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Chemical and thermal stability of humic complexes
Nováková, Tereza ; Pospíšilová, Ľubica (referee) ; Klučáková, Martina (advisor)
The aim of this diploma thesis was the study of relation between chemical and thermal stability of complexes of humic acids with heavy metals, namely nickel, cobalt and copper. Complexes were prepared with metal solutions of three different initial concentrations. Through UV-VIS spectrophotometry were determined adsorbed amounts of incorporated metal ions in the structure of humic acid; it was affirmed that amount of bounded metal ions increases with increasing initial concentration. Chemical stability was determined as an amount of released metal ions, two of extraction agents were used (solution of MgCl2 and HCl), total bounded amount was distribute into three different fractions; residual fraction, strongly bound fraction and mobile and ion-exchangeable fraction. Changes that occured in the structure of humic acids after complexation and extraction were investigated by FT-IR spectrometry. Thermo-oxidative stability was tested through thermogravimetric analysis (TGA) and differential scanning calorimetry. The results of this diploma thesis has showed comparision of complexes of two different humic acids. They have confirmed an impact of each metal ion on thermo-oxidative stability of humic acids. The relation between chemical and thermal stability was compared through correlation of data obtained by these methods.
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Stability of complexes of humic acids with heavy metals
Nováčková, Kristýna ; Šmejkalová, Daniela (referee) ; Klučáková, Martina (advisor)
Tato diplomová práce je zaměřena na porovnání termo-oxidační a chemické stability kovových komplexů huminových kyselin. Pro tyto experimenty byly vybrány tři prvky reprezentující skupinu těžkých kovů (kobalt, měď a nikl). Použitá huminová kyselina byla extrahována z Jihomoravského lignitu. Pro přípravu komplexů byly využito různě koncentrovaných roztoků kovů, aby bylo možné pozorovat vliv jejich počáteční koncentrace na obě studované stability připravených komplexů. Chemická stabilita kovových komplexů byla posuzována z hlediska uvolňování kovových iontů ze struktury huminové kyseliny do dvou různých extrakčních činidel (HCl, MgCl2). Termo-oxidační chování bylo zkoumáno pomocí technik termické analýzy: diferenční kompenzační kalorimetrie (DSC) a zejména termogravimetrické analýzy (TGA). Výsledky této práce přinášejí hlubší poznatky o problematice interakce kovů s humifikovanou částí půdní organické hmoty, využitelné k osvětlení problematiky kovových polutantů v životním prostředí a prohloubení žádoucích znalostí procedur jako jsou dekontaminace půdy a remediace.
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Ditopic ligand based on 1,4,7-triazacyclononane
Kačmarčík, Jaroslav ; Kubíček, Vojtěch (advisor) ; Kotek, Jan (referee)
The radioisotopes 64 Cu and 68 Ga are used in radiomedicine and imaging (PET) due to their properties. The metal ion must be complexed with a suitable ligand forming a stable and kinetically inert complex. The aim of this bachelor thesis was to synthesize polydentate ligand based on the TACN macrocycle, followed by the preparation of its gallium (III) and copper (II) complexes. Based on the dependence of absorbance A on the wavelength λ, d-d transitions in the VIS (λ = 440 - 800 nm) region and CT transitions with transitions on the aromatic cycle in the UV region (λ = 220 - 380 nm) for the [Cu(L)] were also observed. The [Cu(L)] complex was studied by UV-VIS titration. The complex [Ga(L)] was also synthesized, but its further characterization and study of coordination properties were not carried out. Key words: macrocyclic ligands, complexes, stability, radiomedicine, PET
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Zirconium ternary complexes with fluoride anions
Zach, Kamil - Lukáš ; Kubíček, Vojtěch (advisor) ; Schulz, Jiří (referee)
Modern medicine uses non-invasive imaging methods for diagnostic purposes. Positron emission tomography is one of them. During the examination, the patient is injected with a radiopharmaceutical that is accumulated in tissue abnormalities and emits detectable radiation during its nuclear decay. The world's most commonly used radionuclide for these purposes is the radioisotope 18 F. The biodistribution of the fluoride ion itself is not very specific, so the radioisotope is usually bound to the structure of bioactive molecules. The actual preparation of these molecules is very challenging, so new labeling methods are currently being sought. One of the new possibilities is the preparation of labeled ternary complexes. In this work, the preparation of two polyazamacrocyclic ligands, H3NOTA and H3PCTA, which have acetate arms attached to their skeleton via aliphatic nitrogen atoms, is described. Zirconium complexes were prepared with these ligands. Subsequently, coordination and dissociation studies of fluoride ions to the prepared complexes were carried out. The measurements were monitored with a fluoride ion selective electrode. Both kinetic and thermodynamic aspects of coordination and decoordination were investigated in the measurements. Furthermore, characterization of the prepared ternary...
