Cyclometalated Iridium(III) Complexes Containing Semicarbazone Ligands: Synthesis,Characterization, Photophysical and Biological Studies

The synthesis, crystal structure, photophysical properties, and biological activity of the novel bis‐cyclometalated complexes [Ir(ptpy)₂(vnsc)] ( 2 ) and [Ir(ptpy)₂(acsc)] ( 3 ) [ptpy = 2‐(p‐tolyl)pyridinato, vnsc = vanillin semicarbazone, acsc = acetone semicarbazone] are described. The new compounds were prepared by the reaction of [{Ir(μ‐Cl)(ptpy)₂}₂] ( 1 ) with the corresponding semicarbazone ligands under basic conditions. The molecular structure of compound 3 was confirmed by a single‐crystal X‐ray diffraction study. The complex crystallized from chloroform as a mono‐ solvate in the orthorhombic space group Pcab with eight molecules in the unit cell.     

New approach to the determination phosphorothioate oligonucleotides by ultra high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry

This text presents a novel method for the separation and detection of phosphorothioate oligonucleotides with the use of ion pair ultra high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry The research showed that hexafluoroisopropanol/triethylamine based mobile phases may be successfully used when liquid chromatography is coupled with such elemental detection. However, the concentration of both HFIP and TEA influences the final result. The lower concentration of HFIP, the lower the background in ICP-MS and the greater the sensitivity. The method applied for the analysis of serum samples was based on high resolution inductively coupled plasma mass spectrometry. Utilization of this method allows determination of fifty times lower quantity of phosphorothioate oligonucleotides than in the case of quadrupole mass analyzer. Monitoring of ³¹P may be used to quantify these compounds at the level of 80 μg L⁻¹, while simultaneous determination of sulfur is very useful for qualitative analysis. Moreover, the results presented in this paper demonstrate the practical applicability of coupling LC with ICP-MS in determining phosphorothioate oligonucleotides and their metabolites in serum within 7 min with a very good sensitivity. The method was linear in the concentration range between 0.2 and 3 mg L⁻¹. The limit of detection was in the range of 0.07 and 0.13 mg L⁻¹. Accuracy varied with concentration, but was in the range of 3%.     

Mind the correct basis set: A case study for predicting gas phase acidities of small compounds using calculations from first principles

Some of the most popular computational methods have been utilized to determine a dependency of the acidity trend of the first‐row hydrides on a choice of basis set. For about three decades, methyl anion ( ) was known as the strongest base but after Tian et al. were able to produce the gas phase lithium monoxide anion (LiO–) they discovered it was a stronger base than (Tian et al., Proc Natl Acad Soc USA 2008, 105, 7647). Furthermore, the authors confirmed their experimental results using high‐level ab initio methods, namely W1 and W2C composite methods, as well as complete active space‐averaged quadratic coupled cluster and Brueckner Doubles with triple excitation contribution (BD(T)) within the aug‐cc‐pVQZ basis set. These methods are highly demanding in terms of the computational effort as well as a level of expertise needed from the user to correctly conduct such calculations. We have shown that the proper acidity trend, that is, , can be obtained with less expensive, ”black‐box” type methods if only the basis set is properly chosen. Our results prove that the diffuse augmented basis sets are absolutely necessary for appropriate predictions of acidities. Our calculations show that the correct order of is achieved by augmenting relatively small cc‐pVXZ (X = D,T) basis sets. A similar effect is observed for the family of Pople's basis sets. Our estimate for with CCSD(T)/aug‐cc‐pVTZ was 423.8 kcal/mol, which agrees very well with the experimental value 425.7 ± 6.1 kcal/mol. An important finding is that the proper acidity trend may be reversed if the basis sets are not correctly selected. © 2014 Wiley Periodicals, Inc.     

