Ti-based MOFs with acetic acid pendings as an efficient catalyst in the preparation of new spiropyrans with biological moieties

The strategy of designing heterogeneous porous catalysts by a post-modification method is a smart strategy to increase the catalytic power of desired catalysts. Accordingly, in this report, metal-organic frameworks based on titanium with acetic acid pending were designed and synthesized via post-modification method. The structure of the target catalyst has been investigated using different techniques such as FT-IR, XRD, SEM, EDX, Mapping, and N2 adsorption/desorption (BET/the BJH) the correctness of its formation has been proven. The catalytic application of Ti-based MOFs functionalized with acetic acid was evaluated in the preparation of new spiropyrans, and the obtained results show that the catalytic performance is improved by this modification. The strategy of designing heterogeneous porous catalysts through post-modification methods presents a sophisticated approach to enhancing the catalytic efficacy of desired catalysts. In this context, our study focuses on the synthesis and characterization of metal-organic frameworks (MOFs) based on titanium, functionalized with acetic acid pendants, using a post-modification method. Various characterization techniques, including Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), mapping, and N2 adsorption/desorption (BET/BJH), were employed to investigate the structure and composition of the synthesized catalyst. These techniques collectively confirmed the successful formation and structural integrity of the target catalyst. The structure of the synthesized products was confirmed by melting point, 1H-NMR and 13C-NMR and FT-IR techniques. Examining the general process of catalyst synthesis and its catalytic application shows that the mentioned modification is very useful for catalytic purposes. The presented catalyst was used in synthesis of a wide range of biologically active spiropyrans with good yields. The simultaneous presence of several biologically active cores in the synthesized products will highlight the biological properties of these compounds. The present study offers a promising insight into the rational design, synthesis, and application of task-specific porous catalysts, particularly in the context of synthesizing biologically active candidate molecules.

Synthesis and Application of Task-Specific Bimetal-Organic Frameworks in the Synthesis of Biological Active Spiro-Oxindoles

The use of click chemistry as a smart and suitable method for the development of new heterogeneous catalysts is based on metal-organic frameworks as well as the production of organic compounds. The development of the click chemistry method can provide a new strategy to achieve superior properties of MOFs. Here, the two metals Co and Fe are used to create a bimetallic-organic framework. In the following, the click chemistry and postmodification method are well organized and an acidic heterogeneous porous catalyst is developed. This prepared catalyst was used as a highly efficient catalyst for the preparation of new spiro-oxindoles obtained through click chemistry with good to excellent yields (80-94%). This presented catalytic system can compete with the best reported catalytic systems. The findings showed that the presence of Co and Fe metals in the MOF, and the presence of the triazole ring on the catalyst, can increase the catalytic efficiencies. This study offers novel insights into the architecture of Metal-Organic Frameworks (MOFs), click chemistry, and biologically active compounds. Additionally, the research explores the antibacterial properties of the synthesized spiro-oxindoles and catalysts. The findings reveal significant antibacterial activities of the synthesized compounds against S. aureus, MRSA, and E. coli bacteria.

Synthesis of picolinates via a cooperative vinylogous anomeric-based oxidation using UiO-66(Zr)-N(CH2PO3H2)2 as a catalyst

The anomeric effect highlights the significant influence of the functional group and reaction conditions on oxidation-reduction. This article successfully investigates the anomeric effect in the synthesis of picolinate and picolinic acid derivatives through a multi-component reaction involving 2-oxopropanoic acid or ethyl 2-oxopropanoate, ammonium acetate, malononitrile, and various aldehydes. To facilitate this process, we employed UiO-66(Zr)-N(CH₂PO₃H₂)₂ as a novel nanoporous heterogeneous catalyst. The inclusion of phosphorous acid tags on the UiO-66(Zr)-N(CH₂PO₃H₂)₂ offers the potential for synthesizing picolinates at ambient temperature.

