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Silver nanoparticles with large surface area and surface available atoms provide promising opportunities to deal with the challenges in catalysis and environmental remediation. Herein, silver nanoparticles impregnated reduced graphene oxide (AgNPs@RGO) is synthesized through the in-situ reduction process using green guava fruit extract as a reducing agent. The synthesized materials are characterized by multiple characterization tools such as FTIR, XRD, UV–Vis, XPS, Raman, FESEM and TEM studies. X-ray photoelectron spectroscopic (XPS) result has confirmed the in-situ reduction of GO and Ag+ ions to RGO and Ago, respectively. Morphological studies like FESEM and TEM have suggested well dispersion of AgNPs onto the RGO sheets. The synthesized material showed improved efficiency for the catalytic reduction of water-pollutant like p-nitrophenol. Here, the catalyst works as a hydrogen transport. The AgNPs@RGO material also showed efficient catalytic activity for terminal alkyne carboxylation up to 98.5% of product yield. The catalyst is reusable for multiple reaction cycles for both the studied reactions.

The present work introduces the favorable synthesis of porous functionalized nanomaterials with excellent surface area, porosity, and high CO2 capture ability to facilitate cyclizative reactions by...

We have described a facile solvothermal synthesis of a sheet-like α-Ti(HPO4)2·H2O nanomaterial. The material comprises 10.7 nm nanoparticles along with ordered mesopores throughout its hexagonal building blocks. The material possesses a bandgap of 3.86 eV and works as an efficient catalyst for the selective synthesis of ureas from a broad range of isocyanates in the presence of H2O at room temperature with a high product yield (up to 93%) and a TOF value up to 15.25 h−1. The α-Ti(HPO4)2·H2O nanomaterial also catalytically converts glucose to levulinic acid (LA) and subsequently LA to alkyl levulinates in the presence of different alcohols with a high product yield (up to 98%) and a TOF value up to 43.00 h−1. Furthermore, all the reactions are performed under green and facile catalytic conditions without using any hazardous solvent. The α-Ti(HPO4)2·H2O catalyst material was also found to be reusable for manifold cycles for all the reactions, keeping its catalytic efficiency along with its structural and morphological characteristics unaffected, supporting its industrial relevance.

Synthesis of cyclic carbonates via CO2 cycloaddition reaction with epoxides is one of the promising strategies to valorize greenhouse gas CO2, thereby fixing it to the value-added chemicals. In this study, uniform copper oxide nanoparticles (Cu2O, Cu4O3) with variable oxidation states are stabilized by functionalized covalent organic frameworks (COF) and effectively utilized as a catalyst for the synthesis of cyclic carbonates under ambient temperature and atmospheric pressure. Characterization techniques e.g. powdered X-ray Diffraction (PXRD), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR) and nitrogen physisorption (BET) coupled with DFT studies predict that the copper oxide nanoparticles are anchored on the mesochannels of covalent organic frameworks through a covalent-coordinate linkage. The catalyst exhibits significantly high turn over numbers (TON, order of 105) and more than 99% selectivity towards synthesis of cyclic carbonates with exceptional recyclability.

Nanotechnology has the impending ability to improve the therapeutic potential of drugs and radiation-based treatment approaches for reducing cancerous cell death while curtailing collateral toxicity to non-cancerous cells. Among all metal nanomaterials, gold nanoparticles (AuNPs) are establishing themselves as an excellent radiosensitizer and serve as a multimodal modality due to their unique physicochemical properties. The primordial purpose of the work is to evaluate the synergistic effect and molecular level interaction of gamma (γ) radiation on human cervical cancer cell (HeLa) in the presence of AuNPs. Biocompatible AuNPs in combination with γ-radiation were found to exhibit elated cytotoxic effects on cancer cells as evidenced by cell-based assays. The implication of AuNPs facilitates the minimization of radiation dose employment on cultured cells. As per our experimental evaluation, the modus operandi of dual effectors ascertained that a higher amount of reactive oxygen species (ROS) plays a key role in cellular functionality collapse. In that scenario, it can be concluded that AuNP-mediated radiosensitization proved to be the plausible candidate for preclinical testing in nanoparticle-based radiotherapy.

A new heterogeneous polymer supported solid phase oxovanadium(IV) catalyst was synthesized successfully. The designed catalyst furnished excellent results in the oxidation reactions of various aromatic alkanes, e.g. toluene, para-xylene, mesitylene. The polymer supported vanadium complex was proved also an efficient catalyst for the oxidation of aromatic alkenes, like substituted styrenes, trans-stilbene, etc. under mild reaction conditions. The supported catalyst was nicely elucidated by SEM-EDAX, TGA, FT-IR and UV–Vis spectral analysis. The catalytic activity was tested in the presence of an environment-friendly oxidant, 30% aqueous H2O2 during the oxidation of broad range of substrates. Another important fact is that the designed oxovanadium(IV) catalyst is heterogeneous in nature. Moreover, the newly synthesized oxovanadium(IV) complex exhibited a notable recoverability and it could be recycled up to six runs devoid of any prominent reduction in catalytic behavior.

Novel polystyrene incorporated Palladium (II) catalyst was developed and well characterized. The efficiency of the supported Pd(II) catalytic material was checked for double carbonylation reaction of 2° amines and aryl iodides to their corresponding α-ketoamides under high pressure reaction conditions. The reaction was carried out in 60 psi carbon monoxide pressure. An extensive variety of aryl iodides in combination with 2° amines in presence of carbon monoxide can produce the respective α-ketoamides with superb chemoselectivity. Effect of solvents, bases, time and amount of catalyst for the production of α-ketoamides were reported. This supported Pd(II)complex was highly catalytically active and recyclable. The developed catalytic material was regenerated by filtration. It could be recycled further six times with no such profound loss in its activity.

Herein, we report the molecular and supramolecular structure, photoluminescence, redox behavior and product selective catalytic activity of [Cu2(oxalate)(1,10-phen)2Cl2] (where 1,10-phen = 1,10-phenanthroline) synthesized by using hydrophilic oxalate as bridging ligand and the hydrophobic 1,10-phen as the blocker ligand. Structural analysis reveals that this binuclear Cu(II)-complex crystallizes in achiral monoclinic P21/n space group and it has a 3D supramolecular structure. Each Cu-center displays five coordinated distorted square pyramidal geometry. Two such Cu centers are connected by oxalato-bridge to form the bi-nuclear-metal core and two 1,10-phen molecules block the outer periphery of the core and restrains further polymerization. These binuclear metallic units are connected by supramolecular hydrogen bonding and π⋯π interactions to form a 3D supramolecular architecture. The complex is stable up to 230 °C. A reversible redox couple centered at (E1/2) ∼ −27 mV with ΔEp ∼ 206 mV corresponding to the CuII/I couple was detected in the cyclic voltammogram of the complex in acetonitrile. The complex shows emission maxima at 451 and 480 nm upon excitation at 340 nm due to π-π* transition in the aromatic π-rings of 1,10-phenanthroline. Density functional analysis has been performed to explore the molecular structure and character of the orbitals within the complex. Due to the presence of five coordinated Cu-centers, the lewis acidic catalytic activity of the complex has been studied. It exhibits selective oxidation behavior for alkenes in presence of several oxidants. It shows 100% selectivity with 70% conversion for the oxidation of cis-cyclooctene to corresponding epoxide at 50 °C in presence of H2O2 as oxidant in acetonitrile.

Chemical fixation of CO2 into the organic molecules is very challenging from the perspective of greenhouse gas consumption and manufacturing of chemicals with C1 backbone. The process was developed with the synthesis of an efficient polystyrene functionalized Magnesium-anthranilic acid complex (Mg@PS-anthra). The catalytic system was successfully explored as a heterogeneous catalyst for the synthesis of cyclic carbonates by CO2 fixation at atmospheric pressure and Knoevenagel condensation reaction under room temperature solvent free condition. The material was thoroughly characterized by diffuse reflectance UV-vis, FTIR spectroscopy, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and powder X-ray diffraction (PXRD) techniques. The catalytic pathway has been investigated for the cyclo-addition reaction of epoxides using atmospheric CO2 accompanied by the Knoevenagel condensation reaction with a variety of different aldehydes over cost effective environmental friendly Mg-catalyst. This is attributed to its high catalytic activity, recovery simplicity and excellent five times recycling efficiency; without any substantial decrease in catalytic performance.

Cu nanoparticles were prepared in an aqueous phase by means of a simple reduction-route using sodium borohydride as the reducing agent in the presence of ascorbic acid and polyvinylpyrrolidone (PVP). The hydrosol of the Cu nanoparticles deteriorated within a day. It compelled to initiate a scheme to stabilize the nanoparticles for a long period of time. Phase transfer to organic solvents using Benzyldimethylstearylammonium chloride (BDSAC) as a phase transfer agent was found to be an effective path in this respect. BDSAC performed the dual role of dragging the Cu nanoparticles from water to organic solvent and also acted as a capping agent along with PVP for better stabilization of Cu nanoparticles. The organosol of the Cu nanoparticles exhibited excellent stability and promising catalytic activity towards N-formylation reactions on a number of amine substrates in presence of visible green LED light. The yield and reusability of the catalyst were promising. All the samples were thoroughly characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, energy dispersive analysis of x-rays, x-ray photoelectron spectroscopy and thermo gravimetric analysis.

We demonstrated the photocatalytic reduction of CO2 to HCOOH using mesoporous SnO2 nanoparticles as active photocatalysts in water, which acted as a sacrificial electron source as well as a solvent under atmospheric pressure. Greater than 114 TON was achieved by using only 10 mg of the catalyst. The reaction did not occur in the absence of light (white LED) and could be readily controlled by light intensity alternation. We also demonstrated that a TON of 25 could be obtained with the use of sunlight using the catalytic cycle. These results open the door to a new class of protocols for the photocatalytic reduction of CO2 using SnO2 nanoparticles under visible light irradiation in green reaction conditions.

Utilization of carbon dioxide in chemical fixation for synthesis of fine chemicals like benzimidazoles, organic carbamates, etc. is in high demand in recent years as carbon dioxide is a cost effective, sustainable, and green renewable C1 source. In this article we present the design and synthesis of an organically modified polystyrene bound heterogeneous [PS-Zn(II)-SALTETA] catalyst. The catalyst has been characterized thoroughly by Fourier transform infrared spectroscopy, atomic absorption spectroscopy, thermo gravimetric analysis, PXRD, SEM and EDAX studies. The catalyst was used for cyclization of o-phenylenediamines through insertion of carbon dioxide in order to produce benzimidazoles in the presence of dimethylamine borane (DMAB). The developed catalytic procedure is sustainable, economical and efficient owing to the utilization of ethanol/water as a biodegradable and environment friendly solvent system. Besides benzimidazole production the catalyst was also very active for manufacture of organic carbamates from anilines and n-butyl bromide under atmospheric CO2 pressure under solvent free conditions at room temperature and the catalytic protocol showed outstanding functional group tolerance. Moreover the catalyst is highly recyclable and reusable.

