Suzuki–Miyaura cross-coupling reaction assisted by palladium nanoparticles-decorated zeolite 13X nanocomposite: a greener approach

Heterogeneous catalysts govern the field of catalysis due to their easy separation from a reaction mixture, reusability, and prevention of agglomeration, making them more efficient catalysts than homogeneous catalysts. Herein, we report the eco-friendly synthesis of a novel heterogeneous catalyst, viz. palladium nanoparticles (Pd NPs) decorated over zeolite 13X nanocomposite using dried fruits of Terminalia chebula Retz. as the reducing and stabilizing agent and its performance as a promising catalyst for the Suzuki–Miyaura coupling reactions. The particle size, crystallinity, morphology, and textural properties of the catalyst were identified using Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) analysis which confirmed the presence of palladium nanoparticles on the surface of zeolite 13X. The FESEM images revealed the presence of spherical-shaped Pd NPs over the cubical particles of zeolite 13X. The average particle size of the palladium nanoparticles was found to be in the range of 6–7 nm and was polycrystalline in nature. From BET analysis, it was inferred that the decoration of Pd NPs decreased the surface area of zeolite 13X (615.5 m²/g to 548.334 m²/g), thus leaving pores unoccupied. This study showed the efficiency of this novel catalyst in the formation of biaryl derivatives using low palladium loadings (0.0012 mol%) giving good to excellent yields (90–99%) within short reaction times (10–225 min) with high TONs (>?79,000) and TOFs (>?21,000). Both electron-donating and electron-withdrawing aryl halides and aryl boronic acids reacted smoothly in the presence of K₂CO₃ as a base and EtOH/H₂O (1:1) as the solvent. Besides, the catalyst could be recycled and reused for 5 consecutive runs with minimal loss of its efficiency. The supremacy of this catalyst could well be exploited in future for various organic transformations.

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Triphenyltelluronium β-diketonates; Synthesis and spectra

Triphenyltelluronium /gb-diketonates, RC(O)CHC(O)R¹ (where R = CH₃, Ph or CF₃ and R¹ = CH₃, Ph, CF₃ or 2-thienyl) have been prepared. Spectral data(IR, ¹H and ¹³C NMR, mass spectroscopy) are presented and discussed in conjunction with molecular weight and conductivity data. It is concluded that weak coordination of the β-diketonate to the tellurium atom is a common structural feature of the compounds.     

Systematics of the librational modes of water in the IR spectra of MSO4 · H2O (M = Mn,Co, Ni,Zn)

In the isomorphous hydrates MSO₄ · H₂O (M = Mn, Co, Ni, Zn), where M-O_W distance is the only variable, the frequencies of the wagging, rocking and bending modes of water and of metal-oxygen stretching have been shown to correlate smoothly with the distance r(M-O_W). Quantitative relations have been found for ν_W and ν(M-O_W) which vary linearly, while ν_R and ν^C₂ vary non-linearly with r(M-O_W).     

Asymptotic screened hydrogenic radial integrals

The screened hydrogenic radial dipole integral for discrete-discrete transitions from initial state n'l' to final state nl is asymptotically expanded to the lowest order such that the final quantum number n --> infinity. The analytical expression obtained is in terms of confluent hypergeometric functions, and explicit expressions for a few of the specific transitions are derived from them as examples.     

Analysis of ibuprofen,pantoprazole, and itopride combination therapeutic drugs in human plasma by solid phase membrane microtip extraction and high-performance liquid chromatography methods using new generation core shell C18 column

Iron nanocomposite adsorbent was synthesized by green technology with 90% yield. The surface was amorphous and irregular in nature. The iron nanocomposite adsorbent was applied in solid phase membrane microtip extraction (SPMMTE) procedure for the extraction of ibuprofen, pantoprazole, and itopride drugs. SPMMTE was used to extract these drugs from plasma. SunShell C₁₈ column was used with phosphate buffer (10 mM, pH 7.0):acetonitrile (70:30, v/v) as mobile phase at 1.0 mL min^?1 flow rate with a detection at 220 nm. The retention factor values were 2.23, 3.25, and 5.38. The values of separation and resolution factors were 1.41 and 1.65, and 5.00 and 12.14, respectively. The percentage recoveries were ibuprofen (90%), pantoprazole (80%), and itopride (75%) in standard solution. The reported SPMMTE and HPLC methods were fast, inexpensive, specific, precise, accurate, and robust for the analysis of the reported drugs. These results indicated that the reported nanocomposite adsorbent-based SPMMTE and HPLC methods may be used to monitor the reported drugs in any unknown matrices.     

Siderophoregenic Bradyrhizobia boost yield of soybean

After screening for siderophore (microbial iron chelator) production, of seven available cultures of soybean (Glycine max L.) root nodule bradyrhizobia, one strain, Bradyrhizobium japonicum NCIM 2746, was selected to confirm its phytopathogenic suppression and soybean growth promotion. Based on chromatographic and spectrophotometric studies, two different siderophores, a hydroxamate type (MW 734) and another catecholate type (MW 1000), were observed. Randomized block design (RBD) analysis of sickpot studies (soil inoculated with phytopathogens) with an MACS 124 variety of soybean, bacterized with siderophoregenic B. japonicum, showed a marked increase in the percentage of germination, nodulation, chlorophyll, oil, protein content, and number of pods. Field trial study confirmed these pot results, which were evident from enhancement in shoot length, number of branches, chlorophyll content, number of nodules, root length, and number of pods. These results suggest the possibility of exploiting B. japonicum NCIM 2746 as a potential bioinoculant.     

Thermal weight functions for bi-material interface crack system using energy principles

In this study, Betti’s reciprocal theorem and the principle of superposition are used to obtain weight functions in a two-dimensional bi-material interface crack system for any loading, in general and thermal loading, in particular. It is shown that the general expression of weight functions for bi-materials interface crack problems is of the same type as that found in a homogeneous mixed mode loading case. Furthermore, a computational approach has been developed for calculation of thermal stress intensity factors for bi-material interface cracks subjected to thermal loading under quasi-static uncoupled thermo-elasticity assumption. The thermal weight function (TWF) expression and computational scheme have been validated using three examples given in the available literature.