Multicomponent Synthesis of 2, 4, 6-Triarylpyridine Analogues As Antibacterial And Antiurease Agents

Five new 2,4,6-triarylpyridine analogues with potential biological importance have been synthesized using the multicomponent reaction (MCR) solid support catalyst synthetic approach. This green synthesis furnished method simplicity, reduce reaction time, and excellent yield, along with an additional feature of catalyst reusability. A number of spectroscopic techniques such as 1H-NMR, IR, and mass spectrometry, confirmed structures of the newly synthesized compounds. Antibacterial and anti-urease activities of these compounds were evaluated. Results revealed that compounds 4a, 4c, 4d, and 4e exhibit significant inhibition against gram-positive bacterial pathogens. Furthermore, all synthesized compounds showed potent urease inhibitory activity with IC50 values ranging from 12.8 ± 1.04 to 23.7 ± 0.23 µM when compared with the standard inhibitor thiourea (IC50 21.0 ± 0.23 µM).In addition, the synthesized derivatives were subjected to density functional theory (DFT) calculations (DFT) to determine the energy of the molecules having biological potential.

Phthalocyanine-nanoparticle conjugates supported on inorganic nanofibers as photocatalysts for the treatment of biological and organic pollutants as well as for hydrogen generation

This thesis reports on the synthesis, photophysicochemical and photocatalytic properties of various zinc phthalocyanines (Pcs). For enhanced properties and catalyst support, the reported Pcs were conjugated to different nanoparticles (NPs) through chemisorption as well as amide bond formation to yield Pc-NP conjugates. For increased catalyst surface area and catalyst reusability, the Pcs and some of their conjugates were also supported on electrospun inorganic nanofibers i.e. SiO2, hematite (abbreviated Hem and has formula α-Fe2O3), ZnO and TiO2 nanofibers. The effect that the number of charges on a Pc has on its antimicrobial activities was evaluated by comparing the photoactivities of neutral, octacationic and hexadecacationic Pcs against S. aureus, E. coli and C. albicans. The extent of enhancement of their antimicrobial activities upon conjugation (through chemisorption) to Ag NPs was also studied in solution and when supported on SiO2 nanofibers. The results showed that the hexadecacationic complex 3 possessed the best antimicrobial activity against all three microorganisms, in solution and when supported on the SiO2 nanofibers. Covalent conjugation of Pcs with carboxylic acid moieties (complexes 4-6) to amine functionalised NPs (Cys-Ag, NH2-Fe3O4 and Cys-Fe3O4@Ag) resulted in enhanced singlet oxygen generation and thus antibacterial efficiencies. Comparison of the photodegradation efficiencies of semiconductor nanofibers (hematite, ZnO and TiO2) when bare and when modified with a Pc (complex 6) were evaluated. Modification of the nanofibers with the Pc resulted in enhanced photoactivities for the nanofibers with the hematite nanofibers being the best. Modification of the hematite nanofibers with two different Pcs i.e. monosubstituted (complex 5) and an asymmetrical tetrasubstituted Pc (complex 6) showed that complex 6 better enhanced the activity of the nanofibers. Evaluation of the hydrogen generation efficiencies of the bare and modified TiO2 nanofibers calcined at different temperatures demonstrated that the anatase nanofibers calcined at 500 oC possessed the best catalytic efficiency. The efficiency of the TiO2 nanofibers was enhanced in the presence of the Co and Pd NPs as well as a Pc (complex 7), with the extent of enhancement being the greatest for the nanofibers modified with the Pd NPs. The reported findings therefore demonstrate the versatility of applications of Pcs for different water purification techniques when supported on different nanomaterials.

Urea-Assisted Synthesis of Mesoporous TiO2 Photocatalysts for the Efficient Removal of Clofibric Acid from Water

Mesoporous TiO2 photocatalysts intended for the advanced removal of clofibric acid (CA) from water were synthesized by the sol-gel method in a medium containing cetyl-trimethyl-ammonium bromide (CTAB) and urea, using either ethanol or isopropanol to dilute the TiO2 precursor. The activation of the samples was undertaken at 550, 650 and 750 °C. The XRD revealed that the nature of the solvent resulted in significant differences in the anatase-to-rutile ratios obtained at different temperatures. The specific surface area values were situated between 9 and 43 m2g−1 and the band gap values were similar for all the samples. The photocatalytic activity of the prepared samples was examined for the degradation of CA, an emergent water contaminant. The photocatalytic tests performed under UV-A irradiation revealed that the photo-reactivity of these materials depends on the calcination temperature. The best results were obtained for the samples calcined at 750 °C, which showed high yields of CA elimination, as well as almost complete mineralization (over 95%) after 180 min of reaction. Good results in terms of catalyst reusability in the reaction were found for the catalyst showing the highest photo-reactivity. Therefore, the samples can be considered good candidates for future water remediation applications.

