Group 12 metal monoselenocarboxylates: synthesis, characterization, structure and their transformation to metal selenide (MSe; M = Zn, Cd, Hg) nanoparticles

Reactions of [MCl2(tmeda)] with potassium salts of monoselenocarboxylic acids gave complexes of the general formula [M(SeCOR)2(tmeda)] (M = Zn, Cd; R = Ph, Tol; Tol = C6H4-p-CH3; tmeda = Me2NCH2CH2NMe2). The analogous mercury complexes were unstable at room temperature and afforded HgSe nanoparticles during the course of reaction. All the complexes were characterized by elemental analysis, IR, UV-vis, NMR (1H, 13C, 77Se, 113Cd) data. The X-ray structural analysis of [Cd(SeCOPh)2(tmeda)] revealed that the complex is a discrete monomer having an approximate tetrahedral coordination environment around the central metal atom with monodentate (Se-bonded) selenocarboxylates. Thermal behavior of these complexes was studied by TG analysis. Pyrolysis in a furnace or in HDA (hexadecylamine) gave MSe nanoparticles, which were characterized by XRD, EDAX, SEM and absorption spectroscopy.     

Synthesis and antimicrobial activity of 2<Emphasis Type="Italic">H</Emphasis>-pyrimido[2,1-<Emphasis Type="Italic">b</Emphasis>]benzothiazol-2-ones

4-Phenyl-2H-pyrimido[2,1-b]benzothiazol-2-ones have been synthesized in quantitative yields by the reaction of 2-aminobenzothiazoles with alkynoic acid. The antimicrobial activity of the synthesized compounds was tested against bacterial species, Bacillus coagulans, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa. The synthesized compounds have shown significant activity against microorganisms which can be correlated with the fused heterocyclic systems.     

β-Functionalized ethylchalcogenolate complexes of lead(II): Synthesis, structures and their conversion into lead chalcogenide nanoparticles

The reactions of Pb(OAc)₂·3H₂O with NaER yield homoleptic colorless to yellow complexes of composition, [Pb(ER)₂] (ER = SCH₂CH₂NMe₂ (1), SeCH₂CH₂NMe₂ (2) and SeCH₂CH₂COOMe (3)). These complexes were characterized by elemental analyses, UV–Vis and ¹H NMR data. Molecular structures of [Pb(ECH₂CH₂NMe₂)₂] (E = S or Se) have been established by single crystal X-ray diffraction analyses. These molecules have a distorted trigonal bipyramidal configuration around lead with the nitrogen atoms of the chelating chalcogenolate ligands occupying the axial positions. Thermal behavior of these complexes was studied by TG analysis. Pyrolysis in a furnace or in HDA (hexadecylamine) gave PbE nanoparticles which were characterized by UV–Vis, photoluminescence, XRD, EDAX, and TEM measurements.     

Elimination of limit cycles in a class of digital filters using single saturation nonlinearity

Using Lyapunov's direct method, a novel frequency-domain criterion for the elimination of limit cycles in a class of digital filters using single saturation nonlinearity is derived. The criterion turns out to be a generalization and improvement over an earlier criterion due to Kar and Singh. An example showing the effectiveness of the criterion is given. A graphical interpretation of a simplified version (involving one free parameter) of the criterion is discussed.     

A comparative study of phase-shifting algorithms in digital speckle pattern interferometry

Digital speckle pattern interferometry (DSPI) is a tool for making qualitative as well as quantitative measurements of deformation of objects. Phase-shifting algorithms in DSPI are useful for extracting quantitative deformation data from the system. Comparative studies of the different phase-shifting algorithms in DSPI for object deformation measurement are presented. Static and quasi-dynamic deformation of the object can be measured using these algorithms. Error compensating five-step phase-shifting method is used for the algorithms.     

