National Repository of Grey Literature 59 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Macrocyclic ligands for selective complexation of large cations
Šefčík, Martin ; Kotek, Jan (advisor) ; Vojtíšek, Pavel (referee)
4 Abstract Nowadays, macrocyclic complexes of actinides receive an increasing attention for their potential applications in radiotherapy. It requires significant demands on their thermodynamic and kinetic stability which are particularly influenced by an appropriate choice of a ligand. This Thesis focuses on a synthesis and characterization of two ligands that are potentially applicable for complexation of lanthanum as a model of radioactive actinium. Both ligands are based on a fifteen-membered cycle containing pyridine group, 15-pyN3O2. The first ligand, H4L1, contains two phosphonate pendant arms. The second ligand, H2L2, contains two phosphinate pendant arms. Both compounds were prepared and characterized. Keywords Macrocyclic ligands, large cations, phosphonic acids, phosphinic acids, dissociation constants
Complexes of polydentate ligands
Sedláčková, Simona ; Kubíček, Vojtěch (advisor) ; Kotek, Jan (referee)
Polydentate ligands are useful in many industries, mainly because of their ability to form complexes. The aim of this thesis is to study acid-base and coordination properties of polydentate ligands from the group of polyaminopolyphosphonates DTPMP and HMDTMP. The protonation constants of ligands as well as stability constants of complexes with biologically relevant ions Cu2+ , Zn2+ , Ni2+ , Mg2+ , Ca2+ , Co2+ , K+ and Na+ were determined by potentiometric titration. 31 P-NMR titration was used to determine pKa on nitrogen atoms, which could not be measured by potenciometric titration. Seven pKa for HMDTMP ligand and nine for DTPMP were obtained. The stability constants show that the HMDTMP ligand forms less stable complexes than the DTPMP ligand.
Cyclam derivatives with coordinating bifunctional groups in 1,8 positions for selective copper(II) complexation
Hörnerová, Alžběta ; Kotek, Jan (advisor) ; Vojtíšek, Pavel (referee)
Copper radionuclides are the object of increasing interest due to their advantageous properties for use in tumor diagnostics (PET, SPECT) and radiotherapy. In order to accomplish the best biodistribution the metal ion needs to be complexed by a suitable ligand attached to a biologically active molecule. The aim of this thesis is the synthesis of asymmetrically disubstituted derivatives of 1,4,8,11-tetraazacyclotetradecan (cyclam) with methylphosphonate and methylphosphinate pendant arms in 1,8 positions. Although the synthesis of designed ligands failed, the obtained knowledge will be used in further approaches of preparation of these compounds. Keywords: radiotherapy, SPECT, PET
Triazacyclononane derivatives bearing thiazole side group for anchoring to polymeric materials
Willimetz, Robert ; Kotek, Jan (advisor) ; Havlíček, David (referee)
With the growing resistance of bacteria to antibiotics, it is crucial to search for other ways to treat and prevent bacterial infections. Bacteria attached to the surface of medical implants can form a so-called biofilm, which is able to potentially cause the infection and subsequent health issues. The aim of this thesis was to prepare ligand capable of complexation of hydrolytically active metal ions, which would be able to cleave nucleic acids of bacteria. The selected ligand was 1,4,7-triazacyclononane derivative linked to thiazole side group for anchoring to polymeric materials. With these antibacterial polymeric substances it would be possible to coat the surfaces of the implants and therefore prevent developing of infections.
Vliv stárnutí populace na velikost deficitu státního rozpočtu České republiky
Kotek, Jan
Kotek, J. Influence of population ageing on the state budget deficit of the Czech Re-public. Bachelor thesis. Brno: Mendel University in Brno, 2017. Bachelor thesis is focused on the influence of population ageing on the state budget deficit of the Czech Republic. The aim of the bachelor thesis is to demonstrate the impact of the demographic development of the Czech Republic on the changes of the state budget deficit. Bachelor thesis is divided into three parts. The first part is theoretical. In the theoretical part is defined state budget, its functions, and the structure. The first part also includes explanation of demography. In the second practical part by regression model is demonstrated dependence between demo-graphic changes of the population and the size of the state budget deficit in the Czech Republic for the period 2000-2015. The last, final part, is focused on forecast of the future development of the examined phenomenon and its possible affecting.
Nanodiamonds coated with thermoresponsive paramagnetic polymers
Čopák, Jakub ; Kotek, Jan (advisor) ; Kubíček, Vojtěch (referee)
Temperature is a fundamental physical quantity referring to processes occurring in living systems. Therefore, it is important to design a thermometer which can measure the temperature in a real time and in nano-resolution. Fluorescent nanodiamonds, showing fluorescence thanks to nitrogen-vacancy pairs (NV centres) present as common crystal lattice defects, seem to be promising candidates. The NV centres are highly sensitive to magnetic field changes (magnetic noise). Paramagnetic metal ions reduce T1 relaxation time of nanodiamonds NV centres and this effect strongly depends on the distance between the metal ion and the NV centrum. Among all paramagnetic ions, Gd3+ is most suitable due to its high spin (7/2) and thus causes a great change in reduce T1 relaxation time. Thermoresponsive polymers can be used to achieve a distance change of the Gd3+ ion from nanodiamons NV centres. The aim of this thesis is the preparation of nanodiamonds coated with thermoresponsive paramagnetic polymer layer which can be further utilized as nanothermometer. The nanodiamonds were covered with a thermoresponsive polymeric layer containing a Gd3+ -containing monomer. This architecture responds to temperature changes in a geometric manner, altering the distance of Gd3+ ions from the NV centres. Keywords: nanodiamonds, NV...