Application of Zr-MOFs based copper complex in synthesis of pyrazolo[3, 4-b]pyridine-5-carbonitriles via anomeric-based oxidation

In this research article, Zr-MOFs based copper complex as a novel heterogeneous and porous catalyst was designed and prepared. The structure of catalyst has verified by various techniques such as FT-IR, XRD, SEM, N2 adsorption-desorption isotherms (BET), EDS, SEM-elemental mapping, TG and DTG analysis. UiO-66-NH2/TCT/2-amino-Py@Cu(OAc)2 was used as an efficient catalyst in the synthesis of pyrazolo[3,4-b]pyridine-5-carbonitrile derivatives. The aromatization of titled molecules is performed via a cooperative vinylogous anomeric-based oxidation both under air and inert atmospheres. The unique properties of the presented method are short reaction time, high yield, reusability of catalyst, synthesis of desired product under mild and green condition.

Application of Metal-Organic Frameworks with Sulfonic Acid Tags in the Synthesis of Pyrazolo[3,4-b]pyridines via a Cooperative Vinylogous Anomeric-Based Oxidation

Herein, we report the design and synthesis of Co-MOF-71/imidazole/SO₃H as a novel porous catalyst with sulfonic acid tags. The structure and morphology of the catalyst were investigated using various techniques such as Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction, scanning electron microscopy (SEM), SEM elemental mapping, energy-dispersive X-ray spectroscopy, Barret-Joyner-Halenda, and N₂ adsorption-desorption isotherms. Co-MOF-71/imidazole/SO₃H was studied in the preparation of novel pyrazolo[3,4-b]pyridines under mild and green conditions via a cooperative vinylogous anomeric-based oxidation. A wide range of mono and bis pyrazolo[3,4-b]pyridines were synthesized with good to excellent yields (65-82%). A hot filtration test for the heterogeneous nature of the catalyst indicated the high stability of the prepared catalyst. The recyclability of Co-MOF-71/imidazole/SO₃H is another advantage of the present methodology. The structures of the final products were confirmed using FT-IR, ¹H-NMR, and ¹³C-NMR spectroscopic techniques.

Application of Nanomagnetic Metal-Organic Frameworks in the Green Synthesis of Nicotinonitriles via Cooperative Vinylogous Anomeric-Based Oxidation

In the current study, we synthesized a new nanomagnetic metal-organic framework Fe₃O₄@MIL-53(Al)-N(CH₂PO₃)₂ and characterized it using various techniques. This nanomagnetic metal-organic framework was used for the synthesis of a wide range of nicotinonitrile derivatives as suitable drug candidates by a four-component reaction of 3-oxo-3-phenylpropanenitrile or 3-(4-chlorophenyl)-3-oxopropanenitrile, ammonium acetate (NH₄OAc), acetophenone derivatives, and various aldehydes including those bearing electron-donating, electron-withdrawing, and halogen groups, which afforded desired products (27 samples) via a cooperative vinylogous anomeric-based oxidation (CVABO) mechanism under solvent-free conditions in excellent yields (68-90%) and short reaction times (40-60 min). Increasing the surface-to-volume ratio, easy separation of the catalyst using an external magnet, and high chemical and temperature stability are the advantages of the described nanomagnetic metal-organic frameworks.

Phosphonic acid tagged carbon quantum dots encapsulated in SBA-15 as a novel catalyst for the preparation of N-heterocycles with pyrazolo, barbituric acid and indole moieties

Herein, we have presented a new insight for the synthesis of a hybrid heterogeneous catalyst. For this purpose, phosphonic acid tagged carbon quantum dots of CQDs-N(CH₂PO₃H₂)₂ encapsulated and assembled in channels of SBA-15 using a post-modification strategy. The mesoporous catalyst of functionalized carbon quantum dots (CQDs) was characterized by several techniques. CQDs-N(CH₂PO₃H₂)₂/SBA-15 as an excellent catalyst was applied for the preparation of novel pyrazolo[4',3':5,6]pyrido[2,3-d]pyrimidine derivatives by using pyrazole, barbituric acid and indole moieties at 100 °C under the solvent-free condition. The present work shows that a significant increase in the catalytic activity can be achieved by a rational design of mesoporous SBA-15 modified with CQDs for the synthesis of biological active candidates. The synthesized compounds did not convert to their corresponding pyridines via an anomeric-based oxidation mechanism.

