 of the dominant mechanism (path₁) comprised substituent groups (X) near the reaction center.

RESULTS AND DISCUSSION

Para electron-withdrawing or donating groups on the compound 4-X increased the rate of the reaction 4 times more or decreased 8.7 times less than the benzaldehyde alone. So, this step is sensitive for monitoring any small or huge changes in the reaction rate. Accordingly, step9 is the rate-determining step of the reaction mechanism (path₁).

CONCLUSION

The recent result is in agreement with the Hammett description of an excellent dual substituent factor (r = 0.990) and positive value of reaction constant (ρ= +0.9502), which confirms that both the resonance and inductive effects "altogether" contribute to the reaction center of step9 in the dominant mechanism (path₁).

Synthesis, characterization and cytotoxicity evaluation of a novel magnetic nanocomposite with iron oxide deposited on cellulose nanofibers with nickel (Fe3O4@NFC@ONSM-Ni)

A heterogeneous, magnetically recoverable nanocomposite, Fe3O4@NFC@ONSM-Ni(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@NFC@ONSM-Ni(ii) nanoparticles on the in vitro proliferation 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.

Magnetization of biochar nanoparticles as a novel support for fabrication of organo nickel as a selective, reusable and magnetic nanocatalyst in organic reactions

Waste recycling is important process in green chemistry and economic efficiency. Herein, magnetized biochar nanoparticles were modified under green and environmentally friendly method and further were applied as reusable catalyst in organic reactions.

Preparation of a magnetic and recyclable superparamagnetic silica support with a boronic acid group for immobilizing Pd catalysts and its applications in Suzuki reactions

A novel, high activity and magnetic nanoparticles (Fe3O4@SiO2-APBA-Pd) catalyst was prepared. It is 8–15 nm with 0.2–0.6 nm Pd particles. It can be reused 7 runs and catalyze 14 kinds of Suzuki reactions.

A pH-responsive citric-acid/α-cyclodextrin-functionalized Fe3O4 nanoparticles as a nanocarrier for quercetin: An experimental and DFT study

Developing new nanocarriers and understanding the interactions between the drug and host molecules in the nanocarrier at the molecular level is of importance for future of nanomedicine. In this work, we synthesized and characterized a series of iron oxide nanoparticles (IONPs) functionalized with different organic molecules (citric acid, α-cyclodextrin, and citric acid/α-cyclodextrin composite). It was found that incorporation of citric acid into the α-cyclodextrin had negligible effect on the adsorption efficiency (<5%) of citric acid/α-cyclodextrin functionalized IONPs, while the isotherm adsorption data were well described by the Langmuir isotherm model (q_max = 2.92 mg/g at T = 25 °C and pH = 7). In addition, the developed nanocarrier showed pH-responsive behavior for releasing the quercetin molecules as drug model, where the Korsmeyer-Peppas model could describe the release profile with Fickian diffusion (n < 0.45 for at all pH and temperatures). Then, Density functional theory was applied to calculate the absolute binding energies (ΔE_b) of the complexation of quercetin with different host molecules in the developed nanocarriers. The calculated energies are as follow: 1) quercetin and citric acid: ΔE_b = -16.58 kcal/mol, 2) quercetin and α-cyclodextrin: ΔE_b = -46.98 kcal/mol, and 3) quercetin and citric acid/α-cyclodextrin composite: ΔE_b = -40.15 kcal/mol. It was found that quercetin tends to interact with all hosts via formation of hydrogen bonds and van der Waals interactions. Finally, the cytotoxicity of the as-developed nanocarriers was evaluated using MTT assay and both normal NIH-3T3 and cancereous HeLa cells. The cell viability results showed that the quercetin could be delivered effectively to the HeLa cells due to the acidic environment inside the cells with minimum effect on the viability of NIH-3T3 cells. These results might open a new window to design of stimuli-responsive nanocarriers for drug delivery applications.

Emerging Trends in the Syntheses of Heterocycles Using Graphene-based Carbocatalysts: An Update

Graphene-based carbocatalysts owing to numerous amazing properties such as large specific surface area, high intrinsic mobility, excellent thermal and electrical conductivities, chemical stability, ease of functionalization, simple method of preparation, effortless recovery and recyclability have gained a superior position amongst the conventional homogeneous and heterogeneous catalysts. In this review, an endeavor has been made to highlight the syntheses of diverse heterocyclic compounds catalyzed by graphene-based catalysts. Further, the study also reveals that all the catalysts could be reused several times without significant loss in their catalytic activity. Additionally, most of the reactions catalyzed by graphene-based carbocatalysts were carried out at ambient temperature and under solvent-free conditions. Thus, the graphene-based catalysts do not merely act as efficient catalysts but also serve as sustainable, green catalysts. This review is divided into various sub-sections, each of which comprehensively describes the preparation of a particular heterocyclic scaffold catalyzed by graphene-derived carbocatalyst in addition to synthesis of graphene oxide and reduced graphene oxide, functionalization, and structural features governing their catalytic properties. Synthesis of heterocycles catalyzed by graphene-based carbocatalysts.

An efficient clean methodology for the C–S coupling to aryl thioethers and S–S homocoupling to aromatic disulfides catalyzed over a Ce(iv)-leucine complex immobilized on mesoporous MCM-41

Anchored Ce(iv) on the surface of MCM-41 mesoporous silica was used for the synthesis of aryl thioethers and aromatic disulfides.