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In this report, we documented novel strategy for the synthesis of bioactive polysubstituted 2-amino-4H-chromine derivatives under a heterogeneous Al-MCM-41-LDH@APTES (ALAM) catalysis. A synthetic procedure is developed to prepare Al-MCM-41-LDH@APTES (ALAM) heterogeneous basic catalysts. Mesoporous Al-MCM-41 is functionalized by known grafting chemistry via layered double hydroxide (LDH) nanosheets and (3-aminopropyl)triethoxysilane (APTES) moiety as a basic organocatalyst. The resulting catalysts contain amino group functionality on the external surface as well as inside the layers and the basicity can be tuned by the loading of APTES. The samples were fully characterized by 29Si and 13C CP/MAS NMR, infrared absorption spectroscopy, TEM, XPS, EDX, TGA, XRD, CO2-TPD, N2 adsorption isotherms measurements, and they were successfully examined for the cascade type Knoevenagel–Michael addition reactions. The product yields associated with these substrates were optimized, and key reaction parameters affecting the yields were identified. The present catalytic method is simple and robust for diversity oriented synthesis which proceeds good to excellent yields without generating any hazards waste. The broad substrate scope, excellent functional group compatibility makes this protocol highly useful towards synthesis of polysubstituted α-cyanoacrylates, α-cyanoacrylonitriles and 2-amino-4H-chromenes with an electron-donating or electron-withdrawing group. We have also successfully established a flow reaction system, gram-scale synthesis as well as catalyst recyclability up to six catalytic cycles without appreciable loss of its activity.

The abolition of environmental pollutants and production of hydrogen (H2) from water using a heterogeneous photocatalyst is a demanding science of the current scenario to solve the increasing environmental pollution and worldwide energy catastrophe in modern life. To validate this purpose, the design of low-cost and durable semiconductor-based photocatalysts with great light absorption capacity becomes the most challenging issue for researchers. Regarding this, herein the phosphotungstic acid (HPW)-anchored Zr6O4(OH)4(BDC)6 (UiO-66) metal-organic framework (MOF), i.e., HPW@UiO-66, has been prepared by a hydrothermal method and is efficient, stable, and capable of harvesting solar energy toward the degradation of tetracycline hydrochloride (TCH) and H2 production in the presence of a sacrificial donor. The ionic interaction between HPW and UiO-66 plays a key role toward the photostability and charge-transfer mechanism of the composite and is well characterized with X-ray diffraction, UV diffuse-reflectance spectroscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy. A total of 30 wt % HPW@UiO-66 shows a maximum degradation of about 87.24% of a 20 ppm TCH solution in 60 min of solar-light irradiation and about 353.89 μmol/h of H2 production. The conduction- and valence-band potentials are well characterized with Mott-Schottky measurement and a delay charge recombination process through electrochemical impedance spectroscopy. The proposed mediator-free Z-scheme-oriented electron-hole migration route is well supported by photoluminescence, and the scavenger test well explains the better charge-carrier separation and high catalytic performance of the prepared composite. This research will bestow an advantageous blueprint to fabricate novel and challenging photocatalysts toward the photocatalytic treatment of environmental pollutants and H2 evolution.

Achieving photocatalytic organic transformation reactions by using a visible light induced semiconductor-based photocatalyst is promising as a green and sustainable approach. In the present study, Au/Pd bimetallic alloy loaded amine (APTES) functionalised LDH (Layered double hydroxide)–MCM-41 composite was prepared through an in situ co-precipitation followed by a co-reduction method. The structural phases, textural properties, optical behaviour, morphological aspects, chemical states and functional groups of the photocatalysts were thoroughly analysed by powder X-ray diffraction (PXRD), high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible diffuse reflectance (UV-vis DRS), fourier-transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies. Moreover, the formation of an alloying structure between Au and Pd was confirmed from PXRD, HRTEM and UV-vis absorption spectra. We investigated one-pot synthesis of imines through photoalkylation of benzyl alcohol with nitrobenzene over Au/Pd bimetal alloy loaded on amine functionalised LDH–MCM-41 composite and it demonstrated imine yield of around 3.1 times (68%) more than the parent LDH (22%). The alloy nanoparticless efficiently harvest light and possess higher photocatalytic activity with respect to single Pd and Au nanoparticles. Due to the alloying structure develops charge heterogeneity on the surface of alloyed nanoparticles and enhances the interaction between metal surface with substrate molecule which promotes the coupling between photo generated benzaldehyde with aniline to form imine. Characterisation such as photoluminescence (PL), time-resolved photoluminescence (TRPL), electrical impedance spectroscopy (EIS) and photocurrent density measurements further proved the superior photoactivity towards imine synthesis. These photocatalytic tandem reactions, therefore, have great potential as an effective pathway for the one-pot organic synthesis and transformation of organics in an environmentally friendly way.