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Complexes of 1,4,7-triazacyclononane phosphinate derivatives
Lebruška, Viktor ; Kubíček, Vojtěch (advisor) ; Štěpnička, Petr (referee)
Phosphorus pendant arms accelerate the complexation of gallium(III) ions with macrocyclic chelators, which is crucial parameter in labelling by the radioisotope 68 Ga and their use in positron emission tomography (PET). In this thesis, new chelators for the selective complexation of gallium(III) ions were designed. Two chelators derived from the TACN macrocycle were prepared, namely: 1,4,7-triazacyclononane-1-methyl-methylene- bis(phosphinic) acid (H2L1 ) and 1,4,7-triazacyclononane-1-methyl-methylene- bis(phosphinato)-4,7-bis(methyl-phosphinic) (H4L2 ). The acidobase properties of the H2L1 were investigated using potentiometric and NMR titrations. Complexes of H2L1 with Ni(II), Cu(II), Zn(II) and Ga(III) were investigated using potentiometric titrations, which showed the high stability of these complexes. The solid-state structures of the Cu-L1 and Zn-L1 complexes were determined by X-ray diffraction. Complexation of the radioisotope 68 Ga(III) was studied for chelators H2L1 , H4L2 and for several related chelators with phosphorus pendant arms. The complexation study showed that chelators with the methylene-bis(phosphinate) pendant arm and some other phosphorus chelators derived from the TACN macrocycle accelerate complexation of gallium(III) ions. Using Dynamic PET scanning and ex-vivo...
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Dimer macrocyclic complexes
Rys, Jan ; Kubíček, Vojtěch (advisor) ; Vojtíšek, Pavel (referee)
This thesis is focused on dimer macrocyclic ligands and their complexes. Two dimer macrocyclic ligands based on ligand DO3A, linked with xylyl linker were prepared (BDO3A-p-X a BDO3A-m-X). Both synthetized ligands were characterized using NMR, MS, EA and in the case of BDO3A-p-X by X-ray crystallography. Data for calculating pseudo-first order reaction rates for complexations with Ce3+ metal ion and their pH dependency were obtained by use of UV/VIS spectrophotometry. Obtained data were compared to structurally close monomer ligand BnDO3A. Dimer ligands display different coordination properties based on proximity and position of coordinating cavities. Both prepared ligands behave differently than structurally close monomer ligand BnDO3A.
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Electrochemistry of macrocyclic complexes
Kaďorková, Veronika ; Liška, Alan (advisor) ; Kotek, Jan (referee)
The present thesis summarizes fundamental electrochemical properties of copper(II) complexes derived from three cyclame-like macrocyclic ligands. Target application of the studied complexes is radioimaging in medicine. The complexes were studied by means of DC-polarography and cyclic voltammery on mercury hanging drop electrode in buffered media (0.1M sodium acetate, pH 5) upon mixing of the ligand and copper(II) sulfate stock solutions. All three complexes undergo a single two-electron irreversible reduction process yielding free ligand and copper amalgam. The apparent thermodynamic stability of the investigated complexes (expressed as negative shift of the observed reduction potentials relatively to copper(II) sulfate) correlates to structural motifs employed in the individual ligand molecules. Presence of the bridged moiety as well as the carboxylate group seems to enhance the overall stability whereas the phenolic oxygen atoms in role of donor atoms seem to be less efficient.
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Responsive Contrast Agents for Magnetic Resonance Imaging (MRI)
Krchová, Tereza ; Kotek, Jan (advisor) ; Marek, Radek (referee) ; Platas-Iglesias, Carlos (referee)
ABSTRACT This work is focused on the synthesis of a family of new macrocyclic ligands with exchangeable protons on coordinating groups that could potentially serve (after complexation with suitable paramagnetic lanthanide(III) ions) as responsive contrast agents (CAs) for magnetic resonance imaging (MRI). It is expected that measurement of extracellular pH should bring information for tumorous disease diagnoses and/or for suggesting the most efficient treatment. Therefore, our attention was focused on pH-dependent CAs based on a PARAmagnetic Chemical Exchange Saturation Transfer (PARACEST) mechanism capable of reporting pH changes in tissue. The PARACEST-related properties of a series of Ln(III) complexes with the CEST effect caused by amino groups coordinated to the central Ln(III) metal ions were investigated. Such a kind of PARACEST CA is new and has had no precedent in the literature. It was shown that these Ln(III) complexes produce a pH-sensitive PARACEST effect in the pH region relevant for living systems. The study brings proof-of-principle for utilization of complexes with a linear diamine pendant arm, i.e. complexes with two exchanging proton pools, for ratiometric pH determination by MRI independently on the probe concentration. In addition, to ensure a higher kinetic inertness of the...
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Polydentate aminodiphosphinates
Böhmová, Zuzana ; Kubíček, Vojtěch (advisor) ; Vojtíšek, Pavel (referee)
Two linear aminodiphosphinates (H3L1 , H5L2 ) and one cyclic aminodiphosphinate (H2L3 ) were prepared and studied. Newly prepared compounds were characterized by NMR, MS and EA (elemental analysis). Acid-base and coordination properties of ligands were studied. Protonation constants and stability constants of complexes with Zn2+ , Ni2+ and Cu2+ metal ions were determined by potentiometry. Keywords Ligands, dissociation constants, potentiometry, phosphinates, complexes.
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