Dibutyl 2-(trifluoromethyl)cyclopropylboronate as a useful (trifluoromethyl)cyclopropyl donor: application to antagonists of TRPV1

Dibutyl-2-(trifluoromethyl)cyclopropylboronate 2, available in one step from commercially available reagents, serves as a useful (trifluoromethyl)cyclopropylating reagent by participating in a palladium-catalyzed Suzuki coupling. The use of boronate ester 2 in medicinal chemistry was exemplified by preparation of TRPV1 receptor antagonists.     

Suitability of ionic liquids as mobile‐phase additives in HPLC with fluorescence and UV detection for the determination of heterocyclic aromatic amines

The effects of several ionic liquids (ILs) as mobile‐phase additives in HPLC with fluorescence and UV–Vis detection for the determination of six heterocyclic aromatic amines were evaluated using two different C₁₈ stationary phases with moderate silanol activity. The studied ILs were 1‐butyl‐3‐methylimidazolium tetrafluoroborate, 1‐hexyl‐3‐methylimidazolium tetrafluoroborate and 1‐methyl‐3‐octylimidazolium tetrafluoroborate. The optical behaviour of heterocyclic aromatic amines in presence of ILs was studied and the silanol‐suppressing potency of ILs was evaluated for the two stationary phases studied. Several chromatographic parameters were evaluated in the presence or absence of ILs, or using triethylamine, the most common mobile‐phase additive. The best results were achieved using 1 mM 1‐butyl‐3‐methylimidazolium tetrafluoroborate as mobile‐phase additive and NovaPak^® column. In these conditions and with 18% of ACN in the mobile phase, analytical performance of the chromatographic methods using fluorescence and UV–Vis were evaluated, obtaining good precision in all cases (RSD lower than 6.6%) and low LOD (0.001–0.147 μg/mL with UV–Vis and 0.001–0.006 ng/mL with fluorescence detection).     

Solvent and salt effects on the kinetics of the reaction between [Ru(NH3)5pz]2+ and [Fe(CN)5H2O]3–

The kinetics of replacement of H₂O by [Ru(NH₃)pz]²⁺ (pz = pyrazine) in [Fe(CN)₅H₂O]^3? have been studied in various concentrated electrolyte solutions and in various water–cosolvent mixtures, at 298 K. Salt and cosolvent effects can be rationalized taking into account specific medium effects on both the encounter complex formation process and the ligand‐substitution process, once the encounter complex is formed. These effects in water–cosolvent mixtures depend on the solvation of the reactants by the components of the mixture, as well as on the solvent–solvent interactions in these mixtures. Salt effects seem to be related to a primary salt effect as well as to the effect of the cations on the electronic density on the iron complex. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 367–373, 2003     

Characterizing equivalent discrete Morse functions

We get a characterization theorem for equivalent discrete Morse functions defined on simplicial complexes in terms of their gradient vector field. As a consequence, we also characterize them in the 1-dimensional case by using critical elements. The authors are partially supported by the P.A.I. project (Junta de Andalucia, SPAIN, 2009/FQM-189 and 327) and by the MEC-FEDER grants MTM2007-61284 and MTM2007-65726 (MEC, SPAIN, 2007).     

Selective determination of acenaphthene in mixtures of three-ring polycyclic aromatic hydrocarbons by fluorescence quenching in micellar medium of cetylpyridinium bromide

The interaction of acenaphthene, anthracene, and phenanthrene with cetylpyridinium bromide (CPB) was studied. The CPB acts as a quencher provoking inhibition of fluorescence intensity emitted by these hydrocarbons. The existing differences in the fluorescence inhibition for these PAHs allow us to develop a selective synchronous spectrofluorimetric method for the determination of acenaphthene in a CPB micellar medium, with a detection limit of 9.2 and 10.4 ng ml^-1 for Δλ = 10 and 40 nm, respectively. The method was applied to the selective determination of acenaphthene in mixtures of typical three-ring hydrocarbons, including anthracene, phenanthrene, and fluorene.     

Urine 2DE proteome analysis in healthy condition and kidney disease

Urine is a source of potential markers of disease. In the context of renal disease, urine is particularly important as it may directly reflect kidney injury. Current markers of renal dysfunction lack both optimal specificity and sensitivity, and improved technologies and approaches are needed. There is no clear consensus about the best sample pretreatment procedure for 2DE analysis of the urine proteome. Sample pretreatment conditions spots resolution and detection sensitivity, critically. As a first goal, we exhaustively compared eight different sample cleaning and protein purification methodologies for 2DE analysis of urine from healthy individuals. Oasis® HLB cartridges allowed the detection of the highest number of low molecular weight proteins; while PD10 desalting columns resulted in the highest number of detected spots in the high molecular weight area. Sample pretreatment strategies were also explored in the context of proteinuria, a clinical condition often associated to renal damage. Testing of urine samples from 13 patients with hypertension or kidney disease and different levels of proteinuria identified Oasis® HLB cartridge purification in combination with albumin depletion by ProteoPrep kit as the best option for urine proteome profiling from patients with proteinuric (> 30 mg/L albumin in urine) renal disease.     

Foveal Pit Morphology Characterization: A Quantitative Analysis of the Key Methodological Steps

Disentangling the cellular anatomy that gives rise to human visual perception is one of the main challenges of ophthalmology. Of particular interest is the foveal pit, a concave depression located at the center of the retina that captures light from the gaze center. In recent years, there has been a growing interest in studying the morphology of the foveal pit by extracting geometrical features from optical coherence tomography (OCT) images. Despite this, research has devoted little attention to comparing existing approaches for two key methodological steps: the location of the foveal center and the mathematical modelling of the foveal pit. Building upon a dataset of 185 healthy subjects imaged twice, in the present paper the image alignment accuracy of four different foveal center location methods is studied in the first place. Secondly, state-of-the-art foveal pit mathematical models are compared in terms of fitting error, repeatability, and bias. The results indicate the importance of using a robust foveal center location method to align images. Moreover, we show that foveal pit models can improve the agreement between different acquisition protocols. Nevertheless, they can also introduce important biases in the parameter estimates that should be considered.     

Synthesis,characterization, and properties of new sequenced poly(ether amide)s based on 2‐(4‐aminophenyl)‐5‐aminobenzimidazole and 2‐(3‐aminophenyl)‐5‐aminobenzimidazole

A set of new aromatic poly(ether amide)s containing benzimidazole groups and ethylene oxide sequences of different lengths were synthesized and characterized. The new polymers were prepared from two benzimidazole diamines, 2‐(4‐aminophenyl)‐5‐aminobenzimidazole and 2‐(3‐aminophenyl)‐5‐aminobenzimidazole, and various oligo(ethylene oxide)dibenzoyl chlorides. They exhibited good solubility in polar aprotic solvents and glass‐transition temperatures in the range of 125–300 °C (the longer the ethylene oxide spacer was, the lower the glass‐transition temperature was). The new polyamides were essentially amorphous, as observed by X‐ray diffraction measurements and confirmed by differential scanning calorimetry measurements, by means of which no melting endotherm was observed in any case. The decomposition temperatures, as revealed by thermogravimetric analysis in nitrogen, were about 400 °C for all of them, regardless of the length of the ethylene oxide content or the phenylene ring orientation (meta or para) of the diamine moiety. The number of ethylene oxide linkages per repeat unit also determined the water uptake. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1414–1423, 2006