The thermal decomposition of bis(N,N-diallyldithiocarbamato)Cd(II) in a “one-pot” synthesis in tri-n-octylphosphine oxide (TOPO) and hexadecylamine (HDA) afforded CdS (TOPO-CdS and HDA-CdS) of varying optical properties and morphologies. The influence of the ratio of the precursor concentration to the capping molecule, as a factor affecting the morphology and size of the nanoparticles, was investigated. The particles varied in shape from spheres to rods and show quantum size effects in their optical spectra with clear differences in the photoluminescence (PL) spectra. The PL spectrum of the HDA capped CdS nanoparticles has an emission maximum centred at 468, 472, and 484 nm for the precursor to HDA concentration ratio of 1 : 10, 1 : 15, and 1 : 20, respectively, while the TOPO capped nanoparticles show emission peaks at 483, 494, and 498 nm at the same concentration ratio. Powdered X-ray diffraction (p-XRD) shows the nanoparticles to be hexagonal. The crystallinity of the nanoparticles was evident from high resolution transmission electron microscopy (HRTEM) which gave well-defined images of particles with clear lattice fringes.
In order to characterize the sorption kinetics of phenobarbital sodium and amobarbital sodium on natural Na � montmorillonite, the influence of the initial drug concentration and clay particles sizes was investigated. Equilibrium isotherms have been measured and analyzed using a Langmuir isotherm model. The affinity of drugs sorbed onto clay varied in the following descending order: phenobarbital sodium ] amobarbital sodium, respectively 11.2 and 9.1 mg/g. Also, sorption of phenobarbital sodium and amobarbital sodium on Na-montmorillonite was studied as a function of pH. The results show that adsorption of the drugs is highest below the pHZPC due the neutrality of the drugs which adsorbs via an attraction of the positively charged surface sites at lower pH by weak van der Waals forces.
This paper is dedicated to Professor Pierre Dixneuf for his outstanding contributions to organometallic chemistry and homogeneous catalysis, especially with ruthenium-arene complexes.Twelve imidazolium-, imidazolinium-, or benzimidazolium-2dithiocarboxylate zwitterions with aliphatic or aromatic substituents on their nitrogen atoms, including four new unsymmetrical 1-alkyl-3-arylimidazolium derivatives, were obtained in high yields (62-96 %) upon reaction of azolium salts with CS 2 and Cs 2 CO 3 in acetonitrile at room temperature. Compared to the previous strategies devised for the synthesis of NHC•CS 2 betaines, this novel procedure relied on an innocuous, weak base and could be applied under mild aerobic conditions. All the new compounds were fully characterized by various analytical techniques and the molecular structures of two of them were determined by XRD analysis. An associative mechanism involving the concerted reaction of the azolium salts with both CS 2 and CO 3 2À was tentatively proposed to account for the formation of the zwitterionic adducts without the intervention of free carbenes. This would explain the good results obtained with a weak inorganic base that lacks the strength needed to deprotonate the azolium salt substrates.
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