Syntheses of 5‐alkylthio‐1,3‐diaryl‐1,2,4‐triazoles

Arylation of the readily available 3‐alkythio‐5‐aryl‐1,2,4‐triazoles gave 5‐alkylthio‐1,3‐diaryl‐1,2,4‐triazoles in moderate yield. The structures of the latter were confirmed by NOE and ¹³C‐NMR.     

Catalyst-free,aqueous and highly diastereoselective synthesis of new 5-substituted 1H-tetrazoles via a multi-component domino Knoevenagel condensation/1,3 dipolar cycloaddition reaction

An approach for the synthesis of new 5-substituted-tetrazoles via multi-component domino Knoevenagel condensation/1,3 dipolar cycloaddition reaction of carbonyl compounds, malononitrile and sodium azide in water without assistance of any catalyst has been reported. This general protocol provides a wide variety of 5-substituted 1H-tetrazoles in good yields under mild reaction conditions.     

Interaction of glucose oxidase with alkyl-substituted sepharose 4B

Glucose oxidase (GOD) is often used in immobilized forms for determination of glucose. To examine the possibility of its adsorption by hydrophobic interactions, palmityl-substituted Sepharose 4B (Sepharoselipid) was employed as an adsorptive matrix. Various conditions were used in tests to improve the limited immobilization of the enzyme observed under normal (native) conditions, including use of high concentrations of denaturing agents. Of the denaturants used, only the cationic detergent dodecyl trimethyl ammonium bromide was effective in denaturing the protein and exposing its hydrophobic sites for interaction with alkyl residues on the support. This, followed by the process of renaturation, provided catalytically active immobilized preparations. The apoenzyme, prepared by treatment of the holoenzyme with acidified (NH4)2SO4 or thermal denaturation, was totally immobilized on the support. Furthermore, it was shown that either flavin adenine dinucleotide (FAD) or the alkyl residues, not both, may interact with the nucleotide site at any given time. Results are discussed in terms of high rigidity of GOD molecule and limited exposure of hydrophobic sites in its native structure. The observations are in accord with suggestions in the literature that the FAD pocket is a very narrow channel of hydrophobic properties, adapted to accept its natural coenzyme.     

New Polydentate Trimethylsilyl Chalcogenide Reagents for the Assembly of Polyferrocenyl Architectures

A series of polychalcogenotrimethylsilane complexes Ar(CH₂ESiMe₃)_n, (Ar=aryl; E=S, Se; n=2, 3, and 4) can be prepared from the corresponding polyorganobromide and M[ESiMe₃] (M=Na, Li). These represent the first examples of the incorporation of such a large number of reactive ?ESiMe₃ moieties onto an organic molecular framework. They are shown to be convenient reagents for the preparation of the polyferrocenylseleno‐ and thioesters from ferrocenoyl chloride. The synthesis, structures, and spectroscopic properties of the new silyl chalcogen complexes 1,4‐(Me₃SiECH₂)₂(C₆Me₄) (E=S, 1 ; E=Se, 2 ), 1,3,5‐(Me₃SiECH₂)₃(C₆Me₃) (E=S, 3 ; E=Se, 4 ) and 1,2,4,5‐(Me₃SiECH₂)₄(C₆H₂) (E=S, 5 ; E=Se, 6 ) and the polyferrocenyl chalcogenoesters [1,4‐{FcC(O)ECH₂}₂(C₆Me₄)] (E=S, 7 ; E=Se, 8 ), [1,3,5‐{FcC(O)ECH₂}₃(C₆Me₃)] (E=S, 9 ; E=Se, 10 ) and [1,2,4,5‐{FcC(O)ECH₂}₄(C₆H₂)] (E=S, 11 illustrated; E=Se, 12 ) are reported. The new polysilylated reagents and polyferrocenyl chalcogenoesters have been characterized by multinuclear NMR spectroscopy (¹H, ¹³C, ⁷⁷Se), electrospray ionization mass spectrometry and, for complexes 1 , 2 , 3 , 4 , 7 , 8 , and 11 , single‐crystal X‐ray diffraction. The cyclic voltammograms of complexes 7 – 11 are presented.     