Visible light harvesting by heterogeneous photocatalysts and their applications in organic transformation reactions for the synthesis of target molecules are quite demanding science in the current scenario. In this regard, herein, a novel metal (Au/Pd)-functionalized metal organic framework (UiO-66-NH2) was synthesized to carry out the Suzuki–Miyaura coupling (SMC) reaction under visible light irradiation at ambient conditions. In order to justify the claim regarding the formation of alloys, crystallinity, morphology, particle size, proper separation of excitons, elemental content and their environment, various sensitive characterization techniques such as XRD, XPS, HRTEM, BET surface area and UV-vis analysis were employed. A mechanistic approach by means of experimental investigations revealed that the strong LSPR effect of Au facilitated the transfer of electrons to the Pd surface to make the surface negatively charged and suitable for the activation of aryl halides. The formed electropositive Au nanoparticles were converted to Au0 by accepting the photo-induced electrons from pristine UiO-66-NH2 and made available only holes at VB for the activation of phenylboronic acid. Among all the synthesized photocatalysts (1 : 2), Au/Pd@UiO-66-NH2 showed the highest activity (>99%) with TOF = 426 h−1 in an EtOH/H2O medium towards the SMC reaction, and the highest activity of this catalyst was supported by the electron gas model, LSPR effect (UV-vis) and active species separation (PL) analysis. The bimetallic noble nanoparticle-anchored UiO-66-NH2 not only expands the synthesis scope of C–C coupling by the SMC reaction under ambient conditions but will also inspire the further exploration of the activation of various reactants towards a wide range of organic transformation reactions.

A series of sulphate modified Al-MCM-41 acid catalysts are synthesized following impregnation and co-condensation methods The physico-chemical characterizations of all the samples are done by XRD, FT-IR, TGA/DTA, TPD, N 2 adsorption and desorption study, SEM, HRTEM and EDAX etc. The structural advantages of Al-MCM-41 such as large specific surface area, wide pore size and pore volume and Bronsted and Lewis acid sites favor the coupling reaction. The catalysts endorsed the direct addition of alcohols to alkynes as well as their coupling with styrenes. The various combinations of alcohols with alkynes and styrenes are compatible with diverse functional groups to synthesize a substituted aryl ketones, as well as olefins with good to excellent yields. Additionally, the approach is advantageous in terms using alcohols, discounting the pre-functionalization and generation of waste by-products. Used precursors, alkynes and styrenes, are valuable since they are stable and found in many biologically active compounds. This current research work provides supplements to C C bond formation methodologies as a single step with atom economy and recyclable approach under mild and environmentally benign conditions.

Photocatalytic organic transformations driven by functionalised metal organic frameworks (MOFs) are a green perspective for fine chemical synthesis. In the class of highly porous materials, MOFs are unparalleled in their degree of tunability and structural diversity and range of physical and chemical properties such as large surface area, permanent porosity, large void volumes, and framework flexibility, because of which they can act as a sustainable alternative for inorganic semiconductors. MOFs are the latest class of ordered porous solids being intensively studied as a novel class of hybrid organic–inorganic materials as nanophotocatalysts in the field of chemistry, materials science, chemical engineering, etc. Although the photocatalytic application of MOFs is still in the early stages compared with their other applications such as gas storage, separation, and heterogeneous catalysis, the currently available results have revealed that functionalised MOFs are very active as photocatalysts. The present review aims to discuss the various synthetic methods, post-synthetic modifications, MOF catalysed organic reactions and proposed mechanistic pathways for photoinduced organic transformations.

