All Solid State Nickel(II)‐Selective Potentiometric Sensor Based on an Upper Rim Substituted Calixarene

A new ionophore, i.e. p‐(2‐thiazolazo)calix[4]arene ( I ) has been explored for its selective behavior towards Ni(II) ions. A poly(vinyl chloride) based membrane containing ( I ) as an electroactive material along with sodiumtetraphenylborate (NaTPB), and nitrophenyloctyl ether in the ratio 10 : 100 : 3 : 150 (I:PVC:NaTPB:NPOE) (w/w) was used to fabricate an all solid state nickel(II)‐selective sensor. The developed sensor exhibited a working concentration range of 1.0×10^?6–1.0×10^?1 M, with a Nernstian slope of 28.9±1.0 mV/decade of activity and a response time of 10–15 s. This sensor shows a detection limit of 9.0×10^?7 M. Its potential response remains unaffected of pH in the range 3.0–7.6, and the cell assembly could be used successfully in partially nonaqueous medium (up to 10 % v/v) without any significant change in the slope value or the working concentration range. The sensor worked satisfactorily for about ten weeks and exhibited excellent selectivity over a number of mono‐, bi‐, and tri‐valent cations including alkali, alkaline earth metal, and transition metal ions. It could be used as an indicator electrode for the end point determination in the potentiometric titration of nickel ions against ethylenediaminetetraacetic acid (EDTA) as well as for the determination of nickel ion concentration in real samples.     

Facile and convenient strategy towards synthesis of 4-substituted 2-aminothiazolo[4,5-d]pyridazinones

Convenient synthesis of 4-substituted 2-aminothiazolo[4,5-d]pyridazinones has been achieved in 12 steps with overall yield of 19% by employing Grignard reaction as the key step. The route utilizes well established thiazole ring formation followed by Grignard reaction to introduce substitution at 4-position effectively. In addition to the use of inexpensive chemicals, the present route first time gave access to the 4-substituted 2-aminothiazolo [4,5-d]pyridazinones with free amino group at C-2 position.     

Glycogen synthase kinase-3 inhibition by 3-anilino-4-phenylmaleimides: insights from 3D-QSAR and docking

Glycogen synthase kinase-3, a serine/threonine kinase, has been implicated in a wide variety of pathological conditions such as diabetes, Alzheimer’s disease, stroke, bipolar disorder, malaria and cancer. Herein we report 3D-QSAR analyses using CoMFA and CoMSIA and molecular docking studies on 3-anilino-4-phenylmaleimides as GSK-3α inhibitors, in order to better understand the mechanism of action and structure-activity relationship of these compounds. Comparison of the active site residues of GSK-3α and GSK-3β isoforms shows that all the key amino acids involved in polar interactions with the maleimides for the β isoform are the same in the α isoform, except that Asp133 in the β isoform is replaced by Glu196 in the α isoform. We prepared a homology model for GSK-3α, and showed that the change from Asp to Glu should not affect maleimide binding significantly. Docking studies revealed the binding poses of three subclasses of these ligands, namely anilino, N-methylanilino and indoline derivatives, within the active site of the β isoform, and helped to explain the difference in their inhibitory activity.     

An all-solid-state monohydrogen phosphate sensor based on a macrocyclic ionophore

An all-solid-state electrode, containing a synthesized chiral A₂B₂ macrocyclic compound namely (4R,5R,15R,16R)-4,5,15,16-tetraphenyl-3,6,14,17-tetraazatricyclo [13.3.1.18,12] tetracosa-1(23),8,10,12(24)19,21-hexaene-2,7,13,18-tetrone as an ionophore in polyvinyl chloride (PVC)/polyurethane (PU) membrane matrix, has been developed for the selective quantification of monohydrogen phosphate ions. The best performing membrane contained PVC, PU, ionophore, and nitrophenyl octyl ether as a plasticizer in the ratio 32.2:2.6:65.1 (w/w, %). It exhibited a near-Nernstian slope of 31.0 ± 1.0 mV/decade of activity for HPO₄²⁻ ions in the concentration range of 1.0 × 10⁻⁶ to 1.0 × 10⁻² M at pH 7.4. The detection limit of the electrode was 8.4 × 10⁻⁷ M and the life time was six weeks. The electrode displayed excellent selectivity for monohydrogen phosphate over other anions and the selectivity sequence was determined as HPO₄²⁻ > SO₄²⁻ > Ac⁻ > NO₃⁻ > ClO₄⁻ > Cl⁻ > I⁻. The selective electrode for the monohydrogen phosphate ions was evaluated with a standard reference material (SRM 1548) and the titration of the sample solution.     

