Trispyrazolylborate Ligands Supported on Vinyl Addition Polynorbornenes and Their Copper Derivatives as Recyclable Catalysts

Polynorbornenes prepared by vinyl addition polymerization and bearing pendant alkenyl groups serve as skeletons to support trispyrazolylborate ligands (Tp^x) built at those alkenyl sites. Reaction with CuI in acetonitrile led to VA-PNB–Tp^xCu(NCMe) (VA-PBN=vinyl addition polynorbornene) with a 0.8–1.4 mmol incorporation of Cu per gram of polymer. The presence of tetracoordinated copper(I) ions was been assessed by FTIR studies on the corresponding VA-PNB-Tp^xCu(CO) adducts, in agreement with those on discrete Tp^xCu(CO). The new materials were employed as heterogeneous catalysts in several carbene- and nitrene-transfer reactions, showing a behavior similar to that of the homogeneous counterparts but also being recycled several times maintaining a high degree of activity and selectivity. This is the first example of supported Tp^x ligands onto polymeric supports with catalytic applications.     

When a Red–NIR-Emissive Cs2[Mo6Br14] Interacts with an Active Diureasil–PEO Matrix: Design of Tunable and White-Light-Emitting Hybrid Material

Hybrid materials that combine diureasil matrices and octahedral molybdenum clusters have been synthesized to design lead-, cadmium- and rare-earth-free emitters for lighting or optoelectronic applications. This association leads to homogeneous and stable hybrids, for which the emission color can be tailored in the entire visible range, including white light; this is thanks to effective energy transfers from the host to the nanocluster.     

New synthesis of pyrazole and isoxazole derivatives

A convenient synthesis of 5-aryl-1-phenylpyrazoles and 5-arylisoxazoles, from readily available ketimine 1 dimethylformamide dimethylacetal and phenylhydrazine or hydroxylamine, is described.     

Frequency spectrum and confinement of optical radiation of nanorods in multilayered microsphere

The electromagnetic radiation of a quantum semiconductor nanorod (considered in a dipole model), placed into a multilayered microsphere with alternative spherical stack, is studied. We found that the frequency spectrum consists of series of narrow and well separated peaks even in a lossy case. In the band of such peaks the great part of the field energy is located in the structure of the stack and practically does not leave the microsphere. A possibility of resonant coupling of photon states in the area of nanorods is discussed.     

1,2,4,6-Tetraphenylpyridinium perchlorate as a reagent for ion-association complex formation and its use for the spectrophotometric determination of gold

The synthesis, characteristics, and applications of 1,2,4,6-tetraphenylpyridinium perchlorate (TPPP) as an agent that forms ion-association complexes is described. This new spectrophotometric analytical reagent forms with AuCl₄^?1 a 1:1 complex which is slightly soluble in water and can be extracted with isopentyl acetate, with maximum absorbance 313 nm, molar absorptivity 3.44 × 10⁴ liters mol^?1 cm^?1. The variables involved in the formation and extraction of the complex in the mentioned organic solvent are studied. In the selected conditions, 1 M hydrochloric acid medium, the extraction efficiency was 95.3%. The apparent stability constant of the complex is log K = 5.9 ± 0.1 at 20 °C. The extracted complex is useful for the spectrophotometric determination of gold in the range of 0.05 to 0.5 ppm. Standard deviation at 0.2 ppm (10 determinations) was 0.0022 and the relative error was ±0.78%.The interferences of many foreign ions are studied, concluding that the procedure proposed shows a high selectivity.The method has been applied satisfactorily to the determination of gold in ores, leads and other materials.     

Cobalt(II) complexes of 5,7-dimethyl[1,2,4]-triazolo-[1,5-a]-pyrimidine. Spectroscopic characterization,XRD study and antimicrobial activity

Summary Several cobalt(II) complexes of 5,7-dimethyl-[1,2,4]-tria-zolo-[1,5-a]-pyrimidine (DMTP) have been prepared and characterized by thermal and spectroscopic techniques. The crystal structure of [Co(DMTP)₂(H₂O)₄]Br₂·2H₂O has been determined by XRD; the metal ion is octahedrally coordinated by two DMTP ligands through the usual N(3) site and four water molecules. Metal binding to N(3) for DMTP is consistent with the electronic properties calculated with the MOPAC programme. All the complexes were screened for their activity against several types of bacteria, showing a broad-spectrum antimicrobial activity.     

Acoustic voice analysis in patients with Parkinson''s disease treated with dopaminergic drugs

To quantify several acoustic features of the voice in patients withParkinson's disease (PD), 41 patients and 28 age and sex-matched controls were studied. PD severity was assessed with the Unified PD Rating Scale (UPDRS) and the Hoehn and Yahr staging. The Computerized Speech Lab 4300 program (Kay Elemetrics) was used. Two seconds of a sustained /a/ and a sentence were captured with a microphone and laryngograph equipment. Measures included fundamental frequency (FO), frequency perturbation (fitter), intensity perturbation (shimmer), and harmonic/noise ratio (H/N) of the vowel /a/, and frequency and intensity variability of a sentence, phonational range, dynamic range at the natural frequency, maximum phonational time and s/z ratio. All subjects underwent indirect laryngoscopy and/or laryngeal fibroscopy. When compared with controls, PD patients showed higher jitter, lower H/N ratio, lower frequency and intensity variability of the sentence, and lower phonational range and reported a higher frequency of the presence of low voice-intensity, monopitch, voice arrests, and struggle. These features seem to be unaffected by the duration and severity of the disease.     

A Prussian blue-based flow-through renewable surface optosensor for analysis of ascorbic acid

Ascorbic acid is determined by a simple Bead Injection Spectroscopy–Flow Injection Analysis (BIS–FIA) system with spectrophotometric detection. The sensor is based on the decrease of absorbance obtained (720 nm) when Prussian blue (PB) is reduced by ascorbic acid. Commercial available flow-cell (Hellma 138-OS) is used and an appropriate volume of homogeneous bead suspension of Sephadex QAE A-25 was injected to fill this flow-cell for each measurement. The chromogenic reagent (PB) is injected into the carrier and immobilized on beads. When sample is injected, reaching the bead surface where PB is sorbed, ascorbic acid converts it to Prussian white form, which is transparent, producing the discoloration of the detection zone. At the end of the analysis, beads are discarded by reversing the flow and instantaneously transported out of the system.The calibration graph was linear over the range 5.1×10⁻⁶–6.8×10⁻⁵ M. The detection limit and RSD (%) were 4.5×10⁻⁷ M and 5.0%, respectively, using 800 μl of sample volume. This method is highly selective in the presence of other species that are normally encountered with the analyte. The sensor was applied satisfactorily to the determination ascorbic acid in fruit juices, pharmaceuticals, sweets and conservative liquids.