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Given the importance of fluorinated drugs and agrochemicals, fluoroalkylation of organic electrophiles that can be performed at a late stage of chemical synthesis has attracted a flurry of contributions. New fluoroalkyl groups can be obtained by insertion of fluoroalkenes into Cu--H bonds. Chlorotrifluoroethylene undergoes regioselective insertion in its reaction with Stryker's reagent, [[CuH([PPh.sub.3])].sub.6] and triphos to give [[Cu(CFClC[F.sub.2]H)([micro]-[[kappa].sup.1], [[kappa].sup.1]-triphos)].sub.2], which mediates the fluoroalkylation of several aroyl chlorides (triphos = bis(2-diphenylphosphinoethyl)-phenylphosphine). In contrast, attempted--[R.sup.F] transfer to aryl iodides instead affords aryl-aryl coupling products. Key words: copper fluoroalkyl, fluoroalkylation, chlorotrifluoroethylene, triphos, Introduction The development of new methodologies for perfluoroalkylation of organic electrophiles has been explored extensively by scientists over the last decade due to the widespread application of fluorine in pharmaceuticals, [...]

This work describes a new method for the preparation of copper N-heterocyclic carbene (NHC) complexes, which is conducted under air with mild conditions, using bench-stable precursors and a weak base ([NEt.sub.3]). Under optimized conditions, the complexes were prepared in short reaction times of 1 h, giving moderate to good yields after purification by column chromatography. Commonly utilized NHC-HCl salts were found to be applicable reacting with CuCl or CuI giving [(NHC)CuX]-type complexes (X = Cl, I). This study adds to the growing literature in the preparation of catalytically relevant transition metal NHC complexes under mild and operationally simple conditions. Key words: carbenes, NHCs, copper, preparation, catalysis, Introduction N-Heterocyclic carbenes (NHCs) (1) continue to be popular ligands in homogeneous catalysis. (2) In particular, copper NHC complexes have been attractive as catalysts in a wide variety of reactions [...]

Asymmetrical flow field-flow fractionation (AF4) coupled with UV-vis spectrophotometry, multiangle light scattering (MAILS), and dynamic light scattering (DLS) detection was used to analyze dispersions of DNA/ rhodamine B labeled chitosan (Ch-rho) complexes frequently used as gene delivery vectors. The method yielded, in a single experiment, important characteristics of the complexes, such as their hydrodynamic radius, size distribution, conformation, composition, and the amount of free Ch-rho in the dispersions. Samples for analysis were obtained by varying experimental parameters known to influence the transfection efficiency of DNA/chitosan complexes, including the DNA concentration at mixing (82-164 [micro]g/mL), the ratio of chitosan amino groups to DNA phosphate groups (3 [less than or equal to] N/P ratio [less than or equal to] 15), the chitosan molecular weight (10-76 kDa), and its degree of deacetylation. In all preparations, DNA/Ch-rho complexes had hydrodynamic radii ranging from 15 to 160 nm. Both the DNA concentration and the Ch-rho molecular weight influence the size distribution of the complexes: a greater fraction of large particles was detected in dispersions prepared with the most concentrated DNA solution or the Ch-rho of highest molar mass. All dispersions contained free Ch-rho in solution. The free Ch-rho content ranged from 53 to 92% of the total Ch-rho concentration in dispersions prepared with N/P ratios from 3 to 15, respectively, implying that the N/P ratio of the complexes ranged from 1.3 to 1.6 in all samples. The accuracy of the free Ch-rho determination by AF4/UV-vis/MALS+DLS was confirmed by an independent method involving (1) ultracentrifugation of the dispersions prepared with unlabeled chitosan and (2) analysis of the supernatant by the Orange II dye depletion method. This study demonstrates the ability of AF4/UV-vis/MALS+DLS to provide a complete physicochemical characterization of DNA/polycation complexes used in nonviral gene delivery. 10.1021/ac100711j

Several studies have described the synthetic preparation of Sb(V) complexes with organic ligands, but only recently was such a complex identified to exist in beverages stored in PET containers. In the present study, we have investigated by using HPLC--ICPMS and HPLC--ES-MS(/MS), the formation of Sb(V) complexes in various biological (urine) and food matrixes (yoghurt and juice) spiked with noncomplexed inorganic Sb(V). Our results show that Sb(V) complex formation is matrix dependent and that several Sb(V) complexes form to a considerable extent in these matrixes. The results also suggest that the existence of Sb(V) complexes in natural samples may have previously been overlooked due to analytical method limitations, mainly chromatographic, but also detection limitations when hydride generation is used. To overcome some of these limitations, we have developed chromatographic methods suitable for preserving Sb--organic ligand complexes during their separation. When applying this mild nondestructive chromatographic method, we were able to identify novel Sb complexes in yoghurt spiked with inorganic Sb(V), i.e., 1:1 Sb(V--citrate, 1:1 Sb(V)--lactate, 1:2 Sb(V)--lactate, and other Sb(V)--lactate complexes. This is the first characterization of Sb(V)--lactate complexes. Detailed studies on the hydride generation (HG) efficiency of Sb(V) complexes showed that Sb(V) complexes of high stability, such as Sb(V)--citrate, Sb(V)--[(adenosine).sub.n], and Sb(V)--[(lactate).sub.n], (n = 1 or 2), are nondetectable by HG-ICPMS. Furthermore, Sb(V) complexes formed in natural biological and food matrixes were only partly detectable by HG-ICPMS, confirming limitations of analytical methods based on HG volatilization and subsequent stibine detection in natural samples containing complexing ligands with affinity toward Sb(V).

Gel-Permeation Chromatography (GPC) can be used in the determination of size and purity of transition-metal-directed supramolecular assemblies (TMDSA), as well as in the deduction of byproducts in the syntheses of these materials. It is found that preparatory GPC can be used in the purification of mixtures of TMDSA.