Application of Agricultural Waste as Heterogeneous Catalysts for Biodiesel Production

In this modern era, it has become essential to transform waste materials into valuables because of their excessive availability, along with achieving the targets of environmental protocols and waste management policies. With a growing population, the utilization and consumption of agricultural products have been increased extensively. In addition, it has increased the probability of agricultural waste generation. Waste produced from agricultural sources is considered as a viable source for synthesizing economical and ecofriendly catalysts and suitable ways for its disposal are sought. This study is targeted at agricultural waste-derived heterogeneous catalysts, which have been effectively employed for biodiesel generation. The types of agricultural waste, catalyst synthesis techniques, recent literature stated for agricultural waste-derived catalysts to produce biodiesel, the elemental composition and catalytic activity of agricultural waste ashes, the effect of reaction parameters to maximize biodiesel yield and catalyst reusability have been discussed. This work concludes that catalysts derived from agricultural waste are efficient in transesterification reaction, and they are easy to produce, and are cheap and ecofriendly. Moreover, this study encourages researchers to see the options for unexplored agricultural waste, which can be potentially converted into useful materials

Synthesis of Palladium and Copper Nanoparticles Supported on TiO2 for Oxidation Solvent-Free Aerobic Oxidation of Benzyl Alcohol

The use of metal oxides as supports for palladium and copper (Pd–Cu) nanoalloys constitutes a new horizon for improving new active catalysts in very important reactions. From the literatures, Pd-based bimetallic nanostructures have great properties and active catalytic performance. In this work, nanostructures of titanium dioxide (TiO2) were used as supports for Pd–Cu nanoparticles catalysts. Palladium and copper were deposited on these supports using the sol-immobilisation method. The composite nanoalloys were characterized using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The catalyst was evaluated for the oxidation of benzyl alcohol. The effect of the Cu–Pd ratio using sol-immobilization methods supported on TiO2 was investigated. The results show that monometallic Cu/TiO2 was observed to have a low activity. However, as soon as the catalyst contained any palladium, the activity increased with a significant increase in the selectivity towards isomerization products. The influence of support and temperature were investigated. Furthermore, the catalyst reusability was also tested for oxidation of benzyl alcohol reactions, by repeatedly performing the same reaction using the recovered catalyst. The Pd–Cu/TiO2 catalyst displayed better reusability even after several reactions

Environment-Friendly Deoxygenation of Non-Edible Ceiba oil to Liquid Hydrocarbon Biofuel: Process Parameters and Optimization Study

Non-edible Ceiba oil has feasibility as a sustainable biofuel resource in tropical countries that act as alternative to a portion of the fossil fuels used today.Catalytic deoxygenation of the Ceiba oil (high O/C ratio) was conducted to produce hydrocarbon biofuel (high H/C ratio)over NiO-CaO5/SiO2-Al2O3catalyst with aims of high diesel selectivity and catalyst reusability. In the present study, Box-Behnken experimental design was used to evaluate and optimize liquid hydrocarbon yieldby considering following reaction factors: catalyst loading (1-9 wt.%), reaction temperature (300 - 380°C) and reaction time (30 -180 min). It was discovered that the optimum yield for hydrocarbon fractionsn-(C8 – C20) was 77% under deoxygenation condition of 5 wt.% catalyst loading, reaction temperature of 340°C within 105 min. Besides, deoxygenationmodel indicated that interaction effects of catalyst loading-reaction time influence the deoxygenation activity greatly. Based on the product analysis, oxygenated species(e.g. CO2 and CO) were removed mainly via decarboxylation/decarbonylation (deCOx) pathways. The NiO-CaO5/SiO2-Al2O3 catalyst is stable for five consecutive runs with hydrocarbon fractions within range of 66-75% and n-(C15+C17) selectivity of 64-72% as well. The stability profile of NiO-CaO5/SiO2-Al2O3 catalyst indicated that the catalyst able to maintain deoxygenation reactivity throughout five cycles with hydrocarbon yield of 66-75% and n-(C15+C17) selectivity of 64–72 %. However, coke deposition was noticed for the spent catalyst after several times of usage, which due to the high reaction temperature above 300 oC.