Hydroxyapatite Wrapped Multiwalled Carbon Nanotubes/Ionic Liquid Composite Electrode: A High Performance Sensor for Trace Determination of Lead Ions

A nanocomposite consisting of multiwalled carbon nanotubes wrapped with hydroxyapatite (HA/MWCNTs) was used in the construction of a new composite paste electrode using an ionic liquid as the binder. The stable surface in aqueous solutions as well as the high sorptive behaviors towards heavy metal ions and the favorable charge transfer make the electrode highly efficient especially for stripping or adsorptive analysis. The analysis of Pb²⁺ as a model of heavy metal ions has been performed. Good sensitivity, detection limit, selectivity and reproducibility were obtained for the suggested sensor. The linear range of the electrode response covered four orders of magnitude (1 nM–10 µM), in two linear ranges. The obtained detection limit for Pb²⁺ was 2×10^?11 M.     

Synthetic Approaches towards the Sulfonamide Substituted‐1,5‐Diarylimidazole‐2‐thiones as Selective Cyclooxygense‐2 inhibitors

A new series of sulfonamide substituted 1,5‐diarylimidazole, possessing C‐2 alkylthio moiety, were synthesized for their cyclooxygense‐2 (COX‐2) inhibitory activity starting from condensation of N,N‐dibenzylaminosulfonylphenacylamine hydrochloride ( 2 ) and corresponding isothiocyanate in the presence of Et₃N, followed by alkylation in the basic medium. In concomitant with these intermediates, 2‐arylamino‐5‐arylthiazole derivatives 5 were also produced. The ratio of these two products was variable with different isothiocyanates. Final debenzylation was achieved using concentrated sulfuric acid to give the title sulfonamides 8 .     

Synthesis,crystal structure,and electrochemical properties of Ni(II) and Cu(II) complexes with two unsymmetrical N2O2 Schiff base ligands

Nickel(II) and copper(II) complexes of two unsymmetrical tetradentate Schiff base ligands [Ni(Me-salabza)] (1), [Cu(Me-salabza)] (2) and [Ni(salabza)] (3), {H₂salabza = N,N′-bis[(salicylidene)-2-aminobenzylamine] and H₂Me-salabza = N,N′-bis[(methylsalicylidene)-2-aminobenzylamine]}, have been synthesized and characterized by elemental analysis and spectroscopic methods. The crystal structures of 2 and 3 complexes have been determined by single crystal X-ray diffraction. Both copper(II) and nickel(II) ions adopt a distorted square planar geometry in [Cu(Me-salabza)] and [Ni(salabza)] complexes. The cyclic voltammetric studies of these complexes in dichloromethane indicate the electronic effects of the methyl groups on redox potential.     

One-pot and novel route for the synthesis of 4-substituted-l,2,4- triazolidine-3,5-diones

The efficient and one-pot synthesis of 4-substituted-1,2,4-triazolidin-3,5-dione derivatives(4-substituted urazoles) via combination of triphosgene, substituted anilines, and ethyl carbazate in the presence of cesium carbonate is presented.     

Synthesis and Characterization of H3PW12O40 and H3PMo12O40 Nanoparticles by a Simple Method

In this study H₃PW₁₂O₄₀·9H₂O and H₃PMo₁₂O₄₀·6H₂O (HPA) particles were changed into nano forms by heat-treatment in an autoclave as a simple, repaid, inexpensive and one step method. The particle size of these nanoparticles was around 25 nm. The as-synthesized nanostructures were characterized by dynamic light scattering, X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and inductively coupled plasma analyzer. Thermal stability of nanoparticles was surveyed by thermal gravimeter analyse. Acidity of prepared nanoparticles was investigated by pyridine adsorption method. Results showed rising acidity by declining particle size of HPA.