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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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Synthesis and Use of Transition Metal Complexes with Helical Ligands
Žádný, Jaroslav ; Vojtíšek, Pavel (advisor) ; Kotora, Martin (referee) ; Růžička, Aleš (referee)
The Thesis describes our successful endeavour to develop asymmetric synthesis of functionalized 2H-pyran or 2,7-dihydrooxepine helicene-like compounds in an optically pure form. These helicene surrogates were fully characterized and their use in enantioselective catalysis as chiral ligands, organocatalysts or chiral modifiers was explored. A general method for the preparation of optically pure [5]- and [6]heterohelicenes by asymmetric synthesis is based on highly diastereoselective [2+2+2] cycloisomerization of centrally chiral triynes mediated/catalyzed by transition metal complexes. Stereochemical outcome of the cyclization process is controlled by 1,3-allylic-type strain. This new methodology is highly versatile providing an easy access to chiral ligands, organocatalysts or modifiers in a nonracemic form. Optically pure 2,7-dihydrooxepine [5]helicene-like phosphite ligands were explored in enantioselective allylic amination under catalysis by iridium(I) complexes to reach up to 82% ee. An organocatalysts represented by the optically pure 2H-pyran [5]helicene-like DMAP analogue was synthesized and applied to kinetic resolution of racemic sulfoximines. Finally, various functionalized derivatives of helicenes and helicene-like compounds (azahelicenes, DMAP analogues, (thio)urea derivatives) were...
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MRI contrast agents for angiography
Urbanovský, Peter ; Kotek, Jan (advisor) ; Vojtíšek, Pavel (referee)
Modern diagnostic method magnetic resonance imaging (MRI) usually uses contrast agents T1-type, which are based on Gd3+ complexes. Due to severe toxicity of free Gd3+ , it is desired to have thermodynamically stable and kinetically inert complexes with fast elimination from the body. This work summarizes information about a novel contrast agent based on ligand DO3AP (1,4,7,10-tetraazacyclododecane-1-methyl(alkyl)phosphinic-4,7,10- triacetic acid) with pendant hydrophobic dibenzylamino group which is able to interact hydrophobically with the macromolecule of serum albumin. The stability of supracomplex is dependent on pH value, i.e. on the protonation of the pendant amino group of the complex (pKA = 5.6) and this interaction was confirmed from 1 H-NMRD profile and fluorescent analysis. The compound was tested for its angiographic properties in vivo on rat model. Furthermore, other complexes of the ligand with trivalent lanthanides (Nd3+ , Eu3+ , Tb3+ , Dy3+ , Er3+ ) were characterized by various methods (XRD, luminescence, UV-VIS, 1 H-, 17 O- and 31 P-NMR). The cleavage of the benzyl groups affords ligand whose Ln3+ complexes possess pH dependent PARACEST effect. These complexes were characterized by XRD, luminescence and 1 H- and 31 P-NMR. Moreover, the novel ligands with modified length of pendant...
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Porphyrine conjugates for MRI
Dušek, Pavel ; Vojtíšek, Pavel (advisor) ; Kotková, Zuzana (referee)
The theoretical part of this bachelor's thesis focuses on clinical applications of MRI methods. It also presents a list of gadolinium-based contrast agents used in clini- cal practice. A new conjugate of 1,4,7,10-tetraazacyclododecane-4,7,10-triacetate-1- {methyl-[(4-aminophenyl)methyl]phosphinic} acid and 5,10,15,20-tetrakis(4-amino- phenyl)porphyrin potentially active as a contrast agent is designed on the basis of this review. Due to unique properties of porphyrin unit, this compound may act as a bimodal contrast agent or contrast agent for functional imaging. The target compound and its ytterbium-complex were synthesized and partially characterized.