A convenient catalytic method for preparation of new tetrahydropyrido[2,3-d]pyrimidines via a cooperative vinylogous anomeric based oxidation

In this study, a novel functionalized metal-organic frameworks MIL-125(Ti)-N(CH₂PO₃H₂)₂ was designed and synthesized via post-modification methodology. Then, MIL-125(Ti)-N(CH₂PO₃H₂)₂ as a mesoporous catalyst was applied for the synthesis of a wide range of novel tetrahydropyrido[2,3-d]pyrimidines as bioactive candidate compounds by one-pot condensation reaction of 3-(1-methyl-1H-pyrrol-2-yl)-3-oxopropanenitrile, 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione and aromatic aldehydes at 100 °C under solvent-free condition. Interestingly, the preparation of tetrahydropyrido[2,3-d]pyrimidine was achieved via vinylogous anomeric based oxidation mechanism with a high yield and short reaction time.

Catalytic synthesis of new pyrazolo [3,4-b] pyridine via a cooperative vinylogous anomeric-based oxidation

In this study, a novel nano-magnetic metal-organic frameworks based on Fe3O4 namely Fe3O4@MIL-101(Cr)-N(CH2PO3)2 was synthesized and fully characterized. The prepared sample was used as catalyst in the synthesis of pyrazolo [3,4-b] pyridines as convenient medicine by condensation reaction of aldehydes, 5-(1H-Indol-3-yl)- 2H-pyrazol-3-ylamine and 3-(cyanoacetyl)indole via a CVABO. The products were obtained with high yields at 100 °C and under solvent-free conditions.

Magnetic mesocellular foams with nickel complexes: as efficient and reusable nanocatalysts for the synthesis of symmetrical and asymmetrical diaryl chalcogenides

In this work, magnetic mesocellular foam (M-MCF) silica nanoparticles were prepared via inserting magnetic nanoparticles into the pores of mesocellular foams, the inner surface of which was functionalized with a methionine-nickel complex (M-MCF@Met-Ni). The structure of the as-prepared nanocatalysts was studied by FT-IR spectroscopy, BET, TGA, VSM, SEM, HR-TEM, EDS, WDX, XRD, and ICP-OES techniques. Thereafter, this nanocatalyst was used as a new, effective, and magnetically reusable catalyst for C-S and C-Se bond formation under mild conditions. All corresponding products were prepared with good yields and appropriate turnover number (TON) and turnover frequency (TOF), which reveals the high activity of this magnetic nanocatalyst in both reactions. In addition, the recovery and hot filtration tests indicated that this catalyst could be simply separated from the reaction mixture using an outside magnet and reused five consecutive times without any significant loss of its catalyst activity or metal leaching.

Application of novel metal-organic framework [Zr-UiO-66-PDC-SO3H]FeCl4 in the synthesis of dihydrobenzo[g]pyrimido[4,5-b]quinoline derivatives

In the current paper, we produce a new metal-organic framework (MOF) based on Zr metal, [Zr-UiO-66-PDC-SO3H]FeCl4, via an anion exchange method, which is fully characterized by FT-IR, SEM with elemental mapping and EDX, FE-SEM and TEM. Furthermore, the use of [Zr-UiO-66-PDC-SO3H]FeCl4 as a porous catalyst was examined for the one-pot synthesis of novel dihydrobenzo[g]pyrimido[4,5-b]quinoline derivatives by reaction of 6-amino-1,3-dimethylpyrimidine-2,4(1H,3H)-dione, 2-hydroxynaphthalene-1,4-dione and various aldehydes at 100 °C with good to excellent yields.

