One-Pot Sustainable Synthesis of Highly Substituted Pyrimidines via Acceptorless Dehydrogenative Annulation of Alcohols Using Pincer Ni(II)-NNS Catalysts

We report an efficient and sustainable synthesis of highly substituted pyrimidines promoted by nickel(II)-NNS pincer-type complexes via acceptorless dehydrogenative annulations of readily available alcohols, malononitrile, and guanidine/benzamidine salt under eco-friendly conditions for the first time. Different sets of Ni(II) complexes (C1-C3) encapsulated in NNS pincer-type thiosemicarbazone ligands have been synthesized and authenticated by analytical and spectroscopic (Fourier transform infrared, nuclear magnetic resonance, and high-resolution mass spectrometry) techniques. The solid state three-dimensional structure of a representative complex (C2) has been determined with the aid of single crystal XRD analysis and confirms a square planar architecture around the nickel ion. Further, the well-defined Ni(II) complexes have been employed as efficient catalysts for the fabrication of a wide range of 4-aminopyrimidine-5-carbonitrile derivatives (33 examples) from readily available alcohols with suitable coupling partners such as malononitrile and guanidine/benzamidine under eco-friendly conditions. The current catalytic approach affords maximum yields up to 95% utilizing 3 mol % catalyst loading and water/hydrogen as the only byproduct. A feasible catalytic pathway has been proposed based on the different control experiment reactions, which clearly indicate that the coupling reaction proceeds via aldehyde and benzylidenemalononitrile intermediates. The practicability of the current protocol has been demonstrated by the large-scale synthesis of one of the products, 4-amino-2,6-diphenylpyrimidine-5-carbonitrile, and a short synthesis of a cytosine antifungal analogue.

Ultrasound-assisted synthesis of pyrimidines and their fused derivatives: A review

The pyrimidine scaffold is present in many bioactive drugs; therefore, efficient synthetic routes that provide shorter reaction times, higher yields, and site-selective reactions are constantly being sought. Ultrasound (US) irradiation has emerged as an alternative energy source in the synthesis of these heterocyclic scaffolds, and over the last ten years there has been a significant increase in the number of publications mentioning US in either the construction or derivatization of the pyrimidine core. This review presents a detailed summary (with 140 references) of the effects of US (synergic or not) on the construction and derivatization of the pyrimidine core through classical reactions (e.g., multicomponent, cyclocondensation, cycloaddition, and alkylation reactions). The main points that were taken into consideration are as follows: chemo- and regioselectivity issues, and the results of conventional heating methods compared to US and mechanistic insights that are also presented and discussed for key reactions.

Kinetics and Equilibrium of Radioactive Metal Adsorption onto Sugarcane Bagasse Waste: Comparison of Batch and Column Adsorption Modes

Sugarcane bagasse waste biomass (SBWB) efficacy for the adsorption of Zr(IV) was investigated in batch and column modes. The process variables i.e. pH 1–4 (A), adsorbent dosage 0.0–0.3 g (B), and Zr(IV) ions initial concentration 25–200 mg/L (C) were studied. The experiments were run under central composite design (CCD) and data was analysed by response surface methodology (RSM) methodology. The factor A, B, C, AB interaction and square factor A2, C2 affected the Zr(IV) ions adsorption onto SBWB. The quadratic model fitted well to the adsorption data with high R2 values. The effect of bed height, flow rate and Zr(IV) ions initial concentration was also studied for column mode adsorption and efficiency was evaluated by breakthrough curves as well as Bed Depth Service and Thomas models. Bed height and Zr(IV) ions initial concentration enhanced the adsorption of capacity of Zr(IV) ions, whereas flow rate reduced the column efficiency.

Effect of Hydrothermal Reaction Time on Electrical, Structural and Magnetic Properties of Cobalt Ferrite

Cobalt ferrite was synthesized by hydrothermal route in order to investigate the effect of hydrothermal reaction time on structural, magnetic and dielectric properties. The synthesized cobalt ferrite was characterized by X-ray diffraction, Fourier transform infrared and Vibrating-Sample Magnetometer (VMS). XRD data analysis confirmed the formation of cubic inverse spinel ferrite for complete time series as the high intensity peak corresponds to cubic normal spinel structure. The ionic radii, cation distribution among tetrahedral and octahedral sites, lattice parameters, X-ray density, bond lengths were also investigated cobalt ferrite prepared at different hydrothermal reaction time. The crystallite size was found to be in the range of 11.79–32.78 nm. Tolerance factor was near unity that also confirms the formation of cubic ferrites. VSM studies revealed the magnetic nature of cobalt ferrite. The coercivity (1076.3Oe) was observed for a sample treated for 11 h. The squareness ratio was 0.56 that is close to 0.5 which shows uniaxial anisotropy in cobalt ferrite. Frequency dependent dielectric properties i.e. dielectric constant, AC conductivity, tangent loss and AC resistivity are calculated with the help of Impedance Analyzer. Intrinsic cation vibration of cubic spinel ferrites are confirmed from FTIR analysis in the range of 400–4000 cm−1. In view of enhanced properties, this technique could possibly be used for the synthesis of cobalt ferrite for different applications.

