Synthesis of a palladium(II) complex of a <Emphasis Type="Italic">N</Emphasis>-heterocylic carbene via transmetalation: crystal structure and antibacterial studies

An Ag(I)-N-heterocylic carbene (NHC) complex, [Ag(L)₂]PF₆ (L = 1-(2′-methylbenzyl)-3-(2″-propyl)benzimidazolium), was used as a transfer agent for the synthesis of a Pd(II)–NHC complex, formulated as [PdCl(L)₂(MeCN)]PF₆ (Pd1). The complex Pd1 was characterized by ¹H and ¹³C NMR, FTIR spectroscopy and elemental analysis. Single crystal X-ray diffraction analysis reveals that the Pd(II) atom has a square planar geometry. This complex was screened for its antibacterial potential against the Gram-negative bacteria Escherichia coli (ATCC 25922) and the Gram-positive bacteria Staphylococcus aureus (ATCC 12600). These results are compared with those obtained for a standard antibiotic, ampicillin, and also the corresponding Ag(I)–NHC complex.     

Surface properties of semiconductor analogs of CdB<Superscript>VI</Superscript> and their solid substitution solutions

The physicochemical (acidic-basic, adsorption, and electrophysical) surface properties of binary semiconductor analogs of CdB^VI (CdTe, CdSe, and CdS), and (CdTe)_x(CdSe)_1–x, and (CdTe)_x(CdS)_1–x solid substitution solutions were studied using modern methods and equipment. The nature of the active centers and the mechanisms of acidic-basic, adsorption (involving СО), and electronic interactions, interrelated tendencies in variation of the surface properties under study, and their correlations with the known bulk physicochemical properties were elucidated; the property–composition diagrams were constructed, which were used to reveal the most active adsorbents suggested for use as materials for СО (carbon monoxide) microimpurity sensors.     

Nickel(II) complexes bearing pyrazolylpyridines: synthesis,structures and ethylene oligomerization reactions

Reactions of 2‐bromo‐6‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridine ( L1 ) and 2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridine ( L2 ) with NiCl₂ and NiBr₂ led to the formation of their respective metal complexes [NiCl₂(L1)] ( 1 ), [NiBr₂(L1)] ( 2 ) and [NiBr₂(L2)] ( 3 ) in moderate to high yields. The complexes were characterized using elemental analyses, mass spectrometry and single‐crystal X‐ray diffraction for 2 . The solid‐state structure of 2 confirmed the bidentate coordination mode of L1 and formation of a monometallic compound. Activation of the nickel(II) pre‐catalysts with methylaluminoxane afforded active catalysts in the ethylene oligomerization reaction to produce mainly butenes (84–86%). In contrast, activation of nickel(II) pre‐catalyst 2 with ethylaluminium dichloride resulted in partial Friedel–Crafts alkylation of the toluene solvent by the preformed oligomers. Complex structure, nature of co‐catalyst employed, type of solvent and reaction conditions influenced the catalytic behaviour of these pre‐catalysts. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis of steroidal thiadiazoles from steroidal ketones

Syntheses of steroidal heterocycles containing a five-membered N,S- heterocycle attached at the 6,7 positions of the B ring are reported. 5Alpha-cholestane-6-one (1), its 3beta-acetoxy- (2) and 3beta-chloro- (3) analogues reacted with semicarbazide and aqueous sodium acetate in refluxing ethanol to yield 5alpha-cholestan-6-one-semicarbazone 1a and its 3-beta-acetoxy and 3beta-chloro derivatives 2a and 3a, respectively. The reactions of 1a, 2a and 3a with thionyl chloride in dichloromethane at low temperature afforded the cyclized thiadiazole 4 and its 3beta-acetoxy- and 3beta-chloro analogues 5 and 6 in good yields.     

Investigation on the Use of Graphene Oxide as Novel Surfactant for Stabilizing Carbon Based Materials

The present work reported on the use of graphene oxide (GO) as effective dispersant to isolate different carbon allotropes. The nature of its chemical structure which consists of hydrophobic and hydrophilic components enables GO to behave as surfactant, paving routes for dissolution of graphitic materials and achieving surfactant free all-carbon solutions. Two additional carboneous materials under the family of fullerene (carbon nanofiber—CNF) and graphite (graphene nanoplatelets—GnP) were introduced within the present study to form a new GO based hybrid complexes on top of the commonly investigated carbon nanotube (CNT) based GO hybrid. Investigation on GO stability with respect to particle size and zeta potential measurements showed that the strength of its dispersibility was highly dependent on its morphological size and less affected by the pH. Rheological study revealed that GO shear–strain relationship is highly sensitive to the particle size. The GO viscosity experienced dramatic changes from Newtonian toward shear thinning behaviors as the particle size increases. Thermal conductivity measurement highlighted as high as 8% increase in magnitude with the addition of CNT, CNF, and GnP carbon constituents, indicating that the enhancement may be attributed to the much efficient thermal transport along the conducting path of pristine carbon allotropes.     

Synthesis,characterization, and electroanalytical studies of Pb2+-selective polypyrrole-Zr(IV) phosphate ion exchange membrane

Journal of Solid State Electrochemistry - Polypyrrole-Zr(IV) phosphate (PPyZP) composite cation exchange material was synthesized by chemical oxidative polymerization of pyrrole with the help of...     

A new flavone from Malaysia Borneo Marsdenia tinctoria

Marsdenia tinctoria is an indigo producing plant commonly found in Borneo, Malaysia. In this present study, one new flavone kapitone (1) and three known compounds, that is 3,2’-dihydroxyflavone (2), 1-methylcyclobutene (3) and dimethyl isatoate (4) were isolated from the Malaysia Borneo M. tinctoria R. Br. (Apocynaceae). These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods.