An Efficient Synthesis and Antimicrobial Studies of Bioactive 4H-1,4-Benzothiazine and Their Sulfone Derivatives

Abstract

4H-1,4-benzothiazines were prepared by condensation followed by oxidative cyclization of substituted 2-aminobenzenethiols with β-diketones in dimethylsulfoxide. On refluxing with 30% hydrogen peroxide in glacial acetic acid, 4H-1,4-benzothiazines yielded 4H-1,4-benzothiazine-1,1-dioxides. Structural evaluation has been done by spectral and elemental analysis. All the synthesized compounds were evaluated for their antibacterial and antifungal activity and all these have shown moderate to high activity against the test microbes.

Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional text, figures and tables.     

Dynamics of a droplet imbibing on a rough surface

We consider the imbibition of a liquid droplet of finite size on a rough surface and theoretically show that the imbibition dynamics is significantly slower than the familiar Washburn diffusive dynamics, ～t(0.5). The imbibition does not follow a simple power law. The droplet starts to imbibe with ～t(0.5) dynamics but progressively becomes slower with time. The slower imbibition is mainly attributed to the finite size of the droplet, resulting in a limited capillary driving force as compared to a steady capillary driving force in the case of imbibition from a steady source.     

Studies on preparation of 64Cu using (n,γ) route of reactor production using medium flux research reactor in India

⁶⁴Cu (t_1/2 12.7 h) is a versatile radionuclide owing to its unique decay scheme and exhibits three types of decay electron capture (41%), β⁻ (40%), β⁺ (19%) that is useful in nuclear medicine applications. Different batches of natural copper oxide (CuO) and 99.9% enriched ⁶³CuO targets were irradiated in research reactors at a neutron flux of 6.6 × 10¹² n cm⁻² s⁻¹ for duration of 3 days. Irradiated samples dissolved in hydrochloric acid solution were measured in HPGe-MCA system, the activity of ⁶⁴Cu, co-produced radionuclide impurities and radionuclide purity was determined. Average specific activity of 254 GBq ⁶⁴Cu per g Cu and ~348 GBq ⁶⁴Cu per g Cu was recorded at the end of irradiation from natural and enriched CuO targets, respectively.     

Palladium-catalyzed carbon-monoxide-free aminocarbonylation of aryl halides using N-substituted formamides as an amide source

A carbon-monoxide-free aminocarbonylation of various N-substituted formamides with aryl iodides and aryl bromides using palladium acetate and Xantphos is described. The developed methodology is applicable for a wide range of formamides and aryl halides containing different functional groups furnishing good to excellent yield of the corresponding products. N-substituted formamides are used as an amide source wherein a Vilsmeier-type intermediate plays a major role, thus eliminating the need of toxic carbon monoxide gas.     

Synthesis of nicotinonitrile derivatives and study of their photophysical properties

Abstract  

A convenient route was developed for the synthesis of novel nicotinonitrile derivatives by a three-component Dimroth reaction of chalcones, malononitrile, and secondary heterocyclic amines or sodium alcoholate. Nicotinonitrile derivatives are obtained in fair to good yields. The structures of all new compounds were established by spectroscopic characteristics and their photophysical properties were studied.     

An analytic perturbation approach for classical spinning particle dynamics

A perturbation method to analytically describe the dynamics of a classical spinning particle, based on the Mathisson–Papapetrou–Dixon (MPD) equations of motion, is presented. By a power series expansion with respect to the particle’s spin magnitude, it is shown how to obtain in general form an analytic representation of the particle’s kinematic and dynamical degrees of freedom that is formally applicable to infinite order in the expansion. Within this formalism, it is possible to identify a classical analogue of radiative corrections to the particle’s mass and spin due to spin–gravity interaction. The robustness of this approach is demonstrated by showing how to explicitly compute the first-order momentum and spin tensor components for arbitrary particle motion in a general space–time background. Potentially interesting applications based on this perturbation approach are outlined.     