In this existing work, an efficient polymer-supported palladium catalyst, a furfurylamine-functionalized Merrifield complex of palladium [Pd@(Merf-FA)], was synthesized and characterized, showing excellent catalytic activity towards in situ carbonylation reactions using carbon monoxide surrogates like formic acid and chloroform. Herein, we examined the catalytic activity of the Pd@(Merf-FA) catalyst for the formylation of aryl iodides and carbonylative Suzuki–Miyaura coupling reactions. The Pd@(Merf-FA) catalyst was systematically characterized by several techniques like HRTEM, elemental mapping, PXRD, TGA-DTA, FESEM, UV-vis, EDAX, CHN and AAS analysis. The catalyst is highly recyclable, able to be recycled up to six times without showing any significant decrease in catalytic activity. The [Pd@(Merf-FA)] catalyst proved to be more efficient compared to the corresponding homogeneous palladium catalyst. In addition, the leaching experiment of the synthesized catalyst was studied, which showed that negligible leaching of metal occurred from the polymeric support.

This work represents an efficient and unique phosphine-free approach for the polystyrene embedded Schiff-base palladium catalyzed diaryl urea synthesis and Suzuki-Miyaura cross-coupling reaction by reductive carbonylation process. The careful instrumental investigations with FE-SEM, TEM, EDAX, TGA, UV–Vis, FTIR, AAS, and elemental analysis precisely characterized the developed heterogeneous catalyst. Reaction parameters, like catalytic natures, starting materials, reaction environment, and solvent were examined sequentially. The present work has been adequately addressed to account for the generation and characterization of a new polymer bound Pd-catalyst and using it in the synthesis of diaryl ureas and diaryl ketones, with no substantial decay of catalytic activity.

Chemical fixation of CO2 and synthesis of biofuels through convenient reaction pathways are very demanding in the context of sustainable and eco-friendly catalysis. Herein, we report the synthesis of iron-phosphonate nanoparticles HPFP-1(NP) through the simple chemical reaction between hexamethylenediamine-N,N,N′,N′-tetrakis-(methylphosphonic acid) and FeCl3 under hydrothermal conditions. The material has been characterized by transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), N2 adsorption/desorption studies and FE-SEM. This porous material showed high catalytic activity for the synthesis of organic carbonates from a wide range of epoxides at room temperature in the presence of CO2 at atmospheric pressure. This nanocatalyst also exhibited excellent catalytic activity for the conversion of levulinic acid into alkyl levulinates. The HPFP-1(NP) catalyst showed high recycling efficiency in these catalytic reactions.

Hydrodeoxygenation process is a potential route for upgrading biofuel intermediates, like vanillin, which is obtained in huge quantities through the chemical treatment of the abundant lignocellulosic biomass resources of nature, and this is attracting increasing attentions over the years. Herein, we report the grafting of palladium nanoparticles at the surface of porous organic polymer Pd-PDVTTT-1 synthesized through the co-condensation of 1,3,5-triallyl-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione and divinylbenzene in the presence of radical initiator under solvothermal reaction conditions. The Pd-PDVTTT-1 material has been characterized thoroughly by powder X-ray diffraction, nitrogen sorption, ultra-high-resolution transmission electron Microscopy, Fourier-transform infrared spectroscopy, 13C MAS NMR, and X-ray photoelectron spectroscopy analyses. High surface area together with good thermal stability of the Pd-PDVTTT-1 material has motivated us to explore its potential as heterogeneous catalyst in the hydrodeoxygenation of vanillin for the production of upgraded biofuel 2-methoxy-4-methylphenol in almost quantitative yield and high selectivity (94%).

A mutually correlated green protocol has been devised that originates from a sustainable production of β-Ni(OH)2 nanoparticles which is used for an efficient catalytic synthesis of versatile substituted tetrazoles, under mild reaction conditions in water via a simple, one-pot, eco-friendly method. The synthesis is followed by derivatization into a highly fluorescence active compound 9-(4-(5-(quinolin-2-yl)-1H-tetrazol-1-yl)phenyl)-9H-carbazole that can be used at tracer concentrations (0.1 μM) to detect as well as quantify hydrogen peroxide down to 2 μM concentration. The nanocatalyst was synthesized by a simple, proficient, and cost-effective methodology and characterized thoroughly by UV-vis absorption and Fourier transform infrared spectra, N2 adsorption/desorption, high resolution transmission electron microscopy, powder X-ray diffraction pattern, field emission scanning electron microscopy, and thermogravimetric analysis. Broad substrate scope, easy handling, higher efficiency, low cost, and reusability of the catalyst are some of the important features of this heterogeneous catalytic system. The strong analytical performance of the resultant derivative in low-level quantification of potentially hazardous hydrogen peroxide is the key success of the overall green synthesis procedure reported here.

A polystyrene functionalized Zinc anthranilic acid complex catalyst has been prepared. The PS-Zn-anthra complex has been characterized by EDX, Scanning electron micrographs (FE-SEM), FTIR spectra, UV–vis spectra and thermogravimetric analyses. A greener and novel methodology was considered for the production of dicoumarol derivatives utilizing PS-Zn-anthra complex as a Lewis acid catalyst, non-toxic, mild in H2O employing heteroaromatic/aromatic aldehydes and 4-hydroxycoumarin. The catalyst also shows good catalytic activity in the cyclo addition of CO2 to epoxide. The results of activity of catalyst imply that the procedure adopted provides numerous advantages such as low loading of catalyst, operational simplicity, mild reaction conditions, quantitative yields, and short reaction time. The PS-Zn-anthra complex exhibited the elevated efficiency of recycling in these reactions. This catalyst can be recycled for five times without appreciable loss of its activity.

