Synthesis, characterization and pharmacological activities of 2-[4-cyano-(3-trifluoromethyl)phenyl amino)]-4-(4-quinoline/coumarin-4-yloxy)-6-(fluoropiperazinyl)-s-triazines

A series of 2-[4-cyano-(3-trifluoromethyl)phenyl amino)]-4-(4-quinoline/coumarin-4-yloxy)-6-(fluoropiperazinyl)-s-triazines has been synthesized by a simple and efficient synthetic protocol. The antimicrobial activity of the compounds was studied against several bacteria (Staphylococcus aureus MTCC 96, Bacillus cereus MTCC 619, Escherichia coli MTCC 739, Pseudomonas aeruginosa MTCC 741, Klebsiella pneumoniae MTCC 109, Salmonella typhi MTCC 733, Proteus vulgaris MTCC 1771, Shigella flexneria MTCC 1457) and fungi (Aspergillus niger MTCC 282, Aspergillus fumigatus MTCC 343, Aspergillus clavatus MTCC 1323, Candida albicans MTCC 183) using paper disc diffusion technique and agar streak dilution method. Newly synthesized compounds were also tested for their in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv using BACTEC MGIT and Lowenstein-Jensen MIC method.     

Solid state white light emitting systems based on CeF3: RE3+ nanoparticles and their composites with polymers

A series of doped CeF(3): RE(3+) (RE(3+): Tb(3+), Eu(3+) and Dy(3+)) nanoparticles were synthesized, with the aim of obtaining a white light emitting composition, by a simple polyol route at 160°C and characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence. Uniformly distributed and highly water-dispersible rectangular nanoparticles (length ~15-20 nm, breadth ~5-10 nm) were obtained. The steady state and time resolved luminescence studies confirmed efficient energy transfer from the host to activator ions. Lifetime studies revealed that optimum luminescence is observed for 2.5 mol% Dy(3+) and 7.5 mol% Tb(3+). The energy transfer efficiencies (Ce(3+) to activators) were found to be 89% for CeF(3): Tb(3+) (7.5 mol%) nanoparticles and 60% for CeF(3): Dy(3+) (2.5 mol%) nanoparticles. Different concentrations of Tb(3+), Eu(3+) and Dy(3+) were doped to achieve a white light emitting phosphor for UV-based LEDs (light emitting diodes). Finally CeF(3), triply doped with 2.0 mol%Tb(3+), 4.5 mol% Eu(3+) and 3.5 mol% Dy(3+), was found to have impressive chromaticity co-ordinates, close to broad day light. The colloidal solutions of doped CeF(3) nanoparticles emitted bright green (Tb(3+)), blue (Dy(3+)) and white (triply doped) luminescence upon host excitation. Composites of poly methyl methacrylate (PMMA) and poly vinyl alcohol (PVA) were made with CeF(3): 5.0 mol%Tb(3+), CeF(3): 5.0 mol% Dy(3+) and triply doped white light emitting composition. The CeF(3)/PMMA (PVA) nanocomposite films, so obtained, are highly transparent (in the visible spectral range) and exhibit strong photoluminescence upon UV excitation.     

Structural, magnetic, and gas adsorption study of a series of partially fluorinated metal-organic frameworks (HF-MOFs)

Four new partially fluorinated metal organic frameworks (HF-MOFs) have been synthesized under different solvothermal conditions (H(2)O or dimethylformamide (DMF)) from transition metal cations [Co(2+) and Mn(2+)], 3-methyl pyridine (3-mepy) and 4,4'-(hexafluoroisopropylidene) bis(benzoic acid) (C(17)H(10)F(6)O(4), H(2)hfbba), to determine the influence of reaction conditions on the formation of MOFs. This family of materials displays a striking degree of structural similarity depending on the solvent of synthesis. HF-MOFs synthesized from H(2)O [Co-HFMOF-W, Co(hfbba)(3-mepy)(H(2)O) and Mn-HFMOF-W, Mn(hfbba)(3-mepy)(H(2)O)] contain three-dimensional connectivity whereas HF-MOFs synthesized from DMF Co-HFMOF-D, [Co(2)(hfbba)(2)(3-mepy)(2)]·(DMF)(3) and Mn-HFMOF-D, [Mn(2)(hfbba)(2)(3-mepy)]·(H(2)O) are two-dimensional in nature. Co-HFMOF-W and Mn-HFMOF-W are iso-structural polymeric materials. Thermal gravimetric analysis performed on as-synthesized HF-MOFs revealed that these compounds have high thermal stability (～350 °C). The continuous decrease of the χT product with decreasing T for Co-HFMOF-D and Co-HFMOF-W respectively indicates the presence of antiferromagnetic exchange interaction between two Co(2+) (S = 3/2) metal centers within a cluster.     

