Kinetics of oxidation of ethyldigol by vanadium(V) in aqueous acidic medium

The kinetics of oxidation of ethyldigol by vanadium(V) in aqueous acidic medium has been carried out. The reaction is first order with respect to vanadium(V) and the substrate and is acid catalysed.Hammett acidity function (H ₀) andBunnett hypothesis have been applied. The formation of free radicals during the course of the reaction has been indicated. A probable reaction mechanism is proposed.

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Die Kinetik der Oxidation von Ethyldigol mit Vanadium(V) in wäßrigem saurem Medium

Zusammenfassung Es wurde die Kinetik der Oxidation von Ethyldigol mittels Vanadium(V) in wäßriger saurer Lösung untersucht. Die Reaktion ist erster Ordnung bezüglich Vanadium(V) und Substrat und ist säurekatalysiert. Es wurden dieHammett-Aciditätsfunktion (H ₀) und dieBunnett-Hypothese angewandt. Die Bildung von freien Radikalen während der Reaktion konnte bestätigt werden. Es wird ein Reaktionsmechanismus vorgeschlagen.

     

Role of solvent in the compatibility of a vinylchloride–vinylacetate–maleic acid terpolymer and nitrocellulose blends

The compatibility of cast films of a vinylchloride–vinylacetate–maleic acid terpolymer (VMCH) and nitrocellulose (NC) blends is influenced by solvents. Transparent films of VMCH/NC blends are obtained when cast from solvents such as tetrahydrofuran or cyclohexanone, whereas hazy films are obtained when cast from solvents such as acetone or ethylacetate. Visible spectroscopy and phase morphology were used to analyse the compatibility–incompatibility of the blend. Differential scanning calorimetry (DSC) studies demonstrate that the transparent film is compatible, but the hazy film is incompatible. Fourier transform infra-red (FTIR) studies establish that a greater interaction is observed between the polymer pair in case of the compatible blend than in the case of the incompatible blend. A solvent dependency of blend compatibility is reflected in this study. The conformational state of the polymers in solution, which is responsible for the compatibility phenomena, may depend on the donor number and/or Taft-β value of the solvent. The greater the donor number and/or the Taft-β value, the higher may be the level of interaction between the solvent and the polymer molecules, which in turn may give a compatible blend after removal of the solvent.     

Cu (II) and Co (II/III) complexes of N,O‐chelated Schiff base ligands: DNA interaction,protein binding,cytotoxicity, cell death mechanism and reactive oxygen species generation studies

A series of copper (II) ( 1 and 3 ) and cobalt (II/III) ( 2 , 4 and 5 ) complexes comprising different imino‐phenolate ligands DCH , DTH and DBH ₂ (where DCH = 2,4‐dichloro‐6‐((mesitylimino)methyl)phenol, DTH = 2,4‐di‐tert‐butyl‐6‐((mesitylimino)methyl) phenol and DBH ₂ = 2,4‐dibromo‐6‐((mesitylimino)methyl)phenol) have been prepared with excellent yield and high purity. By utilizing different spectroscopic tools such as UV–visible, electrospray ionization (ESI)‐mass, Fourier‐transform infrared (FTIR) spectrometry and elemental analysis, the prepared complexes ( 1 – 5 ) were thoroughly characterized. The molecular structure of the synthesized complexes was ascertained by using single‐crystal X‐ray diffraction studies (SCXRDs). The experiment reveals that Complexes 1 – 5 bind to calf thymus DNA (CT‐DNA) through non‐intercalative way with good interacting abilities. However, 1 – 5 are excellent quenchers of the fluorescence intensity of bovine serum albumin (BSA) following the static pathway. Additionally, they had shown remarkable cytotoxic potential against MCF‐7 (mammary gland adenocarcinoma) and A549 (lung adenocarcinoma) cell lines. The IC₅₀ values associated with these complexes were much lower than the conventional drug cisplatin. Apoptosis‐induced cell death was confirmed from the DNA fragmentation studies and Hoechst 33342 staining. The 2′,7′‐dichlorofluorescein diacetate (DCFDA) assay indicates that the complex mediated reactive oxygen species (ROS) generation is accountable for governing the apoptosis mechanism via oxidative cell distress. Apart from these studies, by carrying out density functional theory (DFT) method, highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap calculations and optimized structures of the synthesized complexes were accomplished.     