Chemical fixation of CO2 and synthesis of organic carbamates through phosgene –free eco-friendly pathway using a heterogeneous and sustainable catalyst is always a demanding field in synthesis chemistry. Herein, we presented the design and synthesis of a polymer support sustainable heterogeneous [PS-Zn(II)L] catalyst from modified chloromethylated polystyrene. The heterogeneous catalyst has been characterized by IR, PXRD, AAS, TG-DTA, SEM and EDX studies. The catalyst showed its efficient catalytic activity towards the formation of organic cyclic carbonate from epoxides via CO2 fixation at room temperature under 1 atm CO2 pressure in solvent free condition and production of organic carbamates from corresponding amines. The synthesis of carbamates in presence of this catalyst is a phosgene-free protocol where green reagent Dimethyl carbonate (DMC) is used as a carboxylating agent as well as the solvent. The catalyst is highly efficient and reusable even after five cycles.

Two new nickel(II) complexes [Ni(L)Cl 2 ] ( 1 ) and [Ni(L)(NCS) 2 ] ( 2 ) of a neutral tetradentate mono-condensed Schiff base ligand, 3-(2-(2-aminoethylamino)ethylimino)butan-2-one oxime (L) have been synthesized and characterized using different physicochemical techniques e.g. elemental analyses, spectroscopic (IR, Electronic, NMR) methods, conductivity and molecular measurements. The crystal structure of complex ( 2 ) has been determined by using single crystal X-ray diffraction method and it suggests a distorted octahedral geometry around nickel(II) having a NiN 6 coordinating atmosphere. The non-coordinated O H group on the ligand L remain engaged in H-bonding interactions with the S end of the coordinated thiocyanate moiety. These H-bonding interactions lead to O S separations of 3.132 A and play prominent role in crystal packing. It is observed that the mononuclear units are glued together with such O H…S interactions and finally results in an 1D supramolecular sheet-like arrangement. DFT/TDDFT based theoretical calculations were also performed on the ligand and the complexes aiming at the accomplishment of idea regarding their optimized geometry, electronic transitions and the molecular energy levels. Finally the catalytic behavior of the complexes for oxidation of styrene has also been carried out. A variety of reaction conditions like the effect of solvent, effect of temperature and time as well as the effect of ratio of substrate to oxidant were thoroughly studied to judge the catalytic efficiency of the Ni(II) coordination entity.

Chemical fixation of CO2 into fine chemicals is one of the key areas of research today to mitigate greenhouse gas CO2 and its successful utilization as C1 building block. Nanocrystalline MgO has been synthesized by simple precipitation method followed by calcination at 450 °C. The materials are characterized thoroughly by several instrumental tools, which suggested the presence of mesoscopic void space and excellent catalytic activity for the synthesis of organic cyclic carbonates by chemical fixation of CO2 on a wide range of epoxides at atmospheric pressure and room temperature within a short reaction time. Maximum product yields upto 99% for the cyclic carbonates are observed. It also displayed a high catalytic activity in the N-formylation of various amines by using formic acid as reagent (acts both as carbon source and reducing agent) at room temperature with excellent product yields upto 99.5%. This nanocrystalline MgO material showed high recycling efficiency for the cycloaddition of CO2 onto the epoxides and no sign of catalyst deactivation.

A heterogeneous catalyst was prepared by attaching Fe(III) into organically modified chloromethylated polytstyrene and characterized by AAS, IR, PXRD, TG-DTA, UV–Vis, and SEM studies. In presence of H2O2 and KBr as bromine source, the catalyst showed remarkably high conversion with para-selectivity towards the oxidative bromination reaction in acetic acid medium. The catalyst was also very active and highly efficient for the production of spiropiperidine derivatives through multi-component reaction in isopropyl alcohol at room temperature. The catalyst was not leached during the catalytic reactions, moreover, after five cycles the catalytic activity and selectivity of the catalyst were not decreased very significantly.

A new and interesting heterogeneous iron-anchored naphthyl-azo catalyst (PS-Fe-NAPA) has been designed using aminopolystyrene and 2-nitrosonaphthol followed by loading iron in the naphthyl-azo complex. The prepared polymer supported material has been well characterized by FE-SEM, EDAX, TGA analysis, UV–Vis, FTIR, AAS, and elemental analysis. Iron-anchored naphthyl-azo complex exhibited excellent catalytic activity for the selective oxidation of toluene and substituted toluenes containing inactive benzylic C–H bonds in presence of mild oxidant hydrogen peroxide. Additionally, PS-Fe-NAPA complex is highly recyclable up-to six times without loss of its significant catalytic efficiency.

Synthesis of enantiomerically pure drug molecules using functionalized mesoporous materials bearing a chiral moiety is a longstanding goal in heterogeneous catalysis. Herein, we report an efficient and enantioselective one-pot Henry reaction over a highly ordered functionalized mesoporous silica-supported chiral copper-salen catalyst, Cu(II)@AFS-1, in DCM at RT. The catalyst was characterized by UV-Vis, FT-IR spectroscopy, PXRD, N2 adsorption/desorption, HR-TEM, EPR, and thermogravimetric and elemental analyses. The diastereoselective Henry reaction of nitroethane was carried out by using this catalyst to obtain good yields (up to 96%) and ee (up to 95%) of β-nitroalcohols with acceptable dr (3.2 : 1). Additionally, the enantiomerically pure drug (R)-(−)-isoproterenol can be synthesized through the asymmetric Henry reaction of 3,4-dimethoxybenzaldehyde over this chiral mesoporous Cu-catalyst as a key step.

