Nanodiamond Decorated with Silver Nanoparticles as a Sensitive Film Modifier in a Jeweled Electrochemical Sensor: Application to Voltammetric Determination of Thioridazine

Nanodiamond? graphite (NDG) decorated with Ag nanoparticles (AgNPs‐NDG) was prepared and used to construct a novel sensitive sensor for the voltammetric determination of thioridazine (TR). The results indicate a remarkable increase in the oxidation peak currents together with a negative shift in the oxidation peak potentials, in comparison to the bare pyrolytic graphite electrode. Remarkable enhancement in microscopic area of the electrode along with strong adsorption of TR on the surface of the modified electrode resulted in a considerable increase in the peak current of TR. The surface morphology and the nature of the composite film deposited on PGE were characterized by scanning electron microscopy, atomic force microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Experimental variables, such as the deposited amount of the modifier suspension, pH of the supporting electrolyte, the accumulation potential and time are optimized by monitoring the CV responses of TR. Under the optimal conditions, the modified electrode showed a wide linear response to the concentration of TR in the range of 0.08–100 µM with a detection limit of 0.01 µM. The prepared modified electrode showed several advantages: simple preparation method, high stability and uniformity in the composite film, high sensitivity, long‐term stability and remarkable voltammetric reproducibility in response to TR. The modified electrode can be successfully applied for accurate determination of trace amounts of TR in pharmaceutical and clinical preparations.     

Experimental investigation of cluster properties in dense gas-solid fluidized beds of different diameters

The local solid flow structure of a bubbling fluidized bed of sand particles was investigated m three different columns to characterize the properties of clusters. The experiments were performed using a reflective optical fiber probe. The variations in size, velocity, and void fraction of the clusters due to changes in the superficial gas velocity, particle size, and radial positions were studied. The results indicate that the velocity of the clusters remained unchanged while their size increased as the column diameter increased. In addition, the radial profile of the clusters＇ velocity did not depend on the radial position. The results indicate that larger particles form larger clusters, which move slower.     

One-Pot Synthesis of Novel 2-(Thiazol-2-yl)-4,5-dihydropyridazin-3(2H)-one Derivatives Catalyzed by Activated KSF

A series of 2-(thiazol-2-yl)-4,5-dihydropyridazin-3(2H)-one derivatives were synthesized by one-pot multicomponent cyclocondensation of ketoacid, thiosemicarbazide, and phenacyl bromide using catalytical amount of KSF in EtOH under reflux. The straightforward synthesis, presence of two important class of heterocyclic rings in the individual molecule, easy workup of the products, rapid reaction, mild conditions, and good to excellent yields are notable features of this protocol.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Synthesis,characterization, and applications of novel Co(II)-pyridoxal phosphate-Schiff base/SBA-15 as a nanocatalyst for the green synthesis of benzothiazole heterocycles

Mesoporous heterogeneous santa barbara amorphous (SBA)-15-supported cobalt complex, as a novel nanocatalyst containing N–O chelating Schiff-base ligand was successfully synthesized by the reaction of SBA-15 and Cobalt(II)-Schiff-base complex. The Co(II)-Schiff base complex also was prepared for the first time, by the reaction of pyridoxal 5′-phosphate or PLP (biological active form of vitamin B6), 3-(aminopropyl)-triethoxysilane in methanol that complexation with CoCl₂. The subsequent grafting of entitled complex to SBA-15 afforded Co(II)-PLP-Schiff base/SBA-15 mesoporous catalyst. Characterization of the product was carried out with powder X-ray diffraction, Brunauer–Emmett–Teller nitrogen adsorption–desorption, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, atomic absorption spectroscopy, and inductively coupled plasma, Fourier-transform infrared spectroscopy. The results revealed the retention of the textural properties and hexagonally uniform structures of SBA-15 during the grafting procedure. This nanocatalyst was applied successfully for one-pot synthesis of various benzothiazole heterocycles under green conditions. This catalyst is an active, reusable, and stable nanomaterial with no leaching of metal ions to the reaction medium. It was used for the synthesis of desired benzothiazole heterocycles by the cyclo-condensation of aryl-aldehydes with 2-aminothiophenol with good to excellent yields and under green conditions.     

Synthesis of Cyano‐pyrrolo[1,2‐a][1,10]phenanthroline Derivatives Using a Multicomponent Condensation

1,10‐Phenanthroline reacts with malonitrile and aldehydes in the presence of isocyanides as domino‐Knoevenagel‐nucleophilic cycloaddition for generation of a new class of 10‐(aryl)‐11‐(alkyl‐ or arylamino‐)pyrrolo[1,2‐a][1,10]phenanthroline‐9‐carbonitrile compounds in excellent yield. All compounds are fully characterized with one structurally authenticated by a single X‐ray diffraction study.     

Kinetic and Mechanistic Insights into the Pathway Leading to Cyclic Crystalline Phosphorus Ylide Formation in the Presence of 3‐Chloropentane‐2,4‐dione: Theoretical and Stopped‐Flow Approaches

In this work, three speculative mechanisms of the reaction between triphenylphosphine and dimethyl acetylendicarboxylate in the presence of 3‐chloropentane‐2,4‐dione were energetically and thermodynamically developed using quantum mechanical calculations and were profoundly compared with stopped‐flow and UV spectrophotometry approaches. The third speculative mechanism that led to the five‐membered ring structure was experimentally and theoretically favorable. The five‐membered ring structure of product was characterized by X‐ray crystallographic data. Also, steps 1 and 2 of the third mechanism were determined as fast and rate‐determining steps, respectively. The experimental kinetic evidence of the formation and decay of intermediate in steps 1 and 2 (fast and rate‐determining steps, respectively) was compatible with theoretical data. Experimental kinetic data were recognized for overall reaction along with activation parameters for fast and rate‐determining steps of the reaction. Theoretical kinetic data (k and E_a) and activation parameters (ΔG^≠, ΔS,^≠ and ΔH^≠) were calculated for each step and overall reactions.     

A new approach to phospholipid synthesis using tetrahydropyranyl glycerol: rapid access to phosphatidic acid and phosphatidylcholine, including mixed-chain glycerophospholipid derivatives

A new synthesis of phosphatidic acid and phosphatidylcholine is reported, relying on the preparation of 3-tetrahydropyranyl-sn-glycerol as the key intermediate for sequential introduction of the primary and secondary acyl functions to produce chiral diglycerides that are phosphorylated to obtain the target phospholipid compounds.     

A Monte Carlo simulation of image misalignment effects in diffusion tensor imaging

Diffusion tensor imaging (DTI) and tractography are noninvasive MRI methods, providing an insight on microscopic structural information of anisotropic tissues in vivo. The success of this technique stems on a watchful choice of imaging parameters and post-acquisition reconstruction. In the present work, we have focused on the problem of residual linear image misalignment in the DTI data and its effects on the parameters of the diffusion tensor and fiber tracking in human brain. We demonstrate substantial sensitivity of the reconstructed diffusion tensor and fiber tractography on increasing amplitude of artificially induced random image misalignment in the DTI. We show that already a submillimeter image misalignment in the DTI is an important source of error, which may potentially mask pathological presentations of the diseases and may partially explain variations in the results obtained from the DTI. Finally, we evaluated four implementations of image registrations and demonstrate their variable performance. This further supports the fact that a robust image registration must be performed to ensure reliable and reproducible diffusion tensor mapping and reconstruction of white matter (WM) fibers.