Standardization of Biomarkers Gallic Acid and Berberine in Polyherbal Formulation Entoban Capsules by High-Performance Thin-Layer Chromatography—Densitometry

JPC – Journal of Planar Chromatography – Modern TLC - The technological improvement in the structural elucidation of natural compounds has made it probable to generate appropriate...     

Numerical solutions to initial and boundary value problems for linear fractional partial differential equations

In this article, Haar wavelets have been employed to obtain solutions of boundary value problems for linear fractional partial differential equations. The differential equations are reduced to Sylvester matrix equations. The algorithm is novel in the sense that it effectively incorporates the aperiodic boundary conditions. Several examples with numerical simulations are provided to illustrate the simplicity and effectiveness of the method.     

Grob-type fragmentation of 5-oxabicyclo[2.1.1]hexane system: a strategy for synthesis of annulated and 2,2,5-trisubstituted tetrahydrofurans

Acid mediated, efficient Grob-type fragmentation reaction facilitated by vicinal ketal and ester moieties in variety of 5-oxabicyclo[2.1.1]hexanes leading to the corresponding annulated and 2,2,5-trisubstituted tetrahydrofurans is reported. Among the Brønsted and Lewis acids tested, BF₃·OEt₂ appears to give the best results, furnishing near quantitative yield (>99%) of tetrahydrofuran tricarboxylate derivatives under mild reaction condition. In case of unsymmetrical monosubstituted 5-oxabicyclo[2.1.1]hexanes two regioisomeric products are obtained. A strategy to transform one of the ester groups of the title compounds to protected hydroxymethyl moiety was evolved, which allows access to differentially protected 2-hydroxymethyl THF derivatives upon fragmentation. Employing TiCl₄/R or S-BINOL as chiral Lewis acid, an enantioselective fragmentation (up to 66% ee) was described for the meso bis-furan derivative.     

Synthesis,XRD, spectral (IR,UV–Vis,NMR) characterization and quantum chemical exploration of benzoimidazole‐based hydrazones: A synergistic experimental‐computational analysis

Present study advocates the joint experimental and computational studies of two potent benzoimidazole‐based hydrazones with chemical formula C₂₃H₁₈F₂N₄O ( 5a ) and C₂₅H₂₂FN₅O₃ ( 5b ). Both 5a and 5b were synthesized and resolved into their crystal structures using SC‐XRD for the assessment of bond lengths, bond angles, unit cells and space groups. The structures of 5a and 5b were chemically characterized using infrared (FT‐IR), UV–Visible, nuclear magnetic resonance (¹H‐NMR and ¹³C‐NMR), EIMS and elemental analysis. DFT at M06‐2X/6‐31G(d,p) level of theory was performed to get optimized structures and countercheck the experimental findings. Overall, DFT findings show excellent concurrence with the experimental data which confirms the purity of both compounds. FMO, NBO analysis, MEP surfaces and nonlinear optical (NLO) properties were explored at same level of theory. UV–Vis analysis at TDDFT/M06‐2X/6‐31G(d,p) level of theory showed that 5b is red shifted with λ_max 331.69 nm as compared to 5a with λ_max 240.25 nm. Global reactivity parameters were estimated using energy of FMOs indicated the greater harness value than the softness values of 5a and 5b . NBO analysis confirmed that the presence of non‐covalent interactions, hydrogen bonding and hyper conjugative interactions are pivotal cause for the existence of 5a and 5b in the solid‐state. NLO results of 5a and 5b were observed better than standard molecule recommended the NLO activity of said molecules for optoelectronic applications.     

Kinetics of silver nanoparticle growth in aqueous polymer solutions: 1st Nano Update

In this paper we report the effect of poly(vinyl alcohol) (PVA) on the silver nanoparticles formation of different morphologies by using silver nitrate and citric acid as the oxidant and reductant, respectively, for the first time. Our transmission electron microscopy (TEM) results suggest that the presence of PVA has significant impact on the size, shape, and the size distribution of the silver nanoparticles. The reaction follows a zero-order kinetics in [citric acid] as well as in [silver(I)] in the absence and presence of PVA. It was found that PVA and cetyltrimethylammonium bromide (CTAB) concentrations show no significant effects on the rate of CTAB-stabilized silver nanoparticles formation, whereas in presence of PVA, the reaction rate increases with (CTAB). Both spectrophotometric and TEM measurement demonstrated that the orange silver sol consists of aggregates, whereas the purple sol does not contain the aggregated arrangement. On the basis of various observations, the most plausible mechanism has been envisaged.     

Automatic Debye–Scherrer elliptical ring extraction via a computer vision approach

The accurate calibration of powder diffraction data acquired from area detectors using calibration standards is a crucial step in the data reduction process to attain high‐quality one‐dimensional patterns. A novel algorithm has been developed for extracting Debye–Scherrer rings automatically using an approach based on computer vision and pattern recognition techniques. The presented technique requires no human intervention and, unlike previous approaches, makes no restrictive assumptions on the diffraction setup and/or rings. It can detect complete rings as well as portions of them, and works on several types of diffraction images with various degrees of ring graininess, textured diffraction patterns and detector tilt with respect to the incoming beam.     

Metallogels Self‐Assembled from Linear Rod‐Like Platinum Complexes: Influence of the Linkage

Two linear rod‐like platinum complexes, which only differed in the linkage, were prepared. They both self‐assemble into metallogels in nonpolar solvents; however, a very big contrast was observed. Unexpectedly, a much weaker gel was acquired upon replacing the ester linkage by an amide group. The intermolecular hydrogen bonding offered by the amide motif leads to a different stacking fashion and mechanism. The results demonstrated herein contribute to the rational design of metallogels as well as other functional supramolecular materials.