Oleic acid and oleylamine capped 3-D porous CeO2 nanocubes were synthesized by the hot injection method. The surface of the nanocube was modified with 2,4-dimethylphenol (DMP). The reducing and capping abilities of DMP to form Ag nanoparticles were explored to form noble metal nanoparticles over the porous CeO2 nanocubes support at room temperature. The surface modification and formation of Ag nanoparticles over the CeO2 support were thoroughly characterized with FTIR, UV-Vis spectroscopy, XRD, XPS, TEM, HRTEM, STEM, EDX and chemical mapping. This CeO2–Ag nanocomposite was found to have enhanced catalytic activities in the ‘click reaction’ as compared to unsupported Ag nanoparticles and porous CeO2 nanocubes; it was also found to have optimized catalytic activity in the carboxylation of terminal alkynes when Cs2CO3 was used as the base in DMF solvent at 80 °C. The reaction can give the desired product in yields as high as 98% under several experimental conditions via the green pathway. Recycling data showed that the catalyst could be reused five times without considerable loss of its activity and without any deterioration of physical conditions as observed by various characterization methods like TEM, EDX, XRD and XPS.

Synthesis of fine chemicals from the chemical fixation of CO2 is one of the attractive research areas of today to utilise greenhouse gas CO2 in a greener pathway. A flower-like silver nanoparticle grafted mesoporous magnesium oxide (AgNPs@m-MgO) nanocomposite has been prepared by a facile in situ pathway. The materials are characterised by XRD, FTIR, UV-vis, TG-DTA, FESEM, HR-TEM and N2 adsorption–desorption studies. This AgNPs@m-MgO material showed a mesoporous nature with good surface area. It indicated brilliant catalytic activity for both the carboxylation of terminal alkynes by chemical fixation of CO2 (1 atm) and the acylation of various amines by utilizing acetic acid as a reagent in solvent-free conditions showing yields up to 98% and 99% of the propiolic acid and acetamide products, respectively. The reusability of this catalyst has also been verified and it showed high recycling efficiency for both the reactions together with no considerable catalyst deactivation.

Polymer supported transition metal complex catalysts have numerous applications as heterogeneous catalysts due to their ease of synthesis and commercial availability. Ru–Py–Merf was synthesized by anchoring 2-(2-pyridyl)benzimidazole to the polymer matrix, followed by loading of ruthenium salt. This Ru–Py–Merf material was thoroughly characterized by FTIR spectroscopy, UV-vis absorption spectroscopy, FE-SEM analysis, EDAX analysis, CHN analysis, AAS spectroscopy and TGA. Ru–Py–Merf showed excellent catalytic activity in the synthesis of symmetric and asymmetric disubstituted ureas by reductive carbonylation of nitrobenzenes and anilines. The as-synthesized Ru–Py–Merf catalyst is entirely heterogeneous in nature, thermally stable and can be easily reused up to six times.

Structurally characterised two polymeric complexes of Cu(ii) (3) and Mn(iii) (4) of the ligand L (2-(((2-(phenylamino)ethyl)imino)methyl)phenol) have been explored for catecholase-like activity, fluorescence recognition of histidine and catalytic activity towards coupling of aryl iodides with benzamide, leading to N-arylbenzamides. CuO nano-cubes (NCs) prepared by thermal decomposition of the Cu(ii) complex function as photocatalysts for the degradation of methylene blue. Cube-like morphology of CuO nanocrystal and flake-shaped micrometer order Cu(ii) complex have been established from the field emissive scanning electron microscopy (FESEM) images.

Metal oxide nanoparticles (NPs) stabilized by porous carbon materials (PCMs) are very promising for catalysis. In this work, monodispersed small and stable copper oxide (CuO) NPs were prepared with an average size of 10–20 nm without using any capping agent and then these NPs were encapsulated into porous carbon. The chemical and structural properties of the CuO/PCM material were characterized by powder X-ray diffraction, electron microscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and nitrogen sorption. The obtained CuO/PCM nanocatalytic system has been used for the synthesis of N-arylamides from the reaction of aldoximes and aryl halides. Generally, copper(II) salt was used for the preparation of amides from aldoximes using some ligands and bases, but harsh reaction condition, stoichiometric amount of metal, and lack of recyclability limit their applications in industry. An alternative method is the use of heterogeneous catalysts. More importantly, these heterogeneous catalysts could be easily recycled and reused, showing potential application in organic synthesis.

An efficient and recyclable catalytic system composed of palladium nanoparticles embedded over mesoporous TiO2 material (Pd@MTiO2) has been synthesized and its catalytic activity has been explored in Suzuki-Miyaura cross-coupling reaction of aryl halides in water medium. This catalytic system is a very simple and highly active protocol for carrying out the Suzuki coupling of aryl bromide and aryl chloride with boronic acids, which proceed smoothly in excellent yields under mild reaction conditions. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and N2 sorption studies are used to characterize the Pd@MTiO2 material. Environmentally friendly reaction conditions, high product yield, tolerance of variety of functionalities in the reactants and reusability suggested future potential of Pd@MTiO2 for the synthesis of a wide range of biaryl compounds.

Mesoporous zirconium oxophosphate (MZrP-1) composed of porous interconnected network and high specific surface area has been synthesized by using Pluronic P123 as template under evaporation-induced self-assembly (EISA) method. The prepared mesoporous material has been characterized by small-angle powder X-ray diffraction, UHR-TEM (Ultra-high Resolution-Transmission Electron Microscopy) image analysis, and N2 adsorption-desorption, FTIR (Fourier-transform Infrared Spectroscopy) and FE-SEM (Field Emission-Scanning Electron Microscopy) analysis. Mesoporous MZrP-1 catalyst exhibited excellent catalytic activity for the synthesis of cyclic acetals from glycerol and cyclic carbonates from epoxide as starting under solvent-free green conditions. High surface area and abundant acid sites present at the surface of the mesoporous zirconium oxophosphate is responsible for high catalytic activity. The catalyst can be reusable for several reaction cycles without any significant loss in its catalytic activity.