Facile and efficient preparation of hybrid phenylthiazolyl-1,3,5-triazines and their antidepressant-like effect in mice

High safety, robust efficacy, and rapid onset of action remain the key challenges for improving antidepressant drug discovery. We report a facile and efficient synthetic strategy to structurally encompass mono-, di-, or tri-substituted derivatives using cyanuric chloride and various substituted phenylthiazole-2-amines. The predicted physicochemical property precisely state their specificity as CNS acting agent and antidepressant-like effect of the most promising compound 10 after oral administration significantly reduced immobility in mice behavior models, especially TST from 63 s. In addition, good safety features of 10 highlight its ability to modulate hallmarks for antidepressant discovery. These insights are useful in generalization and systematization of CRF₁ antagonist design to develop future biological end points.     

Sintering kinetic study of the nano-crystalline 3-mol% yttria-samaria codoped tetragonal zirconia polycrystal ceramics

Dilatometric shrinkage data was utilized to study the sintering kinetics of the in-house synthesized nano-crystalline 3-mol% yttria-samaria codoped tetragonal zirconia polycrystal (TZP) ceramics. The objective was to determine activation energy (Q) of sintering and the sintering mechanism (n) relevant to the initial stage of sintering. The product of activation energy and sintering parameter, i.e., “nQ” was calculated from the shrinkage data acquired from the constant rate of heating experiment. The apparent activation energy of sintering (Q) was calculated using modified-“Dorn” method. Modified Johnson’s equation was used to determine value of “n” using the activation energy obtained from the Dorn method. Stepwise isothermal dilatometry technique was utilized as an independent method to determine the “n” value. The activation energy of sintering was in the range of 400–525 kJ mol^?1 and found to be dependent on the dopant concentration. The value of “n” was found to be ~0.33 for both 3 mol% yttria-doped (3Y-TZP) and yttria-samaria codoped (3(Y,S)-TZP) TZP, whereas for 3 mol% samaria-doped tetragonal zirconia (3S-TZP), the value of “n” was ~0.40. From the obtained “n” values, it may be concluded that grain boundary diffusion (GBD) was the dominant sintering mechanism in 3Y-TZP and 3(Y,S)-TZP, whereas an intermediate of GBD and volume diffusion influences the initial sintering stage in the 3S-TZP.     

Short Chemoenzymatic Total Synthesis of ent‐Hydromorphone: An Oxidative Dearomatization/Intramolecular [4+2] Cycloaddition/Amination Sequence

A short synthesis of ent‐hydromorphone has been achieved in twelve steps from β‐bromoethylbenzene. The key transformations involved the enzymatic dihydroxylation of the arene to the corresponding cis‐dihydrodiol, Mitsunobu coupling with the ring A fragment, oxidative dearomatization of the C3 phenol, and the subsequent [4+2] cycloaddition to form ring B of the morphinan. The synthesis was completed by intramolecular amination at C9.     

Synthesis,Characterization, and X-Ray Structures of 2-(3,5-Dimethylpyrazol-1-Yl)Phenyl-Based Organoselenium Compounds and Their Glutathione Peroxidase (Gpx) Like Activity

Abstract

The synthesis of a series of 2-(3,5-dimethylpyrazol-1-yl)phenyl-based organoselenium compounds, (dmpzC₆H₄Se)₂ (1), dmpzC₆H₄SeR (dmpz = 3,5-dimethylpyrazol-1-yl; R = (CH₂)_nY; Y = OH, NH₂, and COOH), and dmpzC₆H₄SeX (X = Cl, Br, or I) is described. The compounds are characterized by IR, NMR (¹H, ¹³C{¹H}, ⁷⁷Se{¹H}), and mass spectral (MS) data. The molecular structures of (dmpzC₆H₄Se)₂, dmpzC₆H₄SeCH₂COOH, and dmpzC₆H₄SeCH₂CH₂OH have been established by X-ray crystallography. The two latter compounds are associated in the solid state through intermolecular hydrogen bonding between the OH proton and the pyrazolyl nitrogen atom of the adjacent molecule. Glutathione peroxidase (GPx) like catalytic activity of these compounds has been evaluated by using hydrogen peroxide (H₂O₂) as substrate and dithiothreitol (DTT^red) as thiol cofactor in CD₃OD, and the progress of the reaction was monitored by ¹H NMR spectroscopy. All the compounds exhibited the GPx-like catalytic activity. Among these, the ones containing alkylamino groups showed the best activity.

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