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New ligands for magnetic resonance imaging - pH-resposive contrast agents
Urbanovský, Peter ; Kotek, Jan (advisor) ; Vojtíšek, Pavel (referee)
Fast spread of MRI technique has brought new demands for MRI contrast agents. They are required to be nontoxic, kinetically inert, thermodynamically stable, biologically inactive complexes Gd(III) with high relaxivity (the ability of magnetic compounds to increase the relaxation rates of the surrounding water proton spins), removable from body in unchanged form. This bachelor thesis resumes basic theory for contrast agents, synthesis of new ligand and its Gd(III) complex coordinating one molecule of water and with ability of the non-covalent interaction of benzylic group with serum albumine resulting in increase in relaxivity. Luminiscence were measured for Eu(III) and Tb(III) complexes and relaxivity of Gd(III) complex in and without the presence of bovine serum albumine in vitro. The novel contrast agent was tested in vivo on rat model. Keywords MRI, gadolinium, macrocyclic ligands, macrocyclic complexes
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Electrochemistry of Nitrocalixarenes
Liška, Alan ; Vojtíšek, Pavel (advisor) ; Cibulka, Radek (referee)
In this diploma thesis a detailed investigation of the step-by-step reduction mechanism of cone-mono-, di-, tri and tetranitrocalix[4]arenes (in non-aqueous DMF) is presented. The intramolecular interaction of reducible (and reduced) centers and its consequences for the geometry of the starting molecule was discussed including the character of radicalic intermediates and their spin state. It was found, that the electrochemically generated radical anions of nitrogroups (unlike their starting electroneutral state) can act as ligands. Therefore, a study of complex formation equilibria of cone-tetranitrocalix[4]arenes with alkali metal cations followed. The possible use of a "stereoelectrochemical" approach (the relationship between geometry or conformation of the molecule and its electrochemical data) was demonstrated in describing and explaining conformational and electrochemical differences between two isomeric dinitrocalix[4]arenes. Finally, a new series of 1,3-alt-tetranitrothiacalix[4]arenes was electrochemically characterized and compared with the "classic" calixarene derivatives. Key words: electrochemistry, calixarenes, stereochemistry
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Cross-bridged cyclams as manganese(II) chelators
Míka, Luděk ; Kotek, Jan (advisor) ; Vojtíšek, Pavel (referee)
Title: Cross-bridged cyclams as manganese(II) chelators Autor: Bc. Luděk Míka Department: Department of Inorganic Chemistry, Faculty of Science Supervisor: doc. RNDr. Jan Kotek, Ph.D. Supervisor's e-mail address: modrej@natur.cuni.cz Abstract: The aim of this project was to synthesize a new kind of Mn(II) complexes with ligands derived from cross-bridged cyclam. These complexes may be potentially used as contrast agents in magnetic resonance imaging. Six macrobicyclic ligands with various pendant arm were synthesized, three complexes were sucesfully prepared. Electrochemical properties of prepared manganese(II) complexes with synthesized ligands were studied using cyclic voltammetry. Relaxivity of prepared complexes was determined by 1 H NMR spectroscopy. Keywords: cross-bridged cyclam, phosphonate, phosphinate, pendant arms, manganese
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Synthesis and properties of a ferrocenyl-substituted diphosphine
Verníček, Marek ; Štěpnička, Petr (advisor) ; Vojtíšek, Pavel (referee)
Title: Synthesis and properties of a ferrocenyl-substituted diphosphine Author: Marek Verníček Department: Department of Inorganic Chemistry (Faculty of Science, Charles University in Prague) Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. In this work, a new ligand was prepared, namely N,N-bis[2-(difenylfosfino)ethyl]amide of ferrocenecarboxylic acid. This ligand was obtained by the reaction of pentafluorophenylferrocenecarboxylate, which was newly synthesized, with the appropriate amine. The ligand was characterized by 1 H, 13 C, 31 P NMR spectroscopy, elemental analysis, IR spectroscopy and by mass spectrometry. Subsequently, a sulphide was prepared from this diphosphine-amide by the reaction with sulfur in toluene at elevated temperature. The sulphide was characterized in the same manner and also analyzed by single-crystal X-ray diffraction analysis. The coordination properties of the ligand were examined in a reaction with [PtCl2(cod)] (cod = cyclooctadiene) in dichloromethane. The resulting complex was studied by 1 H NMR, mass spectrometry, elemental analysis and by X-ray structural analysis. Keywords: ferrocene; phosphine ligands; amidophosphines; platinum(II) complexes; crystal structure.
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Study of thermodynamic stability of complexes with polydentate ligands
Böhmová, Zuzana ; Kubíček, Vojtěch (advisor) ; Vojtíšek, Pavel (referee)
Acid-base and coordination properties of macrocyclic ligand 1-oxa-4,7- diazacyclononane-4,7-bis(methylenephosphonic acid) were investigated. Protonation constants and stability constants with Ca2+ , Mg2+ , Cu2+ , Zn2+ , Mn2+ a Ga3+ metal ions were determined by potentiometry. Keywords Potentiometry, coordination chemistry, azacycles.
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