Metallic nanoparticles supported over core-shell metal oxide nanostructures have huge scope in heterogeneous catalysis due to the scope for fine dispersion of the reactive NPs on high surface area material. Silver nanoparticles are supported over Al2O3@Fe2O3 core-shell nanostructured material through aqueous phase reduction method. Ag-Al2O3@Fe2O3 core-shell nanoparticles has been characterized through powder X-ray diffraction, ultra high resolution transmission electron microscopy, scanning electron microscopy, N2 adsorption/desorption isotherm, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy and thermogravimetric analysis. The N2 adsorption/desorption isotherms of Ag-Al2O3@Fe2O3 material are classified as typical type IV isotherm with a large H2 type hysteresis loop for the mesopores. This core-shell mesoporous nanocatalyst showed high catalytic efficiency for the synthesis of 1,4-disubstituted 1,2,3-triazoles in water and acylation of benzyl alcohol under solvent-free conditions. The catalyst is heterogeneous in nature and can be easily recovered and reused without appreciable decrease in its catalytic activity.

Silica coated NiFe2O4 NPs has been synthesized. It has been characterized by XRD, TEM, SEM-EDX and FT-IR. The catalytic activity of the Silica coated NiFe2O4 NPs has been tested for the S-arylation reaction in water with high yield. In this reaction water was used as the green solvent. The effects of solvents, reaction time and catalyst amount for the reaction was reported. This catalyst showed excellent catalytic activity and recyclability. The Silica coated NiFe2O4 NPs catalyst could be easily recovered by filtration and reused more than five times without appreciable loss of its initial activity.

Layered 2D organic–inorganic hybrid perovskite (OIHS) of the diammonium series, 1,5 di-aminepentane tetrachloro mangenate ([NH3–(CH2)5–NH3] MnCl4) was prepared by slow evaporation and reducing temperature method and characterized by single crystal X-ray diffraction analysis. Its structure consists of organic cation, [NH3(CH2)5NH3]+2 extended in a zigzag fashion and inorganic anion, [MnCl6]−2 where Mn2+ is coordinated by six Cl− ion in octahedral fashion. The organic and inorganic segments are alternately stacked along c-axis where inorganic layer is extended through corner-shared octahedra sandwiched by the di-aminopentane molecules. The layers (organic and inorganic) were connected to each other through N–H···Cl hydrogen bonds and van-der Waals interaction to build cation–anion–cation cohesion. The hybrid crystal had orthorhombic non-centrosymetric system having I212121 space group with unit cell parameters a = 7.1742(3) A, b = 7.3817(3) A, c = 23.9650(10) A, V = 1269.13 A3 and Z = 4. The hybrid exhibited excellent catalytic activity towards sulphide and alkene oxidation using aqueous H2O2 as an oxidant. OIHS of the diammonium series [NH3–(CH2)5–NH3] MnCl4; 1,5 di-aminepentane tetrachloro mangenate were prepared by slow evaporation and temperature decrease method, characterized by single crystal X-ray diffraction. This complex exhibits excellent catalytic activity towards sulphide oxidation and alkene oxidation using aqueous H2O2 as an oxidant.

Carboxylic acid functionalized SBA-15 material AFS-1 has been synthesized through post synthetic route and the mesophase of the material has been characterized by powder X-ray diffraction, transmission electron microscopy and N 2 adsorption/desorption studies. Post-synthesis functionalization resulted high loading of carboxylic acid groups at the surface of highly ordered mesoporous silica. The material showed excellent catalytic activity for the production of cyclic carbonates from a wide range of epoxides in the presence of carbon dioxide (CO 2 ) at atmospheric pressure and room temperature. The catalyst can be reused five times without significant loss of its catalytic activity.

CO2 fixation reaction is one of the most challenging chemical transformations not only in the context of environmental remediation but also for effective utilization of abundant carbon sources in nature. Here, we have stabilized palladium nanoparticles (NPs) at the surfaces of a hypercrosslinked porous polymer bearing carbazole and α,α′-dibromo-p-xylene monomeric units to obtain a Pd@HMP-1 nanocatalyst. The material has been thoroughly characterized by powder XRD, high-resolution (HR)-TEM, field-emission (FE)-SEM, Brunauer–Emmett–Teller (BET), thermogravimetric (TGA), and FTIR analysis. Pd@HMP-1 showed excellent catalytic activity towards formylation of amines by carbon dioxide fixation under mild reaction conditions. The high surface area and nitrogen-rich porous surface make the polymer a suitable support for the palladium nanoparticles and endow it with high recycling efficiency in this CO2 fixation reaction.

Nitrogen affluent mesoporous polymeric material was synthesized as a novel support. Ag nanoparticles were finely dispersed at the mesoporous polymer via post-synthetic chemical grafting ove...

CO2 fixation reactions are very demanding both from the perspective of mitigation of greenhouse gases as well as the successful utilization of this abundant C1 source. An efficient and recyclable catalytic system based on palladium nanoparticles embedded on mesoporous TiO2 (Pd@MTiO2) has been developed and it is explored as a heterogeneous catalyst for the synthesis of cyclic carbonates from the respective epoxides and CO2 under atmospheric pressure and at room temperature. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), ultraviolet-visible absorption spectra (UV-vis), X-ray photoelectron spectroscopy (XPS) and N2 sorption studies are used to characterize this Pd@MTiO2 material. Moreover, the catalytic reaction is green as the reaction involves the consumption of greenhouse gas CO2 and the reaction proceeds smoothly without any need for a solvent. High catalytic activity, ease of catalyst recovery from the reaction mixture and excellent recycling efficiency without any significant loss in catalytic performance suggested an environmentally benign catalytic pathway for the synthesis of cyclic carbonates over this Pd-nanocatalyst.

