The synthesis and reactions of a modified cobalt corrin

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Doctor of Philosophy. June 2018The typically inert Co(III) ion exhibits remarkable lability when encapsulated in a corrin macrocycle such as in vitamin B12. It has been postulated that this lability arises from a significant kinetic cis-effect through the delocalisation of electron density from the relatively electron-rich corrin to Co(III), thus conferring to it a degree of soft, labile Co(II)-like character. We suggest that structural and electronic modifications of the corrin should modulate the transfer of electron density to the central Co(III) ion, thus changing its electronic character. Another important feature of the corrin ring is the relatively small macrocyclic cavity. It appears that Co(III) may be compressed within the corrin macrocycle, which is likely to significantly impact its chemistry. To evaluate what effect these factors may have on the chemistry of Co(III), we prepared a vitamin B12 derivative, Coα,Coβ-dicyano-5,6-dioxo-5,6-seco-heptamethylcob(III)yrinate, [DC-5-seco-Cbs], by perturbing the electronic structure of the dicyanocobyrinic acid heptamethyl ester, Coα,Coβ-dicyano-heptamethylcob(III)yrinate ([DCCbs]) through a photosensitized oxygenation reaction. Not only does this disrupt the partially conjugated system of a normal corrin ring, but the bond between C5 and C6 has been cleaved such that the equatorial ligand of Co(III) is no longer macrocyclic, thereby relieving the steric constraints surrounding the axial coordination site of Co(III) corrins. The secocobester was then converted to the aquacyano derivative, Coα,Coβ-aquacyano-5,6-dioxo-5,6-seco-heptamethylcob(III)yrinate, [AC-5-seco-Cbs]+, in which a coordinated water could be readily displaced by an exogenous ligand in solution chemistry investigations. The effect of these structural modifications was evaluated by comparing analogous thermodynamic and kinetic data for [AC-5-seco-Cbs]+ with aquacyanocobyrinic acid heptamethyl ester (aquacyanocobester, [ACCbs]+), a corrin with an intact delocalised system (the values were re-determined in this study), and aquacyano-stable yellow-cobester, ([ACSYCbs]+), a corrin with a diminished delocalised π electron system, to observe the effect the nature of the corrin ring has on the properties of the Co(III) ion. The pKa for ionization of coordinated water decreases from 9.8 ± 0.3 in [ACCbs]+ to 7.28 at 25 oC (ΔH = –88 ± 17 kJ mol–1 and ΔS = –434 ± 56 J K–1 mol–1) in [AC-5-seco-Cbs]+. The unusually low pKa, confirmed by determining the pH-dependence of the coordination of SO32– by [AC-5-seco-Cbs]+, shows Co(III) in this complex behaves much more like Co(III) in simple hexacoordinate complexes than in intact cobalt corrins. A comparison of log K values the for coordination of CN–, SO22–, NO2–, N3– and S2O32– demonstrates that cleavage of the corrin ring significantly decreases the affinity of Co(III) for the softer ligands CN–, SO32– and, more marginally, NO2–. However, [AC-5-seco-Cbs]+ has a higher affinity for N3– and S2O32– than [ACCbs]+. These trends correlate with the position of the ligands in the spectrochemical series (N3– < S2O32– < NO2– < SO32– < CN–); the first two behave as π donors towards metal ions, and the last three as π acceptors. Cleavage of the corrin, with a concomitant increase in hardness of the metal, decreases it affinity for π acceptors while the thermodynamic stability of its complexes with π donors increases as the metal ion becomes more Co(III)-like, and more capable of accepting electron density from the ligand. The temperature-dependence of log K values show very negative values for ΔH offset by ΔS values which are also large and negative. In the absence of crystal structures, DFT methods (BP86-D3/6-311G(d,p)) were used to assess the structural consequences of cleavage of the corrin. The topological properties of the electron density were assessed using Bader’s Quantum Theory of Atoms in Molecules (QTAIM). The cleavage of the corrin does not unduly perturb the coordination sphere of the metal ion and the metal remains essentially octahedral. The sum of the partial charges on the metal and the entire coordination sphere, or the metal and the four equatorial donor N atoms, is less negative in the 5-seco-Cbs complexes than in the Cbs themselves and supports the supposition that cleavage of the corrin has made the metal and its immediate environment more positive. A brief look into the binding of neutral N-donor ligands (N-MeIm, 4-MePy and NH2EtOH) showed that the distinction between the softer Co(III) in [ACCbs]+ and the harder Co(III) in [AC-5-seco-Cbs]+ ([ACCbs]+ > [ACSYCbs]+ > [AC-5-seco-Cbs]+) observed for the binding of anionic ligands was maintained for the neutral N-donor ligands. Furthermore, results also indicated that relieving the steric hindrance surrounding the axial coordination site in [AC-5-seco-Cbs]+ did enhance the metal’s ability to bind larger neutral ligands. To probe the cis-labilising effect of the corrins, kinetics data for the substitution of water trans to a cyanide moiety with a probe ligand, cyanide, were obtained under pseudo first-order conditions. The substitution of water coordinated to Co(III) by cyanide showed biphasic kinetics. The faster reaction was attributed to substitution of H2O by CN– trans to CN–, and the slower phase to the reaction of the diaqua complex with CN–, i.e., substitution of H2O trans to H2O. The rate of substitution of H2O by CN– in [AC-5-seco-Cbs]+ is some two orders of magnitude slower than the substitution of H2O by CN– in [ACCbs]+. Cleavage of the corrin together with the release of Co(III) from the small cavity of the corrin has therefore significantly decreased the lability of Co(III). For interest, the data were compared to analogous data for aquacobalamin. In this way, the effect of the ligand trans to the axially coordinated water on its substitution could be elucidated. It was found that as the trans ligand varied from cyanide to dimethylbenzimidazole (DMBz) ([AC-5-seco-Cbs]+ to aquacobalamin), the rate constant increased from kII ≈ 102 M–1s–1 to 7.87 × 102 M–1s–1; hence cracking of the corrin ring and the associated opening of the macrocyclic cavity results in an even more pronounced inert Co(III) character. This study demonstrates how perturbation of the electronic structure of the corrin in cobalt corrin complexes significantly affects the coordination chemistry of the axial coordination sites and points to the importance of cis effects in cobalt corrin chemistry.MT 201