Interpretation of temperature dependence of the in-plane electrical resistivity in YBa2Cu4O8: Electron–phonon approach

In this paper, we undertake a quantitative analysis of observed temperature-dependent in-plane normal state electrical resistivity of single crystal YBa₂Cu₄O₈. The analysis is within the framework of classical electron–phonon i.e., Bloch-Gruneisen model of resistivity. It is based on the inherent acoustic (low frequency) phonons (ω_ac) as well as high frequency optical phonons (ω_op), the contributions to the phonon resistivity were first estimated. The optical phonons of the oxygen breathing mode yields a relatively larger contribution to the resistivity compared to the contribution of acoustic phonons. Estimated contribution to in-plane electrical resistivity by considering both phonons i.e., ω_ac and ω_op, along with the zero-limited resistivity, when subtracted from single crystal data infers a quadratic temperature dependence over most of the temperature range [80 ? T ? 300]. Quadratic temperature dependence of ρ_diff. = [ρ_exp − {ρ₀ + ρ_e−ph (=ρ_ac + ρ_op)}] is understood in terms of electron–electron inelastic scattering. The relevant energy gap expressions within the Nambu-Eliashberg approach are solved imposing experimental constraints on their solution (critical temperature T_c). It is found that the indirect-exchange formalism provides a unique set of electronic parameters [electron–phonon (λ_ph), electron-charge fluctuations (λ_pl), electron–electron (μ) and Coulomb screening parameter (μ^*)] which, in particular, reproduce the reported value of T_c.     

Comparative Crystallographic and Hydrogen-bonding Analysis of Pregnane Derivatives

A crystallographic comparison comprised of some geometrical and structural features of a steroids series (pregnane derivatives) is made in the present paper. Some selected bond distances and bond angles of interest are discussed in detail. Conformations of individual ring systems in a series of 46 pregnane derivatives have been calculated and discussed. Correlation of ring conformations especially the rarer ones, vis-a-vis the multiple bonds and ring junctions has been discussed. Graphical presentations of ring conformations are made for all the five- and six-membered rings to show the relative frequency of their occurrence. 17β-side chain conformation is discussed in some pregn-20-one structures. X–H···A intra- and intermolecular interactions in the identified derivatives have been discussed with the standard distance and angle cut-off criteria. Distance-angle scatter plots for both kinds of interactions are presented for a better understanding of the packing interactions which exist in pregnane molecules.     

Synthesis and Structural Conformation Studies of a Potent Unsymmetrical 1,4-Dihydropyridine

Abstract 2,6-Dimethyl-5-(phenylcarbamoyl)-4-(3-nitrophenyl)-1,4-dihydropyridine-2-carboxylate was synthesized in two steps and was characterized spectroscopically and confirmed by X-ray diffraction studies. The molecule crystallizes in the monoclinic crystal class in the spacegroup P2₁/c with cell parameters a = 10.5960(6) ?, b = 10.2450(7) ?, c = 19.5790(11) ?, β = 107.448(3)° and Z = 4. The 1,4-dihydropyridine ring in the structure adopts a flattened boat conformation. Graphical Abstract 2,6-Dimethyl-5-(phenylcarbamoyl)-4-(3-nitrophenyl)-1,4-dihydropyridine-2-carboxylate was synthesized in two steps and was characterized spectroscopically and confirmed by X-ray diffraction studies. The molecule crystallizes in the monoclinic crystal class in the spacegroup P2₁/c with cell parameters a = 10.5960(6) ?, b = 10.2450(7) ?, c = 19.5790(11) ?, β = 107.448(3)° and Z = 4. The 1,4-dihydropyridine ring in the structure adopts a flattened boat conformation.      

Investigation of Euler spiral nanoantenna and its application in absorption enhancement of thin film solar cell

A theoretical study on nanoantenna and its application in enhancing the performance of the thin film solar cell (TFSC) is presented. In this work, a novel design of nanoantenna i.e. Euler spiral nanoantenna (ESNA) is introduced, which has evolved after bending the conventional dipole nanoantenna in the manner of Euler spiral. The bending is performed up to an optimum length so that the antenna can equally respond to the two orthogonally polarized waves. Then the proposed nanoantenna in turnstile manner is examined for the intended application of enhancing the absorption in TFSCs. The antenna is placed on the absorber layer (Si amorphous) of the TFSC with a coating of Zinc Oxide. The simulation results show that the proposed ESNA can significantly increase the absorption in the absorber layer of the TFSC. The performance in terms of absorption and quantum efficiency of the solar cell incorporated with ESNA has been studied. ESNA confines the electric field in a larger area which results in absorption increase. The simulation results show that proposed ESNA can enhance the absorption up to 97.6% in the absorber layer and the photocurrent is enhanced by a factor of 1.39. To the best of our knowledge, this is the first study on Euler spiral nanoantenna and so as in its application with solar cells.