We demonstrate here a green and efficient biogenic synthesis of copper(II) oxide nanoparticles using easily available Ocimum Sanctum leaf extract at room temperature. The biogenic copper oxide nanoparticles have shown excellent activity on N-arylation of cyclic and acyclic amides with aryl and styryl halides. Broad substrate scope, excellent functional group tolerance, and high yields were observed. This protocol is also extended for the N-arylation of substituted aryl amines and nitrogen heterocycles including pyrole, indole, imidazole, benzimidazole, and carbazole. The catalyst was characterized by EPR, UV, FT-IR, BET, AAS, TGA analysis, XPS, XRD, and HR-TEM.

We report the synthesis of a highly active microporous sulphonated monolithic catalyst (HCC-ML-SO3H) through the Friedel–Crafts alkylation reaction between carbazole and α,α′-dibromo-p-xylene in the presence of a Lewis acid catalyst FeCl3 under refluxing conditions, followed by sulphonation reaction (chlorosulfonic acid treatment under controlled reaction conditions). This sulphonated solid acid catalyst can catalyze the ring opening of furanoid moiety of furfuryl alcohol (FA) and subsequent esterification with various alcohols in one-pot to produce levulinate esters, which are potential biofuels. Here the porous organic polymer bearing reactive SO3H groups (HCC-ML-SO3H) acts as a very reactive solid acid catalyst. Due to large surface area and extensive cross-linking this porous polymer is very attractive material for the synthesis of levulinate esters from FA under metal free conditions. The catalyst has been characterized by N2 sorption, HR-TEM, 13C solid state CP MAS NMR, XPS and FT-IR. The catalyst can be reused for four consecutive reaction cycles without appreciable loss of activity.

A new organic–inorganic hybrid iron phosphonate material (FePO-1-2) has been synthesized hydrothermally using etidronic acid (1-hydroxyethylidene-1,1-diphosphonic acid) as an organophosphorus precursor. Under optimized reaction conditions the synthesis has been carried out hydrothermally for 3 days at 180 °C temperature at near neutral pH. The material has been characterized thoroughly by various techniques and its crystal structure has been indexed to a new orthorhombic phase with unit cell parameters of a = 10.995 A, b = 10.395 A, c = 11.793 A, and α = β = γ = 90°. The considerably good Brunauer–Emmett–Teller (BET) surface area of 236 m2 g–1, pore volume of 0.229 cm3 g–1, and robust nature of FePO-1-2 have motivated us to explore its catalytic activity in liquid phase partial oxidation reactions under green conditions. FePO-1-2 exhibits excellent catalytic activity (96% product selectivity, 72% conversion) for selective liquid phase oxidation of cyclohexanone to adipic acid in the presence of molecular ...

Nano-structured magnesium oxide was prepared by calcining its hydromagnesite phase, obtained by simple precipitation using magnesium acetate and ammonium carbonate under ambient condition. This MgO was used as active and reusable catalyst for the Knoevenagel condensation of aromatic aldehydes with malononitrile and ethylcyanoacetate under solvent-free conditions at room temperature. It also exhibits strong activity in solvent-free base catalyzed Claisen-Schmidt condensation of various substituted benzaldehydes with acetophenone. The basic sites of different strengths like surface hydroxyl groups, and low coordination O2− sites may be responsible for the above catalytic activity. The experimental results showed that the nano-MgO has high catalytic activity and can be recycled without significant loss of its activity.

A soft template (Brij-35) controlled nitrogen-doped mesoporous carbon material (N-GMC) was prepared from glucose as a carbon source and melamine as a nitrogen source. The synthesized material was characterized by XRD, SEM, HRTEM, XPS, and Raman spectroscopy and nitrogen adsorption and desorption isotherms. Nitrogen enriches carbon material with high surface area and porous channel showed high CO2 fixation reaction at low temperature and ambient pressure. Excellent catalytic activity and reusability showed towards cyclic carbonate synthesis from various epoxides under metal free condition.

Ruthenium nanoparticles embedded on a mesoporous poly-melamine-formaldehyde material (Ru@mPMF) has been synthesized and characterized by powder XRD, HRTEM, TGA, SEM, EDS, UV–vis diffuse reflection spectroscopy (DRS), Raman spectroscopy, XPS and N 2 adsorption/desorption study. The Ru@mPMF catalyst was excellent for selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) in toluene. Moreover, this catalyst is easily recoverable and it is reusable upto six cycles without notable decrease in its catalytic activity. Profoundly scattered and firmly bound Ru-NPs sites in mPMF might be engaged for the excellent performance of the material. Due to strong binding with the functional groups of the polymer, no indication of ruthenium leaching was there during the reaction. This suggests the actual heterogeneous nature of the material.

An efficient procedure for the one-pot synthesis of propargylamines is A3 coupling in which an alkyne, an aldehyde, and an amine are coupled together. Here, we report that polystyrene supported Cu(I) catalyst is excellent for A3 coupling in water without using any additives or hazardous organic solvents. The polystyrene supported Cu(I) catalyst was synthesized and its catalytic activity was also evaluated in the synthesis of propargylamines in oxidative A3-coupling reaction with benzyl alcohols instead of their aldehydes in water. This protocol offers several advantages such as high yields of the desired product, reaction in aqueous medium and recyclability of the catalyst. It gives well to excellent yields for a variety of substrates. As it acts as heterogeneous catalyst, it can be easily separated from the reaction mixture and reused without appreciable loss of activity. Polymer supported copper catalyst, Cu-PS-ala, acts as a heterogeneous catalyst for the one pot synthesis of propargylamines via A3 coupling reaction in water using aldehydes or alcohols, amines and alkynes.