This work reports an amine modified meso Al2O3@MCM-41, particularly the ordered mesoporous silica, as a catalyst for the formylation of amines with carbon dioxide (CO2) and with dimethylamine-borane (DMAB) as a green reducing source. This newly developed catalytic system represents a heterogeneous and environmentally benign protocol. Besides this, the catalyst could be reused for five consecutive cycles without any significant loss in its catalytic activity towards the synthesis of formamides. The amine modified meso Al2O3@MCM-41 catalysts were well characterized by high and low angle XRD, temperature programmed desorption (TPD), BET-surface area, TGA/DTA and FT-IR analysis techniques. The effect of various reaction parameters such as temperature, CO2 pressure, time and the ratio of substrates to DMAB for the synthesis of formamides has been investigated. The developed protocol can be applicable for the synthesis of most important key intermediates like formoterol, orlistat, leucovarin and iguratimod in biologically active compounds.

In recent years, metal/metal oxide functionalized mesoporous materials have received increasing attention in science and technology due to their fascinating properties, such as a large surface area, mesoscopic bulky shape, and interconnected porous structures enabling them to be one of the most promising materials for catalysis and photo catalysis. This review summarizes the recent developments in design, preparation and applications of transition metal/metal oxide promoted MCM-41 for production of hydrogen energy and removal of aqueous pollutants. After a brief introduction of these materials and synthetic strategies, their characterizations and applications in aqueous pollutant degradation by photocatalysis/photo-Fenton processes and H2 energy production by photocatalytic water splitting are summarized. Finally, the future perspectives directions for this promising field are also discussed.

Nowadays, inorganic–organic hybrid materials having pores in the mesoporous range are an intensively studied new category of demanding materials. By template synthesis, the coupling of inorganic and organic components gives pore sizes between 2 and 15 nm with very high surface area. The inorganic–organic hybrid materials were prepared in two ways: one was by co-condensation and the other by post-synthesis method. The inorganic part provides mechanical strength and the organic part shows functional activities. This review gives an overview of the preparation, properties, and potential applications of these materials in the areas of adsorption of pollutant gases like CO2 and heavy metals and in catalysis. Their activity is found to be very impressive in all these fields and it is hoped to be improved in the near future.

The current research paper deals with the study of palladium doped TiO2 based photocatalytic system to remove cyanide from coke oven wastewater. The photocatalytic activity was improved by employing hydroxyapatite nanoparticles, which serves to enhance the concentration of cyanide near the photoactive sites of TiO2 and also prevents its agglomeration. Further, to enhance the rate of photocatalytic degradation of cyanide under visible light irradiation an iron tetracarboxy phenyl porphyrin sensitizer (Fe-TCPP) was employed. The structural and morphological characterization of the synthesized catalysts were carried out by Fourier transformation infrared spectroscopy (FTIR), X-ray diffraction (XRD), photoluminescence (PL) emission spectra, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and ultraviolet diffuse reflectance spectroscopy (UV- DRS). The photocatalytic activity of the TiO2-Pd-HAP-Fe-TCPP- nanocomposite has been evaluated on degradation of cyanide under visible light irradiation using a photocatalytic reactor system. The results demonstrate the existence of synergistic effect between TiO2-Pd-HAP and Fe-TCPP sensitizer on removal of cyanide. Almost 90% of cyanide degradation was achieved at pH 11 within a short time span of 90 min, using the TiO2-Pd-HAP -Fe-TCPP nanocomposite. The photocatalytic degradation of cyanide by the nanocomposite follows pseudo-first order kinetics. The apparent rate constant (kapp) value of the TiO2-Pd-HAP-Fe-TCPP nanocomposite is estimated to be 11.6 and 4.3 time higher than that of bare TiO2 and TiO2-Pd-HAP respectively. Further, at this condition, >90% toxicity removal was achieved in the photocatalytic system even at a very high initial concentration of cyanide. Therefore, the Fe-TCPP-TiO2-Pd-HAP nanocomposite system can be considered as an alternative technique for removal of cyanide from coke oven wastewater.