Electronic structure, molecular electrostatic potentials, vibrational spectra in substituted calix[n]arenes (n = 4, 5) from density functional theory

Electronic structure, molecular electrostatic potential, and vibrational frequencies of para-substituted calix[n]arene CX[n]-R (n = 4, 5; R = H, NH(2), t-Bu, CH(2)Cl, SO(3)H, NO(2)) and their thia analogs (S-CX[n]-R; with R = H and t-Bu) in which sulfur bridges two aromatic rings of CX[n] have been derived from the density functional theory. A rotation around CH(2) groups connecting the phenol rings engenders four, namely, cone, partial cone, 1,2-alternate, and 1,3-alternate CX[n]-R conformers. Of these, the cone conformer comprising of large number of O1-H1···O1' interactions turns out to be of lowest energy. Normal vibration analysis reveal the O1-H1 stretching frequency of unsubstituted CX[n] shifts to higher wavenumber (blue shift) on substitution of electron-withdrawing (NO(2) or SO(3)H) groups, while electron-donating substituents (NH(2), t-Bu) engender a shift of O1-H1 vibration in the opposite direction (red shift). The direction of frequency shifts have been analyzed using natural bond orbital analysis and molecular electrostatic potential (MESP) topography. Furthermore, calculated (1)H NMR chemical shift (δ(H)) in modified CX[n] hosts follow the order: H1 > H3/H5 > H7(a) > H7(b). The δ(H) values in CX[4] are in consonant with the observed (1)H NMR spectra.     

Calorimetric studies on 2TeO<Subscript>2</Subscript>–V<Subscript>2</Subscript>O<Subscript>5</Subscript> glasses

Glasses of the composition 2TeO₂–V₂O₅ were fabricated via the conventional melt-quenching technique. The amorphous and the glassy nature of the as-quenched samples were confirmed by X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The glass transition and crystallization parameters were evaluated under non-isothermal conditions using DSC. X-ray diffraction studies confirmed the presence of partially oriented crystallites in the heat-treated glasses. Kauzmann temperature (lower bound for the kinetically observed glass transition) was deduced from the heating rate dependent glass transition and crystallization temperatures.     

Experimental evaluation and constitutive modeling of non-proportional deformation for asymmetric steels

Recently non-proportional deformation has received increased attention from researchers working in the area of experimental and computational modeling of metal deformation. However, most of them are numerical in nature with limited experimental data available, making it further difficult to model non-proportional deformation. In the present work, two-stage uniaxial tests, along with uniaxial cyclic and biaxial tests for different stress ratios, have been performed to evaluate deformation behavior of ultra-low carbon high strength automotive steel. Behaviors like cross-effect and hardening stagnation, which are attributed to the evolution of complex dislocation structures, were observed in this steel. It was also noticed that this steel exhibits tension-compression asymmetry. As for constitutive modeling, a modified asymmetric yield function is proposed to be used with a combined isotropic-kinematic hardening model. Also methods to account for the hardening stagnation during reverse loading and the cross-effect during two-stage deformation are proposed. The resulting constitutive model showed reasonably good agreement with experimental results.     

Raman Spectroscopic Analysis of Perovskite-Structured Alkali Metal Fluorides Containing Nickel and Copper Ions

ABSTRACT

The mixed metal fluorides containing alkali metals have a range of important applications in optical and electronic devices. Raman spectrums of two such fluorides were examined. Raman spectrum of KCuF₃ at 300 K exhibited bands at 261, 295, 363, 468, 519, and 549 cm^?1, indicating site symmetry (orthorhombic) lower than the tetragonal symmetry as observed from the powder X-ray diffraction pattern. Cubic KNiF₃ showed bands at 410, 468, and 657 cm^?1. The first two bands were attributed to the second-order phonon scattering, and the band at 657 cm^?1 was assigned to two-magnon peak.     

Electrical transport characteristics of ZnO–Bi2O3–B2O3 glasses

Optically clear glasses in the ZnO–Bi₂O₃–B₂O₃ (ZBBO) system were fabricated via the conventional melt-quenching technique. Dielectric constant and loss measurements carried out on ZBBO glasses unraveled nearly frequency (1 kHz–10 MHz)-independent dielectric characteristics associated with significantly low loss (D?=?0.004). However, weak temperature response was found with temperature coefficient of dielectric constant 18?±?4 ppm °C^?1 in the 35–250 °C temperature range. The conduction and relaxation phenomena were rationalized using universal AC conductivity power law and modulus formalism respectively. The activation energy for relaxation determined using imaginary parts of modulus peaks was 2.54 eV which was close to that of the DC conduction implying the involvement of similar energy barriers in both the processes. Stretched and power exponents were temperature dependent. The relaxation and conduction in these glasses were attributed to the hoping and migration of Bi³⁺ cations in their own and different local environment.     

Zirconyl Chloride Promoted Highly Efficient Domino Synthesis of New 1, 2, 3, 4-Tetrahydroquinoline Derivatives in Water

The tetrahydroquinoline moiety is present in various natural products, and many tetra- hydroquinoline derivatives exhibit a broad range of biological activities1. Therefore, it has attracted continuous interest to develop methods for the synthesis of tetr…     

Graph splicing systems

In this paper, extended graph splicing systems are defined. It is shown that when strings are represented as linear graphs, any recursively enumerable set can be generated by an extended graph splicing system. It is also shown that the computational completeness of extended graph splicing systems can be proved under some constraints too.