Applications of novel composite UiO-66-NH2/Melamine with phosphorous acid tags as a porous and efficient catalyst for the preparation of novel spiro-oxindoles

A new approach for the incorporation of phosphorous acid tags into a metal organic framework based on UiO-66-NH2/Melamine was introduced. This new catalyst was applied to the preparation of novel spiro-oxindoles under mild and green conditions.

Anodic electrosynthesis of MIL-53(Al)-N(CH2PO3H2)2 as a mesoporous catalyst for synthesis of novel (N-methyl-pyrrol)-pyrazolo[3,4-b]pyridines via a cooperative vinylogous anomeric based oxidation

In this paper, the MIL-53(Al)-NH2 metal-organic frameworks (MOFs) was prepared based on the anodic electrosynthesis under green conditions. The anodic electrosynthesis as an environmentally friendly procedure was performed in the aqueous solution, room temperature, atmospheric pressure, and in the short reaction time (30 min). Also, the employed procedure was accomplished without the need for the ex-situ salt and base/probase additives as cation source and ligand activating agent at the constant current mode (10.0 mA cm-2). The electrosynthesized MOFs was functionalized with phosphorus acid tags as a novel mesoporous catalyst. This mesoporous catalyst was successfully employed for synthesis of new series (N-methyl-pyrrol)-pyrazolo[3,4-b]pyridines by one-pot condensation reaction of 3-methyl-1-phenyl-1H-pyrazol-5-amine, 3-(1-methyl-1H-pyrrol-2-yl)-3-oxopropanenitrile and various aromatic aldehydes (mono, bis and tripodal). This catalyst proceeded the organic synthetic reaction via a cooperative vinylogous anomeric based oxidation mechanism with a marginal decreasing its catalytic activity after recycling and reusability.

Novel nano-architectured carbon quantum dots (CQDs) with phosphorous acid tags as an efficient catalyst for the synthesis of multisubstituted 4H-pyran with indole moieties under mild conditions

In this work, a new nano-structured catalyst with phosphorus acid moieties, synthesized by the reaction of carbon quantum dots (CQDs) and phosphorus acid under refluxing EtOH. The structure and morphology of CQDs–N(CH₂PO₃H₂)₂ were fully characterized using various techniques such as Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, thermogravimetric (TG) analysis, fluorescence and X-ray diffraction (XRD) measurements. The new CQDs–N(CH₂PO₃H₂)₂ catalyst was successfully used for the synthesis of 2-amino-6-(2-methyl-1H-indol-3-yl)-4-phenyl-4H-pyran-3,5-dicarbonitriles by the one-pot reaction of various aromatic aldehydes, 3-(1H-indol-3-yl)-3-oxopropanenitrile derivatives and malononitrile in refluxing EtOH and/or ultrasonic irradiation conditions.

A new nano-structured catalyst with phosphorus acid moieties, synthesized by the reaction of carbon quantum dots (CQDs) and phosphorus acid under refluxing EtOH.

Spirocyclic derivatives as antioxidants: a review

In recent years, spiro compounds have attracted significant interest in medicinal chemistry due to their numerous biological activities attributed primarily to their versatility and structural similarity to important pharmacophore centers. Currently, the development of drugs with potential antioxidant activities is of great importance since numerous investigations have shown that oxidative stress is involved in the development and progression of numerous diseases such as cancer, senile cataracts, kidney failure, diabetes, high blood pressure, cirrhosis, and neurodegenerative diseases, among others. This article provides an overview of the synthesis and various antioxidant activities found in naturally occurring and synthetic spiro compounds. Among the antioxidant activities reviewed are DPPH, ABTS, FRAP, anti-LPO, superoxide, xanthine oxidase, peroxide, hydroxyl, and nitric oxide tests, among others. Molecules that presented best results for these tests were spiro compounds G14, C12, D41, C18, C15, D5, D11, E1, and C14. In general, most active compounds are characterized for having at least one oxygen atom; an important number of them (around 35%) are phenolic compounds, and in molecules where this functional group was absent, aryl ethers and nitrogen-containing functional groups such as amine and amides could be found. Recent advances in the antioxidant activity profiles of spiro compounds have shown that they have a significant position in discovering drugs with potential antioxidant activities.