The MCM-41 supported Cs2.5H0.5PW12O40 and K2.5H0.5PW12O40 salts were synthesized by incipient wetness impregnation method. The solids were characterized by N2 adsorption–desorption isotherms, FT-IR, XRD, and temperature programmed desorption, etc. This catalyst has been found to exhibit excellent activity for acetylation of phenolic compounds. The catalyst is stable and reusable giving 96% conversion with 100% selectivity towards acetate products.

A series of Cu salts of heteropoly acid (CuxH3−2xPW12O40) supported MCM-41 catalysts (CuxH3−2xPW12O40/MCM-41) was synthesized by wet impregnation method and thoroughly characterized by using various analytical techniques, viz., X-ray diffraction, UV−vis diffused reflectance spectroscopy (UV−vis DRS), nitrogen adsorption desorption, temperature-programmed reduction (TPR), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). From XRD and FT-IR studies, we confirmed that the Keggin structure of heteropoly acid (HPA) is retained in Cu salt of HPA. Heck vinylation was performed to examine the catalytic properties of the catalysts. The 50 wt % CuxH3−2xPW12O40/MCM-41 showed remarkable catalytic performance of phenyl iodide (98% conversion) to cinnamic acid in aqueous medium compared with MCM-41 and other catalytic systems.

The paper reports the synthesis, surface and textural characterization of copper and amine modified MCM-41 and its application for the single step amination of benzene to aniline at 70 °C. Varying the amount of Cu different Cu/amine modified MCM-41 samples was synthesized by co-condensation and impregnation method. The samples were characterized by nitrogen adsorption–desorption, X-ray powder diffraction, Fourier-transform infrared spectroscopy (FT-IR), 29Si magic-angle spinning (MAS) and 13C Nuclear Magnetic Resonance (NMR) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). X-ray diffraction patterns indicate that the modified materials retain the standard MCM-41 structure. FT-IR and DRS results indicated that Cu and amino groups are incorporated into the Si–O framework and frame wall respectively. NMR showed higher degree of condensation of materials in framework position. Cu-amine-MCM-41 samples showed significant catalytic activity for single step amination of benzene in acetic acid–water medium under mild reaction conditions using hydroxylamine as aminating agent. The Cu-amine-MCM-41 (Si/Cu = 20) showed highest benzene conversion (72.2%) and 100% selectivity for aniline.

This paper reports preparation, characterization of amine modified mesoporous crystalline MCM-41 and its application in Knoevenagel condensation reaction. Amine modified MCM-41 was prepared by co-condensation and post-synthesis methods. The samples were characterized by X-ray powder diffraction, Fourier-transfer infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron micrograph (SEM), 29Si magic-angle spinning (MAS), nuclear magnetic resonance (NMR), diffuse reflectance spectra (DRS), nitrogen adsorption–desorption and CHN analysis. X-ray diffraction patterns indicate that the modified materials retain the standard MCM-41 structure. SEM study exhibits that the arrangement of particles for 12.8% amine modified MCM-41 is well ordered and spherical in nature. CHN analysis supports that complete hydrolysis of ethoxy groups take place in 12.8% amine modified sample. From the NMR study it is confirmed that the surface coverage is 40% in 12.8% amine modified sample. The base catalytic activity of hybrid MCM-41 materials such as amine (post-synthesis and co-condensation methods) and surfactant functionalized materials for condensation reaction between benzaldehyde and diethyl malonate in solvent free, room temperature synthesis of cinnamic acid was evaluated and correlated with the surface and textural properties. Sample containing 12.8 wt% amine loaded by co-condensation method showed highest malonic ester conversion (92%) and selectivity (98%) for cinnamic acid.

A series of copper catalysts supported on mesoporous molecular sieves MCM-41 with copper loading varying from 2 wt% to 10 wt% were synthesized by impregnation method using aqueous copper nitrate solution as the precursor. The samples were characterized by nitrogen adsorption–desorption, X-ray powder diffraction, FT-IR, UV-diffuse reflectance spectra and temperature programmed reduction. X-ray diffraction patterns indicate the presence of crystalline CuO phase above 4 wt% copper loading. TPR patterns at low temperatures reveal the presence of highly dispersed copper oxide on the surface of the support and the profiles at high temperatures indicates bulk copper oxide. The catalytic activity of the samples was evaluated towards benzene oxidation using H 2 O 2 as the oxidant in acetic acid solvent at room temperature. The effect of reaction parameters, i.e. time, temperature, catalyst amount, amount of H 2 O 2 , solvent and alkyl substitution on the substrate, were also investigated. Among the catalysts studied, 4 wt% copper loaded MCM-41 showed maximum conversion (21%) and selectivity (94%) towards phenol.