Kara śmierci w procesach o przestępstwa gospodarcze przed bydgoskim Wojskowym Sądem Rejonowym w świetle prasy lokalnej

During the initial postwar years, in the period of fight with the opposition and building of totalitarian system in Poland, criminal law instruments were widely used in order to fulfil the goals outlined by the new authorities, in both political and economic areas. Many drastic penalties were applied and military courts were involved in sentencing of civilians. The direction of the policy conducted in that time involved a high number of economic crime lawsuits, which were frequently described as “sabotage”, ascribed to representatives of management bodies of state-run enterprises. During functioning of the Military District Court in Bydgoszcz (1946-1955), more than a hundred “saboteurs” were sentenced and similar cases were handled by courts across Poland. The article presents three cases that were finalized in 1948, in which the Military District Court in Bydgoszcz passed the death sentence. Based on local newspapers and archival documents, cases described in detail involved Eugeniusz Smoliński, Director of the State Gunpowder Factory in Łęgnowo (later “Zachem”), Mieczysław Derwiński, Director of the State Fruit and Vegetable Processing Plant No. 19 in Fordon, and Stanisław Krzymin, Director of the State Telephone Exchange Factory No. 3 in Bydgoszcz (later “Telfa”). In the case of Eugeniusz Smoliński the sentence was executed, whereas in the remaining two cases the court commuted the sentence

Starting and running speed on the example of football clubs from Berlin

Currently, football is one of the most popular disciplines in the world. In the country of four-time World Champions, it is the most popular sport in which millions of fans and players are engaged. The German Bundesliga belongs to the Top 4 football leagues in Europe. Constant development of the discipline improves the training process. Shaping and developing selected motor skills seems to be necessary in modern training. In previous studies, many researchers emphasize the importance of motion speed in football. Nevertheless, the research conducted on a group of players of one German team in the 2017/2018 season raised some doubts.               Therefore, the study attempts to expand research and determine the relationship between start speed and running speed and the effectiveness of football games of German teams.              The research subject was 83 footballers from German clubs Berliner TSC and BSC Eintracht Südring Berlin. The results of studies carried out in Berlin in the 2017/2018 and 2018/2019 seasons were analyzed. The take-off speed in 5 m race, 20 m run speed was measured, and the players' effectiveness during the game was modified using the competent referee method. The test results were statistically processed in the Statistica 13.3 program. Descriptive statistics (X), minimum (min), maximum (max) and standard deviations (SD) statistics were performed and a correlation coefficient was determined.              In studies on an increased research group, no significant statistical relationship was found between motion speed and the effectiveness of German players' game

The level of Polish youth champions’ temperamental qualities in football

There are many factors which contribute to a successful sports career in football. One of the most important ones is players’ comprehensive preparation which consists of motor, technico-tactical and psychical components. The study focuses on a selected psychical aspect and more precisely on the temperamental features that describe and explain relationship between a man and environment.The aim of the study was to determine and compare the level of highly qualified young footballers’ temperamental properties in relation to those of the average people of the same age. The subject of the research was 31 players of the Lech Poznań club (Polish champions U-17 from 2016). The research was carried out using the EAS-D questionnaire which consists of five scales: dissatisfaction, fear, anger, activity and sociability.In the conducted study, there was a statistically significant differentiation of the results between the respondents and the average people at the level of two temperamental traits such as fear (a lower score in football players) and activity (a higher score in tested football players compared to the average people of the same age)

Verification of the Stormwater Drainage System Overloads in Wrocław for an Assessment of Climate Change Effects

This paper presents a verification of the performance of the stormwater drainage system in Gaj and Tarnogaj residential developments in Wrocław with regard to climate changes, by means of a calibrated hydrodynamic model created within the SWMM software. The verification was carried out for two criterial rainfalls: the Euler model rainfall with occurrence frequency C = 3 years and an actual rainfall with C = 5 years. Two parameters: degree of flooding (DOF) and specific flood volume (SFV) were adopted to indicate potential system overloads. The simulations showed numerous outflows from the sewers, which means, that the investigated system needs adapting to climate changes. The causes of this should be sought in the too small diameters of the sewers and so in the insufficient hydraulic capacity of the sewerage system dimensioned in the past using methods which are inadequate today