Improved xylanase Characteristics upon enzyme entrapment Isolated from Thermomyces lanuginosus C9

Xylanases from microbial sources assume basic jobs in an assortment of industrial applications as a biocatalyst, and its applications generally require immobilization on supports to upgrade their stability. Enzyme immobilization is a thrilling decision to show signs of improved strength of enzymatic procedures. In this work, two sorts of polymeric backings (agar-agar and calcium alginate) are utilized to immobilize β-1,4-xylanase from Thermomyces lanuginosus C9 by entrapment, and afterward, biochemical properties of the entangled enzymes were performed. To create immobilized catalyst beads centralization of 4% agar while mix of sodium alginate 5% and calcium chloride 0.4 M was seen as ideal. Ideal reaction time for agar and calcium alginate immobilized protein increments from 10 to 25 and 30 min, separately. The incubation temperature expanded from 70°C to 75°C for agar however stayed unaltered for calcium alginate. The pH profile of free and immobilized xylanase was generally equal in both cases. Be that as it may, both the strategies changed the active boundaries of immobilized β-1,4-xylanase rather than free protein. High sub-atomic load of xylan limits dispersion which brings down the Vmax estimation of immobilized protein while Km value expanded. In contrast with agar-agar, protein immobilized inside calcium alginate display wide thermal stability and kept up 86.6% of its underlying activity at 80°C up to 150 min. Be that as it may, biotechnological portrayal demonstrated that the catalyst reusability was the most surprising discovery, predominantly of agar-agar immobilized xylanase, which held 31% activity after 7 cycles. These outcomes prove the biotechnical and monetary advantages of immobilization which help in an assortment of industrial applications.

An Efficient Synthesis Of α, β Unsaturated Ketones Via Claisen–Schmidt Condensation Reaction Using Amino Acid Based Ionic Liquids

: Synthesis of chalcone by Claisen–Schmidt condensation using recyclable L- aspartic acid coupled imidazolium-based ionic liquid as a green synthetic approach has been developed. Present work offers significant advantages such as high yield, enhanced reaction speed even at room temperature, catalyst reusability, and the involvement of non-toxic reagents. Background: Chalcones are a flavonoid family and have pharmacological and biological activities. It includes antibacterial, antifungal, immunosuppressive, and anti-nociceptive properties. Objective: Ionic liquid has emerged as a powerful tool for molecular organic solvents and wide liquid range, ease of recovery and reuse, and making them a greener alternative to volatile organic solvents. Thus, our objective was to employ them as dual catalyst and solvent systems to synthesize chalcone via CS condensation in the present work. Method: In a typical experiment, benzaldehyde (10 mmol), acetophenone (10 mmol), and 2.5 mol% (L-AAIL) ionic liquid were mixed in a 50 mL round-bottom flask. The reaction was preceded quickly at room temperature with stirring, the resulting mixture became a biphasic system with the residue at the bottom and the upper phase containing some unreacted substrate separated from the catalyst by filtration and decantation. The catalyst was extracted with CH2Cl2 and split for the next cycle. Results: Claisen–Schmidt condensation accomplished with reasonable to good yields, ranged from 78 to 95% at room temperature in the presence of the [L-AAIL], as compared to the traditional route at more than 100O C. Conclusion: [L-AAIL] are found a highly efficient and eco-friendly catalyst for synthesizing chalcone derivatives at room temperature. [L-AAIL] as a solvent and catalyst will exhibit real advantages by providing a ‘green’ process with the safer operation, Short reaction periods, mild reaction conditions, easier separation, and reusability of ionic liquid made this methodology valuable for synthetic organic chemists as well as industry.

Modeling and optimization of 2-Chlorophenol degradation using ultrasound assisted Fe3O4@TiO2: Central Composite Design-Genetic Algorithm approach

In this study, the ultrasound-catalyst hybrid system was applied for degradation of 2-chlorophenol (2-CP) from aquatic environment. The produced catalyst was characterized by transmission electron microscopy, scanning electron microscopy, X-ray scattering, vibration magnetometer and nitrogen adsorption/desorption analysis, showing the successful synthesize of the core-shell structure of magnetic TiO2. A Central Composite Design (CCD) was applied in MATLAB software to investigate the effective parameters in degradation and evaluate the removal of 2-CP by M-TiO2-US system. Kinetics, intermediate products and catalyst reusability were determined under optimal conditions. The results indicated that pH of 4.413, catalyst dosage of 0.733 g/L, 2-CP concentration of 2.549 mg/L, ultrasound power of 55.605 W/L had the maximum degradation efficiency (97.776 %) and pH was assigned as the most effective parameter for the degradation of 2-CP. Superoxide and hydroxyl radicals were considered as the main cause of 2-CP degradation. Catalyst stability was investigated in 5 replicates and verified. The overall results show that the M-TiO2 and US hybrid system has promising performance in the degradation of 2-chlorophenol and has the ability to use on a larger scale.