National Repository of Grey Literature 52 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
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.
Complexes of 1,4,7-triazacyclonane for nuclear medicine
Lebruška, Viktor ; Kubíček, Vojtěch (advisor) ; Schulz, Jiří (referee)
The use of metal isotopes for the study of tissues in the field of nuclear medicine is currently being developed. Metal isotopes are accumulated non-specifically in the body. Therefore, it is necessary for diagnosis and therapy to use suitable ligands, which form a thermodynamically stable and kinetically inert complex with the given metal ion, which can be attached to a suitable targeting group. Isotopes of gallium and copper are suitable for imaging od therapy. The cavity of the 1,4,7-triazacyclononane is suitable for the complexation of gallium, copper and some other metals with a small radius. However, the macrocycle itself does not form thermodynamically stable complexes, so the nitrogen atoms must be substituted by proper pendant arms, such as carboxylates. In recent years organic residues of phosphoric acids are also used. This work deals with substances that are derivatives of 1,4,7-triazacyclononane and contain phosphorus arms, which were studied in recent years. Keywords complexes, ligands, dissociation constants, stability constants
Radiolabeling of aluminum and gallium complexes with radioisotope 18F
Kuncová, Lucie ; Kubíček, Vojtěch (advisor) ; Vojtíšek, Pavel (referee)
The most widely used emitter in positron emission tomography is the fluorine isotope 18 F, which can bind to a number of atoms, and thus allows the formation of imaging agents for positron emission tomography. This work will summarize methods for labeling complexes containing aluminum or gallium as a central cation, which can serve as stable carriers of the positron emitter in a human body. Both of these elements have unique physical and chemical properties suitable for molecular imaging. Therefore the development of complex labeling, their structure, coordination environment and some applications in nuclear medicine will be described here.
Nanofiber membranes generating singlet oxygen with magnetic separation
Liška, Vojtěch ; Mosinger, Jiří (advisor) ; Kubíček, Vojtěch (referee)
This thesis focuses on the preparation and study of a new type of photoactive polyurethane nanofiber membrane with encapsulated 5,10,15,20-meso-tetraphenylporphyrin (TPP) photosensitizer and maghemite nanoparticles. The membrane was prepared by electrospinning and shows effective photogeneration of O2 (1 Δg) and photoantibacterial effect on the surface. The membrane can be easily separated by a magnetic field. The magnetic behaviour of the maghemite nanoparticles was studied using Mössbauer spectroscopy. Their size was estimated by DLS. The final nanofiber membrane was characterized by UV-VIS, emission spectroscopy, and by electronic microscopy (SEM). The kinetics of O2 (1 Δg) generation was studied by time-resolved spectroscopy and the relative efficiency of photooxidation was studied using external acceptor of O2 (1 Δg). Significant photoantibacterial properties against bacteria strain Escherichia coli were detected on the surface of the membrane functionalized with TPP photosensitizer.
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...
Complexes of 1,4,7-triazacyclononane derivatives
Kubinec, Jan ; Kubíček, Vojtěch (advisor) ; Vojtíšek, Pavel (referee)
The aim of this thesis was to prepare monoamide of macrocycle H3NOTA, which was prepared by multiple step synthesis. Ligand was characterized by NMR, MS and X-ray difraction analysis. Acid-base properties were studied by potentiometric titrations. Four protonation constants pKa`s were found and these protonation constants are lower than pKa`s of H3NOTA. Coordination properties with selected metal ions from the first row of transition metal, metal ions of biological interest and with lithium ions were investigated by potentiometric titration. Stability constants show that monoethylamide derivative of macrocycle H3NOTA forms complexes with lower stability than diethylamide derivative of macrocycle H3NOTA. Stability constants for complexes which contains amide group are lower than for H3NOTA complexes. Kinetics of Ga3+ complexation was investigated at different pH by 71 Ga NMR. The rate constants of and half-lives of complexation were determined at pH = 1. The rate constant was higher and the half-life of complexation was shorter than for H3NOTA ligand. Key words: macrocyclic complexes, thermodynamic stability, formation kinetics, radiopharmaceutical
Study of proton conductivity on powder samples
Nižňanský, Matěj ; Havlíček, David (advisor) ; Kubíček, Vojtěch (referee)
The focus of this thesis is the synthesis and characterisation of one newly prepared and one previously prepared compound which based on the results of x-ray structure analysis both contain systems of conveniently long hydrogen bonds. These systems potentially allow proton transfer through their structure. The results acquired by measuring proton conductivity of the newly prepared substance are also discussed in this thesis. Furthermore, it contains the results of the characterisation of both prepared substances by IR spectroscopy, powder x-ray diffraction and diffraction on monocrystal. The measurement of proton conductivity was carried out using tablets consisting of pressed powder samples which had gold-palladium alloy electrodes applied to them. The specific conductivity of these samples was determined by the measured electric resistance and the size of these tablets. Based on the conducted measurements, it can be stated that the newly synthesised substance does not exercise proton conductivity within the detection limit of used hardware, whereas the previously prepared one does. These results are further discussed in corresponding chapter considering primarily the structure of both substances.
Macrocyclic complexes with open coordination sphere
Jaroš, Adam ; Kubíček, Vojtěch (advisor) ; Gyepes, Róbert (referee)
The aim of this work was to synthesize and study acid-base and coordination properties of ligands bearing a neutral or negative charge on their pendant arms. Acid-base properties of two ligands and thermodynamic stability of their complexes with gallium, copper, and zinc ions were studied using potentiometry, UV-Vis and NMR. Solid state structure of one of the ligands and its complex with copper ion was studied using RTG structural analysis. Structure of complexes in solution was studied using methods of computational chemistry.

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2 Kubíček, Václav
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