Application of capillary zone electrophoresis (CZE) to the determination of pathogenic bacteria for medical diagnosis

Microorganisms like bacteria, viruses, fungi, etc. have a major impact on human, animal, and plant life. Several decades ago it was observed that intact cells suspended in an isotonic salt solution moved toward the anode and the mobility was proportional to the density of the charge located on the cell surfaces. Since then, efforts have been made to make electrophoresis a useful tool in cell studies. Microorganisms are no exception. In the present work we applied the capillary zone electrophoresis (CZE) with dynamical modification of the capillary surface for separation of E. coli and P. vulgaris. The same method was used for identification of E. coli in infected urine (direct injection - UTIs) and also for identification of Helicobacter pylori which is a gram-negative bacillus responsible for one of the most common infections found in humans worldwide. Using spectrophotometric measurements at λ = 214 nm we proved that it is possible to measure the concentration of bacterial cells up to 5 × 10⁸ cells/mL. Recent studies have demonstrated very practical uses for electrophoretic techniques, especially in the field of medical diagnosis. Figure The developed CZE method allows the rapid analysis and identification of pathogenic bacteria: example shown illustrates the identifcation of E. coli in a urine sample determined much more rapidly than with conventional culturing on Petri dishes Presented at the 11th International Conference on Chemistry and the Environment, 9–12 September 2007, Torun, Poland.     

Stereoselective Construction of Tertiary Homoallyl Alcohols and Ethers by Nucleophilic Substitution at Quaternary Carbon Stereocenters

An efficient method for the stereoselective construction of tertiary C−O bonds via a stereoinvertive nucleophilic substitution at the quaternary carbon stereocenter of cyclopropyl carbinol derivatives using water, alcohols and phenols as nucleophiles has been developed. This substitution reaction proceeds under mild conditions and tolerates several functional groups, providing a new access to the stereoselective formation of highly congested tertiary homoallyl alcohols and ethers.     

Mechanistic Insights into the Synthesis of [Rh(acac)(CO)(NHC)] (NHC=N-heterocyclic carbene) Complexes Using a Weak Base

A simple synthetic method to access a wide range of [Rh(acac)(CO)(NHC)] complexes is described. In situ infra-red monitoring provides insights into the mechanism of the reaction, including the identification of a key intermediate. An understanding of the reaction mechanism leads to the discovery of novel pathways to commonly used congeners.     

Simplex Optimized LC Analysis of Plant Coumarins and Furanocoumarins

Sequential simplex methods are common and efficient optimization techniques applied in analytical chemistry. This study reports on the optimization of LC separation of coumarins using a variable-size simplex algorithm. The solvent systems consisted of methanol, water and tetrahydrofuran. Using an optimized method, seven standard simple coumarins and furanocoumarins derived from plants were successfully separated in one chromatographic run. The mobile phase at the point corresponding to the optimum consisted of 34% MeOH, 59% H₂O and 7% THF. Applying a solvent mixture in this proportion permitted separation of all critical pairs, such as esculetin/scopoletin, scopoletin/umbelliferone, umbelliferone/coumarin and xanthotoxin/psoralen. The retention ratio factors k for coumarins at the optimum of the simplex algorithm lay in the range 1 < k < 4. The optimal conditions assigned to the coumarin standards were then applied to the plant matter: herb of the rue (Ruta graveolens L., Rutae herba), anthodium of the camomile (Chamomilla recutita L., Chamomillae anthodium), herb of the southernwood (Artemisia abrotanum L., Abrotani herba), and radix of the lovage (Levisticum officinale K., Levistici radix). The validity of the method was confirmed with respect to these samples.     

Easily prepared chiral scorpionates: tris(2-oxazolinyl)boratoiridium(i) compounds and their interactions with MeOTf

Optically active C 3-symmetric monoanionic ligands are uncommon in organometallic chemistry. Here we describe the synthesis of readily prepared tris(4 S-isopropyl-2-oxazolinyl)phenylborate [To (P)] and fluxional, zwitterionic four- and five-coordinate iridium(I) compounds [Ir(To (P))(eta (4)-C 8H 12)] ( 4) and [Ir(To (P))(CO) 2] ( 5). The highly fluxional nature of 4 and 5 makes structural assignment difficult, and the interaction between the iridium(I) center and the [To (P)] ligand is established by solid-state and solution (15)N NMR methods that permit the direct comparison between solution and solid-state structures. Although iridium cyclooctadiene 4 is a mixture of four- and five-coordinate species, the dicarbonyl 5 is only the five-coordinate isomer. The addition of electrophiles MeOTf and MeI provides the oxazoline N-methylated product rather than the iridium methyl oxidative addition product. N-Methylation was unequivocally proven by through-bond coupling observed in (1)H- (15)N HMBC experiments.     

A new family of spin-crossover complexes based on a FeII(tetrazolyl)4(MeCN)2-type core

A bitopic ligand 2-hydroxy-1-(tetrazol-1-yl)-3-(tetrazol-2-yl)propane (12pbtzOH) was synthesized and reacted with Fe(ClO4)(2).6H2O, giving a 1D coordination polymer {[Fe(12pbtzOH)2(CH3CN)2](ClO4)(2).2CH3CN} infinity that exhibits a high-spin to low-spin transition (T1/2(downward arrow)=T1/2(upward arrow) congruent with 104 K). This is an unprecedented example of an iron(II) complex containing Fe(tetrazolyl) 4(MeCN)2 cores.     

Advantages and limitations of the synchrotron based transmission X-ray microscopy in the study of the clay aggregate structure in aqueous suspensions

This paper reports new application of new transmission X-ray microscopy powered by a synchrotron source for the study of aqueous based clay suspensions. This paper delineates the advantages and limitations of this method. The tested transmission X-ray microscopy (TXM) technique has shown good agreement with the cryo-stage SEM technique. The spacial resolution of this TXM technique is 60 nm and clay particles with diameter below 500 nm are clearly visible and their pseudohexagonal symmetry is recognizable in detail. It is clearly demonstrated the methodology of implementing TXM to study aqueous based clay suspensions that are close to approximately 60 nm tomographic resolution. The technique enables us to study discrete structure of clay suspensions in water and within aggregates. This has never been previously possible. Larger crystals, more compact aggregates and less colloidal fraction present in kaolinite from Georgia has impact on faster settling and gelling in denser suspension than for Birdwood kaolinite in which colloidal particles create gel-like networking in less dense aqueous suspension.     

Enantioselective 1,3‐dipolar cycloaddition reactions using complexes of (−)‐sparteine

Regio‐ and stereoselective 1,3‐dipolar cycloaddition of nitrile oxides to internal 2‐pentenols and α,β‐unsaturated esters catalyzed by (?) sparteine‐lanthanide complexes affords corresponding 3‐aryl‐2‐isoxazolines with enantioselectivities up to 68% ee.     

Glycoluril dimers bearing hydrogen atoms on their convex face and their self-assembly in the solid state

A selective method for the synthesis of 1,6-substituted glycolurils has been developed. The glycolurils have been used for the synthesis of methylene-bridged glycoluril dimers bearing hydrogen atoms on their convex face. Depending on the side walls of the dimers, different modes of self-assembly in the solid state have been described using X-ray crystallography.     

Diastereoselective synthesis of carbapenams via Kinugasa reaction

A facile approach to carbapenams via Kinugasa reaction between terminal copper acetylides and nonracemic cyclic nitrones derived from malic and tartaric acid is reported. The stereochemical preferences observed in these reactions are explained. The reaction provides an entry to the carbapenams basic skeleton.