Intercalated Poly (2-acrylamido-2-methyl-1-propanesulfonic Acid) into Sulfonated Poly (1,4-phenylene ether-ether-sulfone) Based Proton Exchange Membrane: Improved Ionic Conductivity

A series of hybrid proton exchange membranes were synthesized via in situ polymerization of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) PMPS with sulfonated poly (1,4-phenylene ether-ether-sulfone) (SPEES). The insertion of poly (2-acrylamido-2-methyl-1-propanesulfonic acid) PMPS, between the rigid skeleton of SPEES plays a reinforcing role to enhance the ionic conductivity. The synthesized polymer was chemically characterized by fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance ¹H NMR spectroscopy to demonstrate the successful grafting of PMPS with the pendent polymer chain of SPEES. A variety of physicochemical properties were also investigated such as ion exchange capacity (IEC), proton conductivity, water uptake and swelling ratio to characterize the suitability of the formed polymer for various electrochemical applications. SP-PMPS-03, having the highest concentration of all PMPS, shows excellent proton conductivity of 0.089 S cm⁻¹ at 80 °C which is much higher than SPEES which is ~0.049 S cm⁻¹. Optimum water uptake and swelling ratio with high conductivity is mainly attributed to a less ordered arrangement polymer chain with high density of the functional group to facilitate ionic transport. The residual weight was 93.35, 92.44 and 89.56%, for SP-PMPS-01, 02 and 03, respectively, in tests with Fenton’s reagent after 24 h. In support of all above properties a good chemical and thermal stability was also achieved by SP-PMPS-03, owing to the durability for electrochemical application.     

Skeletal diverse synthesis of N-fused polycyclic heterocycles via the sequence of Ugi-type MCR and CuI-catalyzed coupling/tandem Pictet-Spengler reaction

Several diversity-oriented syntheses of N-fused polycyclic heterocycles have been demonstrated but most of them are based on point diversity within the same library and usually involve time-consuming sequential multistep syntheses, which also suffer from low yields and/or poor precursor scopes. We have developed a new strategy for the syntheses of skeletal diverse N-fused polycyclic compounds via an Ugi-type MCR followed by a CuI-catalyzed coupling reaction or tandem Pictet-Spengler reaction. This two-step sequence provides eight distinct skeleton of fused {6-5-5-6}, {5-5-5-6}, {6-5-6-6}, and {5-5-6-6} ring systems that have applications in medicinal chemistry and chemical genetics too.     

3-Glycidoxypropyltrimethoxysilane mediated in situ synthesis of noble metal nanoparticles: application to hydrogen peroxide sensing

The in situ synthesis is reported of noble metal nanoparticles via 3-glycidoxypropyltrimethoxysilane mediated reduction of 3-aminopropyltrimethoxysilane treated metal salts during sol-gel processing. The method described involves the synthesis of uniform spherical nanoparticles of gold, silver and palladium with controlled size that can be directly utilized for thin film preparation. A detailed study of the synthesis and application of gold nanoparticles to the electrochemical detection of hydrogen peroxide was carried out and reveals that the amplification of hydrogen peroxide sensing is size-dependent. In addition, these nanoparticles exhibit excellent compatibility towards composite preparation. As an example, a nanocomposite with Prussian Blue (PB) is synthesized and found to be useful for the fabrication of chemically modified electrodes (CME). The resulting CME shows dramatic improvement in the electrochemistry of PB with gradual enhancement in electrocatalytic efficiency towards hydrogen peroxide sensing. The nanocomposite is used to study the direct and horseradish peroxidase (HRP)-catalyzed reduction of hydrogen peroxide. The results recorded for hydrogen peroxide analysis show an improvement in sensitivity and limit of detection on decreasing the size of gold nanoparticles in all cases.     

Coordination polymers of Mn2+ and Dy3+ ions built with a bent tricarboxylate: metamagnetic and weak anti-ferromagnetic behavior