Application of novel nanomagnetic metal-organic frameworks as a catalyst for the synthesis of new pyridines and 1,4-dihydropyridines via a cooperative vinylogous anomeric based oxidation

Herein, a new magnetic metal-organic frameworks based on Fe3O4 (NMMOFs) with porous and high surface area materials were synthesized. Then, NMMOFs were characterized by FT-IR, XRD, SEM, elemental mapping, energy dispersive X-ray (EDS), TG, DTG, VSM, and N2 adsorption-desorption isotherms (BET). Fe3O4@Co(BDC)-NH2 as a magnetic porous catalyst was applied for synthesis of novel fused pyridines and 1,4-dihydropyridines with pyrazole and pyrimidine moieties as suitable drug candidates under ultrasonic irradiation. The significant advantages of the presented methodology are mild, facile workup, high yields, short reaction times, high thermal stability, and reusability of the described NMMOFs catalyst.

A straightforward, environmentally beneficial synthesis of spiro[diindeno[1,2-b:2',1'-e]pyridine-11,3'-indoline]-2',10,12-triones mediated by a nano-ordered reusable catalyst

A library of new spiro[diindeno[1,2-b:2',1'-e]pyridine-11,3'-indoline]-2',10,12-trione derivatives has been prepared in an efficient, one-pot pseudo four-component method mediated by a reusable heterogeneous nano-ordered mesoporous SO3H functionalized-silica (MCM-41-SO3H) catalyst. Excellent yields, short reaction times, as well as convenient non-chromatographic purification of the products and environmental benefits such as green and metal-free conditions constitute the main advantages of the developed synthetic methodology. The obtained fused indole-indenone dyes would be of interest to pharmaceutical and medicinal chemistry. Furthermore, due to their sensitivity to pH changes, they could be used as novel pH indicators.

Application of [PVI-SO3H]NO3 as a novel polymeric nitrating agent with ionic tags in preparation of high-energetic materials

In this paper, poly(vinyl imidazole) sulfonic acid nitrate [PVI-SO3H]NO3 was synthesized and fully characterized. Then, [PVI-SO3H]NO3 was applied for the preparation of energetic materials such as 1,1-diamino-2,2-dinitroethene (FOX-7), pentaerythritol tetranitrate (PETN), 1,3,5-trinitro-1,3,5-triazinane (RDX) and trinitrotoluene (TNT). The major advantages of the presented methodology are mild, facile workup, high yields and short reaction times. [PVI-SO3H]NO3 is a suitable nitrating agent for in situ generation of NO2 and without using any co-catalysts of the described nitrating reagent.

Synthesis of biological based hennotannic acid-based salts over porous bismuth coordination polymer with phosphorous acid tags

In this paper, a novel porous polymer capable of coordinating to bismuth (PCPs-Bi) was synthesized. The Bi-PCPs was then reacted with phosphorous acid to produce a novel polymer PCPs(Bi)N(CH2PO3H2)2 which is shown to act as an efficient and recyclable catalyst. The mentioned catalyst was applied for the efficient synthesis of new mono and bis naphthoquinone-based salts of piperidine and/or piperazine via the reaction of hennotannic acid with various aldehydes, piperidine and/or piperazine, respectively. The structure of the resulting mono and bis substituted piperazine or piperidine-based naphthoquinone salts was thoroughly characterized spectroscopically. The electrochemical behavior of the products was also investigated. The presented protocol has the advantages of excellent yields (82-95%), short reaction times (4-30 min) and simple work-up.