Nowadays, inorganic–organic hybrid materials having pores in the mesoporous range are an intensively studied new category of demanding materials. By template synthesis, the coupling of inorganic and organic components gives pore sizes between 2 and 15 nm with very high surface area. The inorganic–organic hybrid materials were prepared in two ways: one was by co-condensation and the other by post-synthesis method. The inorganic part provides mechanical strength and the organic part shows functional activities. This review gives an overview of the preparation, properties, and potential applications of these materials in the areas of adsorption of pollutant gases like CO2 and heavy metals and in catalysis. Their activity is found to be very impressive in all these fields and it is hoped to be improved in the near future.

The mesoporous molecular sieve MCM-41 was synthesized by sol–gel method using tetraethyl orthosilicate (TEOS), cetyl trimethyl ammonium bromide (CTAB), aqueous NH3 and water. A series of sulfate modified MCM-41 was prepared by incipient wetness impregnation method using H2SO4 as sulfatising agent. The samples were characterized by BET surface area, X-ray diffraction, FT-IR and TG–DTA. The catalytic activity of the samples was evaluated for nitration of phenol with nitric acid in dichloro ethane (DCE) medium, at room temperature. The effect of reaction parameters, i.e. time, concentration of nitric acid and phenol/nitric acid ratio were also investigated. Modification with sulfate opened new opportunities to generate active Bronsted and Lewis acid sites in the stabilized nanostructure MCM-41. Among the catalysts screened, 4 wt.% sulfated MCM-41 showed maximum activity (93%), with 90% selectivity towards ortho-nitrophenol.

The catalysts exhibit excellent activity for the acetylation of phenols and benzyl alcohols.

A series of Cs salt of phosphotungstic acid (Cs-PTA) supported on MCM-41 (Cs-PTA/MCM-41) was synthesized by a wet impregnation method and thoroughly characterized by using various analytical techniques, viz. X-ray diffraction, UV-Vis diffused reflectance spectroscopy (UV-Vis DRS), nitrogen adsorption desorption, scanning electron microscopy (SEM), Infrared spectra (FTIR), temperature programmed reduction (TPR), and temperature programmed desorption (TPD). The spectroscopic results revealed that Cs-PTA is highly dispersed on a MCM-41 surface. The 50 wt.% Cs-PTA supported on MCM-41 showed remarkable catalytic performance toward acylation of anisole reaction. The catalyst is regenerable by simple calcinations without appreciable loss in catalytic activity.

The Mobil Composition of Matter No. 41 (MCM-41) containing Cu and Al with Si/Al ratios varying from 100 to 10 and 1 to 6wt.% of Cu was synthesized under hydrothermal and impregnation conditions, respectively. The samples were characterized by nitrogen adsorption-desorption measurements, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), and (29)Si and (27)Al magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectra. X-ray diffraction patterns indicate that the modified materials retain the standard MCM-41 structure. TPR patterns show the two-step reduction of Cu species. TPD study shows that Cu-impregnated Al-MCM-41 samples are more acidic than Al-MCM-41. From the MAS-NMR it was confirmed that most of the Al atoms are present tetrahedrally within the framework and some are present octahedrally in extraframework position. Impregnation of Cu shifted Al to the extraframework position. The catalytic activity of the samples toward hydroxylation of phenol in aqueous medium was evaluated using H(2)O(2) as the oxidant at 80 degrees C. The effects of reaction parameters such as temperature, catalyst amount, amount of H(2)O(2), and solvent were also investigated. Sample containing 4wt.% copper-loaded Al-MCM-41-100 showed high phenol conversion (78%) with 68% catechol and 32% hydroquinone selectivity.