Two new coordination polymers have been synthesized with Mn(2+) and Dy(3+) ions using a new bent ether-bridged tricarboxylic acid ligand, o-cpiaH(3) (5-(2-carboxy-phenoxy)-isophthalic acid). The ligand readily reacts with a Mn(2+) salt in presence of pyridine (py) under hydrothermal condition to afford a 3D coordination polymer {[Mn(9)(o-cpia)(6)(py)(3)(3H(2)O)]·H(2)O}(n) (1), that contains two types of polymeric chains. One of them is merely carboxylate bridged Mn(2+) where each metal ion shows both penta- and hexa-coordination. The other chain consists of carboxylate-bridging along with terminally bound pyridines providing both penta- and hexa-coordination to each metal ion. When o-cpiaH(3) is treated with Dy(NO(3))(3).xH(2)O under solvothermal condition, it gives rise to an unusual double layer (6,6) connected 2D coordination polymer {[Dy(o-cpia)]}(n)(2), where each metal ion is hexacoordinated. The double layer 2D sheets are stacked to each other in AA··· fashion through strong C-H···π interactions to generate an overall 3D supramolecular architecture. Both the complexes have been characterized by single crystal X-ray diffraction, IR spectroscopy, thermogravimetry and elemental analysis. Variable temperature magnetic susceptibility measurements indicate that 1 exhibits metamagnetic behavior while 2 shows weak antiferromagnetic behavior.     

Synthesis,characterization, and in vitro antimicrobial and antitumor activities of some tetraphenylstibonium(V) carboxylates

Several hitherto unreported pentacoordinated tetraphenylstibonium(V) carboxylates of general formula (C₆H₅)₄SbL, where L = o‐OHC₆H₅COO , (C₆H₅)₂C(OH)COO , 2‐(6‐OCH₃C₁₀H₆)CH(CH₃)COO , ArCH(OH)COO (Ar = C₆H₅, p‐CF₃C₆H₄, and p OCH₃C₆H₄), have been prepared and characterized by elemental analysis, solid state IR, ¹H NMR, and ¹³C NMR spectra, conductivity, and molecular weight measurements. Spectroscopic data together with solution phase studies conform to the requirement of triagonal‐bipyramidal configuration for these compounds. They were tested for in vitro antifungal (against Aspergillus flavus and Aspergillus niger) and antibacterial (against Staphylococcus aureus and Klebsiella pneumoniae) activities. The in vitro antitumor activity of all stibonium carboxylates was examined against MCF‐7 cell line. A few of them were found to exhibit moderate to significant biological activity. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:688–693, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20498     

Spatial symmetry and conservation of orbital angular momentum in spontaneous parametric down-conversion

Directly contradictory arguments coexist regarding the conservation rule of orbital angular momentum in spontaneous parametric down-conversion. We analytically show how this rule is decided by spatial symmetry. We discover that the down-converted photon pairs can carry non-negligible extrinsic orbital angular momentum in the degrees of relative-movement freedom due to spatial symmetry breaking, leading to nonconservation of total orbital angular momentum in type-II down-conversion. Also, we demonstrate that the traditional technique does not measure the extrinsic orbital angular momentum.     

Searching Anti-Zika Virus Activity in 1H-1,2,3-Triazole Based Compounds

Zika virus (ZIKV) is a mosquito-borne virus belonging to the Flaviviridae family and is responsible for an exanthematous disease and severe neurological manifestations, such as microcephaly and Guillain-Barré syndrome. ZIKV has a single strand positive-sense RNA genome that is translated into structural and non-structural (NS) proteins. Although it has become endemic in most parts of the tropical world, Zika still does not have a specific treatment. Thus, in this work we evaluate the cytotoxicity and antiviral activities of 14 hybrid compounds formed by 1H-1,2,3-triazole, naphthoquinone and phthalimide groups. Most compounds showed low cytotoxicity to epithelial cells, specially the 3b compound. After screening with all compounds, 4b was the most active against ZIKV in the post-infection test, obtaining a 50% inhibition concentration (IC₅₀) of 146.0 µM and SI of 2.3. There were no significant results for the pre-treatment test. According to the molecular docking compound, 4b was suggested with significant binding affinity for the NS5 RdRp protein target, which was further corroborated by molecular dynamic simulation studies.     

A stochastic probing algorithm for global optimization

Recently, simulated annealing methods have proven to be a valuable tool for global optimization. We propose a new stochastic method for locating the global optimum of a function. The proposed method begins with the subjective specification of a probing distribution. The objective function is evaluated at a few points sampled from this distribution, which is then updated using the collected information. The updating mechanism is based on the entropy of a move selecting distribution and is loosely connected to some notions in statistical thermodynamics. Examples of the use of the proposed method are presented. These indicate its superior performance as compared with simulated annealing. Preliminary considerations in applying the method to discrete problems are discussed.     

Necessary conditions for the convergence of Lebesgue-Fourier series

In this paper, necessary conditions have been investigated for the convergence of Fourier series at a point. An attempt has also been made to obtain a necessary and sufficient condition for the convergence of Fourier series of a function in a certain subspace ofL.