A Facile, Expeditious Route to the Benzooxabicyclo[3.2.1]octane System. Application to a Short, High-Yield Synthesis of Filiformin

A facile and efficacious route to the benzooxabicyclo[3.2.1]octane system has been developed and applied to a synthesis of filiformin (1). The cycloaddition of ethylene to the methoxychromone 13 furnished the oxetanol 14 through a tandem cycloaddition and gamma-hydrogen abstraction sequence. Lithium aluminum hydride reduction to the diol 15 followed by acid-catalyzed rearrangement produced benzooxabicyclooctanone (16), arising from exclusive external bond migration. Similarly, ethoxychromone (17) under the same sequence of reactions afforded the homologous bridged ketone 20. For the synthesis of filiformin (1), methoxychromone 24 on ethylene cycloaddition followed by reduction of resultant oxetanol 25 with lithium aluminum hydride furnished diol 10. Acid-catalyzed rearrangement of 10 provided the bridged ketone 11 which was brominated to give 26. This bromo ketone had previously been converted to filiformin (1), and also aplysin 9, and hence, the present work represents a short, high-yield formal synthesis of these sequiterpenes from a single starting material.     

Separation of enzymes from Candida boidinii crude extract by continuous flow zone electrophoresis.

Separation of the enzymes formate dehydrogenase, formaldehyde dehydrogenase and methanol oxidase from Candida boidinii crude extract has been explored using continuous flow zone electrophoresis in the VaP-22 and the scaled-up VaP-220 electrophoresis apparatus. Yields up to 95% and purification factors between 3 and 7 were obtained, together with separation of cell debris from the enzymes. Multiple injections of sample were used to obtain a protein throughput of 46.2 mg/h in the VaP-22. A tenfold higher throughput was achieved using the VaP-220. Correlation of the electrophoretic mobility in continuous flow zone electrophoresis with the elution behavior in ion-exchange chromatography confirmed the primary role of net surface charge in the separation of biological molecules. Proteins and enzymes with differences greater than 0.05 M elution molarities in ion-exchange chromatography can be separated. This corresponds to a preparative scale (mg/h or g/h) separation of proteins and enzymes whose difference in apparent electrophoretic mobility is greater than 0.70 x 10(-5) cm2/(V.s).     

Quantitative characterization and pharmaceutical compatibility between teneligliptin and widely used excipients by using thermal and liquid chromatography tandem mass spectrometry techniques

Journal of Thermal Analysis and Calorimetry - The aim of this work was to evaluate the quantitative characterization and pharmaceutical compatibility study of teneligliptin (TNG) with the commonly...     

Thermally Twistable,Photobendable, Elastically Deformable,and Self‐Healable Soft Crystals

The first example of a smart crystalline material, the 2:1 cocrystal of probenecid and 4,4′‐azopyridine, which responds reversibly to multiple external stimuli (heat, UV light, and mechanical pressure) by twisting, bending, and elastic deformation without fracture is reported. This material is also able to self‐heal on heating and cooling, thereby overcoming the main setbacks of molecular crystals for future applications as crystal actuators. The photo‐ and thermomechanical effects and self‐healing capabilities of the material are rooted in reversible trans–cis isomerization of the azopyridine unit and crystal‐to‐crystal phase transition. Fairly isotropic intermolecular interactions and interlocked crisscrossed molecular packing secure high elasticity of the crystals.     

Speciation and Multinuclear NMR Spectroscopic Studies of Di- and Trimethyltin(IV) Moieties with MESNA in Aqueous Medium

The interaction of Me₂Sn(IV)²⁺ and Me₃Sn(IV)⁺ with a prodrug, sodium 2-mercaptoethane sulfonate (HSCH₂CH₂SO₃Na, MESNA) abbreviated as (HL), has been studied potentiometrically in aqueous solution (I = 0.1 mol·L^?1 KNO₃, 298 K). The concentration distribution of various species formed in the solution was studied with changes in pH (~3–11). A strong coordination of MESNA with metal through the S atom of thiol group has been found. In the Me₂Sn(IV)–HL system, the species [Me₂Sn(L)]⁺ (53.1–75.6%) is predominant at acidic pH (3.73 ± 0.02) and the species [Me₂Sn(L)₂OH]^? (29.4–38.5%) is predominant at basic pH (10.32 ± 0.08). In contrast, for the Me₃Sn(IV)⁺ system, [Me₃SnL] (37.0–57.4%) is the major species at pH 7.65 ± 0.03 and [Me₃Sn(OH)] (49.9–67.2%) and [Me₃Sn(L)(OH)]^? (30.2–46.5%) are the major species at pH 11.05 ± 0.01. However, at physiological pH (7.01 ± 0.32), in both (1:1) and (1:2) Me₂Sn(IV)–HL systems, the species [Me₂Sn(L)(OH)] (67.2–89.9%) is predominant, whereas for Me₃Sn(IV)–HL (1:1) and (1:2) systems, [Me₃Sn(OH)] (53.5%) and [Me₃SnL] (56.8%) are the respective predominant species. In order to characterize the possible geometry of the proposed complex species, multinuclear (¹H, ¹³C and ¹¹⁹Sn) NMR studies were carried out at different pHs. No polymeric species were detected in the experimental pH range.