Synthesis,structure and antitumor activity of the binuclear tetranitrosyl iron complex with 2-mercaptobenzthiazole – the nitric oxide donor (NO)

Single-crystals of binuclear neutral sulfur-nitrosyl iron complex with 2-mercaptobenzthiazole ligand [Fe₂(С₇н₄NS₂)₂(NO)₄] (BTz) have been obtained. From X-ray data, BTz has a centrosymmetric dimeric structure, with the iron atoms being linked through the µ-N-C-S bridge. As follows from mass-spectra of the BTz gas phase, the complex is stable in the crystalline state under normal conditions (ambient temperature and standard humidity) and releases nitric oxide upon heating. Using amperometry, kinetics of NO release by BTz in 1% dimethyl sulfoxide aqueous solution has been studied: release of NO was shown to occur immediately upon dissolution in protic media. BTz inhibited growth of K562 leukemia and SKOV₃ ovarian carcinoma cells in vitro and induced apoptosis via activation caspases 3 and 7.     

On the heavy atom on light atom relativistic effect in the NMR shielding constants of phosphine tellurides

The relativistic HALA effect has been shown to depend on the spatial deformation of the lone electron pairs of a heavy atom, as demonstrated for alkyl and alkene phosphine tellurides. It was found that HALA effect on phosphorous nuclear magnetic resonance shielding constant is strongly dependent on the spatial arrangements of light substituents on phosphorus, resulting in the deformation of the lone electron pairs of tellurium.     

Long-range relativistic heavy atom effect on 1H NMR chemical shifts of selenium- and tellurium-containing compounds

Previously unknown manifestation of heavy atom effect on the NMR chemical shifts of β- and γ-protons initiated by the relativistic effects of the tellurium and selenium atoms has been investigated in the representative series of selenium- and tellurium-containing compounds. To approve the four-component density functional approach to be the appropriate tool for the investigation of the heavy atom on light atom effect (HALA), the benchmark calculations of the proton chemical shifts have been performed at the CCSD level using comprehensively chosen locally dense basis set with taking into account solvent, vibrational, and relativistic corrections. A good agreement with the experimental data was achieved. The magnitudes of the relativistic HALA corrections to β- and γ-proton chemical shifts were found to vary in a wide range, namely from −3.08 ppm for the γ-proton of methyltelluraldehyde to 14.51 ppm for β-proton in benzotelluraldehyde.     

Thermal and mineralogical investigations of historical ceramic

The selected sample for this study represents a piece of pavement ceramics from a private collection. The ceramic (approximately XVIIIth century) comes from Campania region, Naples province. A chemical, mineralogical and morphological characterization of a Campagna ceramic piece received from a particular collection has been performed. Inductively coupled plasma-atomic emission spectroscopy—(ICP-AES) was used for the determination of Al₂O₃, CaO, Fe₂O₃, K₂O, MgO, MnO, Na₂O, and TiO₂ as major constituents and Cu, Cr, Ni, Pb, and Zn as minor and trace selected elements. There is a very important characterization method used for the control of the reaction process and of the properties of the materials obtained. Physical and mineralogical analyses were made by using the thermal behavior (thermogravimetric analysis (TG) and differential thermal analysis (DTG)) and X-ray diffraction spectrometry for the mineralogical composition. The results of these analyses allow the establishment of conclusions about several aspects of their manufacture, the origin of the raw materials and their provenance (local or imported). They provide information supporting certain archeological hypothesis. The performed analysis revealed some very interesting characteristics: lower amount of silica and increased concentration of alumina, the presence of calcium in relatively low concentration (Ca-poor ceramic) and a mineralogical composition.     

Pd-catalyzed amination in the synthesis of cyclen-based macrotricycles

Three approaches to three types of cyclen-based macrotricycles have been elaborated starting from trans-bis(3-bromobenzyl)cyclen. The macrotricycles were synthesized via Pd-catalyzed amination. The first approach employed consecutive macrocyclization and benzylation steps giving a cage-like tricycle. In the second, cyclen amino groups were Boc-protected prior to formation of the second and the third rings. In the third method, macrotricycles were synthesized according to a one-step procedure using diazacrown ethers.     

Towards the 150th Anniversary of the Markovnikov Rule

The Markovnikov rule, known to every student of organic chemistry, was formulated 150 years ago, in 1869. During its long history (almost as long as the history of organic chemistry itself), attitudes towards this famous statement of chemical reactivity have evolved from indifference up to the 1930s, through common acceptance as a useful educational paradigm with marginal use in research up to the 1990s, to its vigorous relaunch as an important designation of regioselectivity in the last few decades. The unexpected new popularity of the classical rule is accounted for by the rapid expansion in catalytic addition reactions and their critical importance as highly effective atom‐economical, regioselective methods in modern organic synthesis. A historical outline of the life and achievements of Vladimir Markovnikov is included to reveal the very wide scope of his interests as well as his prophetic predictions on structure, reactivity, selectivity, stereochemistry, and other key issues of organic chemistry.     

MP2 calculation of 77Se NMR chemical shifts taking into account relativistic corrections

The main factors affecting the accuracy and computational cost of the Second‐order Möller‐Plesset perturbation theory (MP2) calculation of ⁷⁷Se NMR chemical shifts (methods and basis sets, relativistic corrections, and solvent effects) are addressed with a special emphasis on relativistic effects. For the latter, paramagnetic contribution (390–466 ppm) dominates over diamagnetic term (192–198 ppm) resulting in a total shielding relativistic correction of about 230–260 ppm (some 15% of the total values of selenium absolute shielding constants). Diamagnetic term is practically constant, while paramagnetic contribution spans over 70–80 ppm. In the ⁷⁷Se NMR chemical shifts scale, relativistic corrections are about 20–30 ppm (some 5% of the total values of selenium chemical shifts). Solvent effects evaluated within the polarizable continuum solvation model are of the same order of magnitude as relativistic corrections (about 5%). For the practical calculations of ⁷⁷Se NMR chemical shifts of the medium‐sized organoselenium compounds, the most efficient computational protocols employing relativistic Dyall's basis sets and taking into account relativistic and solvent corrections are suggested. The best result is characterized by a mean absolute error of 17 ppm for the span of ⁷⁷Se NMR chemical shifts reaching 2500 ppm resulting in a mean absolute percentage error of 0.7%. Copyright © 2015 John Wiley & Sons, Ltd.