Synthesis of Metal-Organic Frameworks MIL-101(Cr)-NH2 Containing Phosphorous Acid Functional Groups: Application for the Synthesis of N-Amino-2-pyridone and Pyrano [2,3-c]pyrazole Derivatives via a Cooperative Vinylogous Anomeric-Based Oxidation

In the current paper, we successfully developed and used metal-organic frameworks (MOFs) based on MIL-101(Cr)-NH2 with phosphorus acid functional groups MIL-101(Cr)-N(CH2PO3H2)2. The synthesized metal-organic frameworks (MOFs) as a multi-functional heterogeneous and nanoporous catalyst were used for the synthesis of N-amino-2-pyridone and pyrano [2,3-c]pyrazole derivatives via reaction of ethyl cyanoacetate or ethyl acetoacetate, hydrazine hydrate, malononitrile, and various aldehydes. The final step of the reaction mechanism was preceded by a cooperative vinylogous anomeric-based oxidation. Recycle and reusability of the described catalyst MIL-101(Cr)-N(CH2PO3H2)2 were also investigated.

Mesoporous Ionically Tagged Cross-Linked Poly(vinyl imidazole)s as Novel and Reusable Catalysts for the Preparation of N-Heterocycle Spiropyrans

Herein, two novel mesoporous cross-linked poly(vinyl imidazole)s with sulfonic acid tags, [PVI-SO3H]Cl (1) and [PVI-SO3H]FeCl4 (2), were prepared and characterized by a variety of techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, elemental mapping, energy dispersive X-ray analysis, transmission electron microscopy, thermal gravimetry, derivative thermal gravimetry, and N2 adsorption-desorption isotherms (Brunauer-Emmett-Teller). In addition, magnetic properties of poly(vinyl imidazole) sulfonic acid iron(IV) chloride [PVI-SO3H]FeCl4 (2) as an ionically tagged magnetic polymer were investigated using a vibrating sample magnetometer. The presented polymers, [PVI-SO3H]Cl (1) and [PVI-SO3H]FeCl4 (2), were successfully applied as reusable and efficient catalysts for the preparation of N-heterocycle spiropyrans. The described catalysts were recycled and reused with a marginal decrease in their catalytic activities. The desired products were prepared under mild and green conditions. The structures of the obtained products were confirmed by various analysis techniques.

Design, Synthesis, and Biological Evaluation of Novel Fused Spiro-4H-Pyran Derivatives as Bacterial Biofilm Disruptor

This study aims to synthesize novel fused spiro-4H-pyran derivatives under green conditions to develop agents having antimicrobial activity. The synthesized compounds were initially screened for in vitro antibacterial activity against two Gram-positive and three Gram-negative bacterial strains, and all the compounds exhibited moderate to potent antibacterial activity. However, compound 4l showed significant inhibition toward all the bacterial strains, particularly against Streptococcus pneumoniae and Escherichia coli with minimum inhibitory concentration values of 125 μg/mL for each. The toxicity studies of selected compounds (4c, 4e, 4l, and 4m) using human red blood cells as well as human embryonic kidney (HEK-293) cells showed nontoxic behavior at desired concentration. Growth kinetic and time-kill curve studies of 4l against S. pneumoniae and E. coli supported its bactericidal nature. Interestingly, compound 4l showed a synergistic effect when used in combination with ciprofloxacin against selected strains. Biofilm formation in the presence of a lead compound, as assessed by XTT assay, showed complete disruption of the bacterial biofilm visualized by scanning electron microscopy. Overall, the findings suggest 4l to be considered as a promising lead for further development as an antibacterial agent.

Magnetic MCM-41 nanoparticles as a support for the immobilization of a palladium organometallic catalyst and its application in C–C coupling reactions

An organometallic catalyst of palladium has been immobilized on magnetic MCM-41 nanoparticles and used for C–C coupling reactions. The products were obtained in high yields and good TOF values which were indicate the high efficiency of this catalyst.