Lanthanide complexes of DOTA-"trans"-diamide
Obuch, Jakub ; Hermann, Petr (advisor) ; Kotek, Jan (referee)
Macrocyclic complexes are of great interest due to their utilization in many medic- inal applications, such as MRI contrast agents and radiopharmaceuticals. These com- plexes overcome the toxicity of free heavy metal ions and, thus, enable their use in vivo. In this Thesis, diamide derivative of DOTA (tDODAM) and its lanthanide(III) complexes were prepared and characterised in solution and in the solid state. For cerium(III) com- plex, formation and dissociation kinetics were studied. Structure and dynamics of eu- ropium(III) complex were investigated by multinuclear NMR spectroscopy and various 2D NMR techniques. Similarly to Ln(III)-DOTA complexes, the complexes form square- antiprismatic (SA) and twisted-square-antiprismatic (TSA) isomers and their ratio in solution was determined across the lanthanide series. Structures of 7 lanthanide(III) complexes in the solid state were determined. Thermodynamic data were obtained for Cu(II), Zn(II), Pb(II), Ce(III), Eu(III) and Lu(III) complexes by potentiometric titration. 1
Coordination behaviour of substituted cyclen derivatives
Bárta, Jiří ; Kotek, Jan (advisor) ; Vargová, Zuzana (referee) ; Lubal, Přemysl (referee)
Magnetic resonance imaging (MRI) is one of the none-invasive techniques of human body examination. The only disadvantage of MRI is a low resolution and specificity, therefore, MRI contrast agents (CAs) are widely used in clinical practice (approximately in 40 % of all examinations). They increase not only resolution and specificity but also efficiency of the examination. The CAs consist of paramagnetic ion (Gd3+ or Mn2+ ) and strong chelator such as H4DOTA. Macrocycle cyclen (1,4,7,10-tetraazacyclododecane) is basis of many derivatives which are being used, including mentioned the H4DOTA ligand. 1,4-phosphonic or 1,4-phosphinic acid cyclen derivatives could be a better alternative to commercially available ones. In this thesis, a synthetic pathway to 5 of these novel derivatives is introduced. The protonation constants and stability constants with metals used in CAs (Mn2+ , Gd3+ ) and other selected ones using the potentiometric titrations are determined for 1,4-H4DO2P, 1,4-H2DO2POEt and 1,4-H2DO2Bn2PH . All three ligands have higher stability constant with Mn2+ - log KLM around 12, than with Ca2+ - log KLM around 8, which is the closest rival for transmetallation under physiological conditions. Strong Gd3+ -complex is formed by hexadentate ligand 1,4-H4DO2P - log KLM = 19.15, which is comparable...
Chelating Polymers for the Haemochromatosis Treatment
Groborz, Ondřej ; Hrubý, Martin (advisor) ; Kotek, Jan (referee)
5 Chelating Polymers for the Haemochromatosis Treatment Author: Ondřej Groborz Tutor: Mgr. Martin Hrubý, Ph.D., DSc. Advisors: Ing. Kristýna Kolouchová Ing. Pavel Švec Institute of Macromolecular Chemistry, Czech Academy of Sciences Abstract Haemochromatosis is a group of hereditary diseases which are characterised by toxic accumulation of iron in parenchymal organs, leading to organ toxicity and irreversible damage. Currently, there are only a few approved medications for this disease, yet all of them possess severe side effects. Herein, we have proposed a new paradigm for treatment: insoluble polymers with negligible systemic biological availability would form stable complexes with iron ions in the gastrointestinal tract, hence decreasing biological availability of iron. The insolubility of polymers prevents them from being absorbed into the organism in the first place while having no systemic side effects or toxicity. We have prepared polymers with several covalently bound iron-chelating ligands and based on the biological data we selected the most successful chelators for possible future applications. These polymers exhibited negligible resorbability and toxicity, superior in vitro iron chelating activity and their efficacy was proven in an in vivo model. Therefore they could be used as a...
Functional nanodiagnostics for 31-P magnetic resonance imaging: New paradigm for noninvasive imaging agents
Pechrová, Zdislava ; Hrubý, Martin (advisor) ; Kotek, Jan (referee)
The topic of my Master degree thesis is the development of a conceptually new class of contrast agents for the 31P magnetic resonance imaging (31P MRI). These agents are based on nanoparticles of calcium(II) phytate. Phytate (myo-inositol-1,2,3,4,5,6-hexakisphosphate) is largely present in plants, seeds and grains. It is non-biodegradable but nontoxic for animals and human beings and most importantly around 22% of its mass is phosphorus, so it is easily detectable by 31P NMR/MRI. These nanoparticles of Ca(II) phytate were doped with paramagnetic Fe3+ ions which broaden the 31P signal, making the nanoparticles invisible in healthy tissues. In the presence of bacteria producing siderophores (for example in Helicobacter pylori in gastric ulcers), Fe3+ is released from the gel and 31P MRI signal becomes detectable. In vitro simulation of this release was performed with deferroxamine, a compound possessing high affinity to Fe3+ ions forming coloured complex with it exploitable for the UV-VIS evaluation. The Ca(II) phytate can be synthesized in two possible ways. The first way is by direct precipitation of the Ca2+ salt with sodium phytate. The second way is ion exchange of phosphate in the nanoparticles of hydroxyapatite which creates electrostatically stabilized calcium phytate nanoparticles. Both...

National Repository of Grey Literature : 59 records found   1 - 10nextend  jump to record:
See also: similar author names
15 KOTEK, Jiří
2 Kotek, Jakub
1 Kotek, Jaroslav
15 Kotek, Jiří
1 Kotek, Josef
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