We have demonstrated the photo-catalytic fixation of CO2 over epoxides for the formation of corresponding cyclic carbonates using a mesoporous Covalent Organic Framework (COF) which acts as a potential photocatalyst with TBAB (Tetrabutyl ammonium bromide), 5 mol% as the co-catalyst under atmospheric pressure in visible light. Greater than 86% yield of the isolated product is achieved with the use of 5 mg of catalyst. The use of Catalyst and co-catalyst TBAB controls the reaction cycle. There is no progress of the reaction occurred in the absence of light (445 nm) even on the elevation of reaction temperature. We have also demonstrated that 25% of the isolated product could be obtained with the use of sunlight using the catalytic cycle. These results open the door to an entirely new class of protocol for photo catalytically fixation of CO2 into cyclic carbonate from epoxide using COF as photocatalyst under visible light.

Levulinic acid (LA), a lignocellulosic biomass-derived compound has been recognized as one of the versatile building blocks for the synthesis of commodity chemicals having biofuel properties together with potential as precursor for the synthesis of several value-added pharmaceuticals and polymers. Herein, we report the synthesis of catalytically active functionalized porous organic polymer and its utilization as heterogeneous organocatalyst for the synthesis of EL from LA in very high yield. Here, sulfonic acid functionalized porous organic polymer SBZ@POP have been prepared via simple Friedel-Crafts alkylation of benzene with dimethoxymethane followed by sulfonation of the aromatic rings. The structure and properties of the material was examined through PXRD, N2 sorption, HR TEM, 13C CP-MAS NMR, NH3-TPD, TG-DTA and FTIR analysis. Our characterization data suggested nanoscale porosity with high surface acidity in SBZ@POP. The effects of reaction time, catalyst loading, molar ratio of levulinic acid to ethanol and reaction temperature were studied thoroughly to optimize the catalytic activity of SBZ@POP. Under optimized reaction conditions EL yield of 88 % has been achieved with 1:15 molar ratio of LA to ethanol under refluxing conditions in 10 h. This porous organic polymer based organocatalyst displayed good recyclability for consecutive five reaction cycles suggesting the sustainable application potential of this acidic organocatalyst.

We have designed mesoporous AgNPs decorated COF (Ag/TFPG-DMB COF) nanomaterial which has been formed by an easy ex-situ synthetic method. The synthesized material is characterized by FTIR, PXRD, UV–vis, N2 adsorption–desorption studies, TEM, FESEM and XPS. The material showed the generation of identical mesopore at 3.9 nm. It is observed that the material can perform as both thermally and photochemically active catalyst for carbamate synthesis and one-pot reduction and N-formylation of nitroarenes respectively. The catalytic activity of the Ag/ TFPG-DMB COF nanomaterial is checked for green synthesis of carbamates from different amines and alcohols under 1 atmospheric pressure of CO2 with excellent yield (upto 95 %) as well as with high TOF value (182 h−1) and high selectivity. Additionally, the Ag/ TFPG-DMB COF nanomaterial is also applied as a potentially active photocatalyst for one-pot nitroarene reduction along with N-formylation reaction under sunlight irradiation in green reaction conditions with exceptionally high yield of formylated products upto 99 % as well as with high TOF value (762 h −1). The catalyst efficiently reduced and formylated para-nitrophenol, a potential water pollutant, which elaborates its scope as an efficient catalyst for water purification also. The catalyst recyclability is also checked for five reaction cycles for both the reactions and the Ag/TFPG-DMB COF material showed outstanding recycling ability without any noticeable leaching of active metal or catalyst degradation.

Hollow spherical ZnO particles with porous exterior surface are successfully synthesized and employed as a cost effective heterogeneous catalyst for CO2 fixation in a wide range of epoxides at atmospheric pressure and room temperature to form cyclic carbonates. In fact, conversion of carbon-di-oxide into value aided chemicals is one of the major areas of contemporary research. This versatile material is also capable to catalyze acylation of amines in solvent free condition. The end products of both the reactions i.e. cyclic carbonate and N-acylated amines have huge industrial importance. The pristine ZnO nanomaterial without incorporation of metal nanoparticles, has shown excellent reusability up to five consecutive reaction cycles without considerable loss in its efficiency which is quite encouraging for industrial realization.

Recently CO2 fixation has gained large extent attention due to its potential applications as an abundant C1 resource and variety of value-based fine chemicals that can be synthesized through this fixation. In this paper copper nanoparticles incorporated covalent organic framework based (Cu-NPs@COF) material was synthesized by a simple in-situ process. The material was characterized by various instrumental techniques such as FTIR spectra, PXRD, UV–vis spectra, HR-TEM, XPS, N2 adsorption desorption, TG-DTA, AAS analysis, etc. The material is potentially very active catalyst in fixation of carbon dioxide to synthesize 2-oxazolidinones as well as benzimidazoles. 2-oxazolidinones was prepared from propergylamine in presence of 1,8-Diazabicyclo(5.4.0)undec-7-ene (DBU) base at 50 °C under 1 bar CO2 pressure in acetonitrile solvent medium and the desired product was obtained up to 96 % yield after 12 h of reaction. Again the catalyst can fix CO2 (1 bar pressure) in o-phenylenediamine/its derivatives to produce benzimidazoles with moderate to an excellent yield of the desired product in presence of environmentally benign hydrogen source dimethylamine borane (DMAB) under green solvent mixture (ethanol/water). Furthermore, the catalyst is very easily recyclable and reusable without considerable loss of active site copper metal for many catalytic cycles (up to six cycles was tested).