Trace metal analyses in honey samples from selected countries. A potential use in bio-monitoring

Honey is a sweet product made by bees using nectar from flowers. Concentrations of Ca, K, Mg, Fe, Zn, Mn, Cu, Pb and Cd were determined in 13 honey samples from the selected regions around the world. Levels of Ca, Mg, Cu, Fe, Zn and Mn were measured using flame atomic absorption spectrometry (FAAS). Potassium concentration was determined via flame photometry. Concentrations of Cd and Pb were determined using the electrothermal technique (ETAAS). It was estimated that the examined samples of honey from Greece, Turkey, Spain, Poland, Mexico, Argentina and Italy were of good quality in terms of metal concentrations (compliant with the norms referring to food products – WHO, Fifty-third Report of the joint FAO/WHO Expert Committee on Food Additives; Technical Report Series 776, Geneva), although the analysed samples were not free of heavy metals. The concentrations of the elements in the honey samples ranged from 2.38 to 9.31 μg · g^?1 for Zn, from 3.86 to 35.10 μg · g^?1 for Fe, from 0.19 to 21.64 μg · g^?1 for Mn, from 49.53 to 1006.90 μg · g^?1 for Ca, from 388.25 to 4761.50 μg · g^?1 for K and from 0.20 to 1.53 μg · g^?1 for Cu and regarding heavy metals from 0.11 to 2.78 μg · g^?1 for Pb and from 0.02 to 0.44 μg · g^?1 for Cd. According to these results it was found that the concentrations of heavy metals in the honey samples (except for alfalfa honey and eucalyptus honey from Italy) were under the acceptable limits for foods set out by the FAO/WHO. It was confirmed that the application of chemometric tools supports the extraction of significant information from analytical data, even though the availability of samples is not fully sufficient (this problem is often encountered in environmental analyses).     

Structural and thermal characterization of copper(II) complexes with phenyl-2-pyridylketoxime and deposition of thin films by spin coating

Four copper(II) oxime complexes, [Cu(HPPK)(PPK)X] (HPPK = phenyl-2-pyridylketoxime and X = CI^? (I), CF₃COO^? (II), C₃F₇COO^? (III), and [Cu(PPK)₂]₂ (IV)), were synthesized and characterized by elemental analysis, infrared spectroscopy (IR), and single-crystal X-ray diffraction (XRD). XRD analysis revealed that I–III contain copper(II) coordinated by four nitrogen atoms from two oxime molecules in the basal plane and one monodentate anion X in the apical position of a distorted square pyramid. Complex IV is dimeric and it is formed by two Cu(PPK)₂ units. Bridges between these units are formed by the two oxygen atoms of the deprotonated oxime groups. Thermal stability of I–IV was investigated by thermogravimetric analysis (TGA) in air and in nitrogen atmosphere, respectively. Evolved gaseous decomposition products were characterized by IR. I–IV decompose via multistep processes. Fluorocarbons and CO₂ were observed to be the most abundant gaseous species evolved. Preliminary ammonolysis experiments were performed to examine the possibility of using II and IV as precursors for the synthesis of copper nitride. Moreover, solutions of IV were spin-coated onto silicon substrates. Surface structure and morphology of the resulting films were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) and layers with island-like distribution of material were observed.     

Selective catalytic oxidation of ammonia into nitrogen and water vapour over transition metals modified Al<Subscript>2</Subscript>O<Subscript>3</Subscript>, TiO<Subscript>2</Subscript> and ZrO<Subscript>2</Subscript>

Copper or iron supported on commercially available oxides, such as γ-Al₂O₃, TiO₂ (anatase) and monoclinic tetragonal ZrO₂ (mt-ZrO₂) were tested as catalysts for selective catalytic oxidation of ammonia into nitrogen and water vapour (NH₃-SCO) in the low temperature range. Different commercial oxides were used in this study to determine the influence of the specific surface area, acidic nature of the support and crystalline phases as well as of the type of species and aggregation state of transition metals on the catalytic performance in selective ammonia oxidation. Copper modified oxide supports were found to be more active and selective to nitrogen than catalysts impregnated with iron. Activities of both transition metal modified samples decreased in the following order: mt-ZrO₂, TiO₂ (anatase), γ-Al₂O₃. Quantitative total ammonia conversion was achieved with the Cu/ZrO₂ catalytic system at 400°C. Characterisation techniques, e.g. H₂-temperature programmed reduction, UV-VIS-diffuse reflectance spectroscopy, suggest that easily reducible copper oxide species are important in achieving high catalytic performances at low temperatures.