Multiwalled carbon nanotubes as efficient adsorbent for solid-phase extraction of chemical warfare agents and related chemicals from water

Optimization of extraction and enrichment parameters of chemical warfare agents and their related chemicals from water are presented using multiwalled carbon nanotubes (MWCNTs) as solid-phase extractant. Selected analytes were O,O'-dialkyl alkylphosphonates, nerve agent and mustards. Extraction parameters, including sample volume, nature and volume of washing and eluting solvent, were optimized. Recoveries of analytes were determined by GC-MS and ranged from 81 to 104%. A comparison with C(18), hydrophilic-lipophilic balance and active carbon sorbents demonstrated the superiority of MWCNTs for non-toxic analogues of nerve agents. Optimized conditions involve 40?mg MWCNTs as the sorbent, 5.0?mL water as the washing solvent, 3?mL ethyl acetate as the eluent and sample loading of 10?mL water spiked at 0.1?μg/mL. The limits of detection (LOD) were achieved down to 1 and 0.05?ng/mL in full scan and selected ion-monitoring modes, respectively.     

Synthesis,characterization and microbiocidal studies of novel ionic liquid tagged Schiff bases

The synthesis of novel imidazolium ionic liquid, tagged Schiff, has been described. The synthesis was achieved in three steps from 2,4-dihydroxybenzaldehyde by selective alkylation with 1,3-dibromopropane, followed by reaction with 1-methylimidazole and Schiff base formation with aromatic amines. The compounds were evaluated for antibacterial and antifungal activities. The ionic liquid tagged Schiff base 4a showed the inhibition of both Gram positive and Gram negative bacteria. It also showed broad spectrum antifungal activity against all four tested fungi; however, 4f showed highest antifungal activity against A. niger.     

Welding of polymers using a 2 μm thulium fiber laser

Absorber-free transmission and butt-welding of different polymers were performed using thulium fiber laser radiation at the wavelength 2 μm. The relations between the laser process conditions and the dimensions and quality of the seam were investigated by means of optical and phase-contrast microscopy. Mechanical properties of the weld joints were studied in tensile strength tests. Laser-welded polyethylene samples revealed a tensile strength of greater than 80% of the bulk material strength. Transmission welding of different polymer combinations featured the formation of different joint classes depending on the spectral properties. The experiments demonstrate new application areas of mid-IR fiber laser sources for materials processing.     

A Two-Dimensional Kinetic Triangulation with Near-Quadratic Topological Changes

A triangulation of a set S of points in the plane is a subdivision of the convex hull of S into triangles whose vertices are points of S. Given a set S of n points in each moving independently, we wish to maintain a triangulation of S. The triangulation needs to be updated periodically as the points in S move, so the goal is to maintain a triangulation with a small number of topological events, each being the insertion or deletion of an edge. We propose a kinetic data structure (KDS) that processes topological events with high probability if the trajectories of input points are algebraic curves of fixed degree. Each topological event can be processed in time. This is the first known KDS for maintaining a triangulation that processes a near-quadratic number of topological events, and almost matches the lower bound [1]. The number of topological events can be reduced to if only k of the points are moving.     

Gas chromatography/mass spectrometric analysis of N,N-dialkylaminoethyl-2-chlorides and trimethylsilyl derivatives of N,N-dialkylaminoethan-2-ols for verification of the Chemical Weapons Convention

Gas chromatography/electron ionization mass spectrometry (GC/EI-MS) of N,N-dialkylaminoethyl-2-chlorides (DAAECls) and trimethylsilyl (TMS) derivatives of N,N-dialkylaminoethan-2-ols (DAAEAs) has been carried out. GC/EI-MS data of these compounds are of importance for verification of the Chemical Weapons Convention (CWC). Based on these EI mass spectra, generalized fragmentation routes are proposed that rationalize most of the characteristic ions.     

Studies of new indole alkaloid coupling methods for the synthesis of haplophytine

[reaction: see text] The two novel bisindole alkaloid structures shown can be synthesized in a few steps from the canthiphytine derivative 9.