Gamma Radiation and Hydrogen Peroxide Based Advanced Oxidation Process for the Degradation of Disperse Dye in Aqueous Medium

In view of promising efficiency of advanced oxidation process (AOP), gamma radiation in combination with H2O2 was employed for the degradation of disperse red 73 (DR73) dye. Cs-137 gamma radiation source was used for dye aqueous solution irradiation. The process variables such as pH (3–9), H2O2 concentration (0.3–0.9 mL), gamma radiation absorbed dose (1–20 kGy) and DR73 initial concentration (50–150 mg/L) were optimized for maximum degradation of dye. The efficiency of AOP was evaluated on the basis of dye degradation, water quality parameters and toxicity reduction. Degradation of DR73 was achieved 69% using gamma radiation absorbed dose of 20 kGy and at the same dose 96.3% degradation was achieved in the presence of 0.9 mL/L H2O2. The dye degradation found to be dependent on dye initial concentration and pH of the medium. The radiolytic progress of DR73 was monitored by Fourier transform infrared (FTIR) and UV-Visible spectroscopy. The chemical oxygen demand (COD) and biological oxygen demand (BOD) were reduced significantly in response of treatment of dye at optimum conditions of process variables. The toxicity of treated and un-treated dye solution was monitored by haemolytic and Ames assays. Results revealed that the toxicity of DR73 dye was also reduced significantly after treatment. Findings revealed that the gamma radiation based AOPs are promising and could possibly be used for the remediation of textile wastewater contains toxic dyes.

Green Synthesis of Metal Nanoparticles and their Applications in Different Fields: A Review

Nanotechnology is an art for application and handling of materials at very small scales i.e. 1–100 nm. The materials at this scale exhibit significantly different properties compared to same materials at larger scales. There are so many physical and chemical methods for the synthesis of nanoscale materials but the most appropriate are the ones that synthesize materials using green chemistry eco-friendly techniques. Recently, the collaboration between nanotechnology and biology has opened up new horizons of nanobiotechnology that integrates the use of biological materials in a number of biochemical and biophysical processes. This approach has significantly boosted up nanoparticles (NPs) production without employing harsh and toxic conditions and chemicals. This review is aimed to provide an outline of latest developments in synthesis of NPs through biotic entities and their potential applications.

UV/H2O2/Ferrioxalate Based Integrated Approach to Decolorize and Mineralize Reactive Blue Dye: Optimization Through Response Surface Methodology

The decolorization and mineralization of Reactive Blue 222 dye was studied using UV/H2O2/ferrioxalate approach in combination with Pleorotus ostreatus. The dye was decolorized by UV/H2O2/ferrioxalate based advanced oxidation process (AOP) at different levels of process variables dye concentration, catalyst dose, pH, reaction time and resultantly, 80% decolorization was achieved. Pleorotus ostreatus treatment enhanced the dye degradation up to 92% at optimum levels of pH, temperature, inoculum size, carbon and nitrogen sources at specific concentration. Response Surface Methodology (RSM) was employed for optimization under face-centered central composite design (CCD). Although both treatments were found efficient for the removal of dye, but on applying the integrated approach, 96% dye removal was obtained which led to complete degradation of the dye. FTIR analysis confirmed the degradation of dye into low mass compounds. The water quality assurance parameters were measured to assess the mineralization efficiency. A significant reduction in COD (94%) and TOC (92%) were found when dye was degraded integrated approach. A phytotoxicity analysis on Pisum sativum plant revealed the non-toxic behavior of metabolites produced. Results revealed that the integrated approach is highly promising for the decolorization and mineralization of the Reactive Blue 222 dye and is also extendable to treat the dye in textile wastewater.

Structural and Optical Properties of Multilayer Heterostructure of CdTe/CdSe Thin Films

CdTe/CdSe multilayer heterostructures thin films were prepared by thermal evaporation method. The CdTe/CdSe layers deposited on glass substrate and effects of annealing temperature on optical and structural properties of thin films were investigated. The XRD analysis revealed that CdTe and CdSe were in cubic (111) and hexagonal (100) forms. By increasing the annealing temperature, intensity of XRD peaks increased for multilayer heterostructures. Band alignment in heterostructures of CdTe/CdSe was of type II. Energy band gaps values for CdTe/CdSe multilayer heterostructures increased with respect to bulk compounds. During emission, red and blue shifts are observed in visible region in photoluminescence spectrum of CdTe/CdSe samples. Due to better crystallinity of multilayer thin film, 1LO, 2LO and 3LO phonon modes were observed in Raman spectrum.