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Novel materials for NLO applications based on guanidine derivatives - crystal engineering and detailed characterisation
Kohúteková, Soňa ; Němec, Ivan (advisor) ; Kalbáč, Martin (referee) ; Vlčková, Blanka (referee)
Title: Novel materials for NLO applications based on guanidine derivatives - crystal engineering and detailed characterisation Author: Mgr. Soňa Kohúteková Department: Department of Inorganic Chemistry Supervisor: prof. RNDr. Ivan Němec, Ph.D. Abstract: This doctoral thesis is focused on the preparation and characterisation of new compounds for potential application in nonlinear optics (NLO). Four molecules containing guanidine fragment were chosen as the carriers of NLO properties - aminoguanidine, diaminoguanidine, N-guanidine-formamide and 1H-pyrazole-carboxamidine, according to the promising preliminary results of hyperpolarizability values obtained by quantum-chemical calculations. Experimental work was divided into two main directions of preparation of new crystalline materials - preparation of perovskite metal-organic frameworks (MOFs) and molecular crystals. In the first group of studied materials, target molecules were expected to occupy cavities of frameworks built by formate anions coordinated to metal cations. In the second group, in the molecular crystals, carriers of NLO properties were co-crystallised with selected inorganic anions to prevent the formation of centrosymmetric dimers and to influence the desired crystal packing. Prepared materials were characterised mainly by the means of...
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Macrocycles and complexation of large metal cations
Faltejsek, Jan ; Hermann, Petr (advisor) ; Drahoš, Bohuslav (referee)
In the last years, radioisotopes of heavy elements from the bottom of the Periodic Table have been increasingly used in nuclear medicine with focus on alpha-therapy. These large metal ions demand ligands fulfilling their special requirements. Complexes of polyazamacrocyclic ligands have been used in radiomedicine for a long time as diagnostic and therapeutic agents. This work aims to con- tribute to understanding of coordination chemistry of large macrocycles toward large metal ions. Thus, this work deals with structural studies, formation and decomplexation kinetics of Ln(III)-H4pyta complexes employing X-ray solid-state and solution NMR/UV-Vis spectroscopic data. The H4pyta is a 18-membered hexaazamacrocycle formed by two pyridine units and four amine groups which are modified with four acetate pendant arms. In the solid state, several isomeric complexes were structu- rally characterized. Large Ln(III) ions form decacoordinated species with two and two acetates on each side of the macrocyclic N6-plane. Small Ln(III) binds the ligand in a nonadentate fashion with one pendant non-coordinated. In the middle of lanthanide series, both isomers were characterized for several Ln(III) ions. Formation of the complexes takes place in a three-step mechanism with fast formation of an out-of-cage intermediate...
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Potential contrast agents for MRI based on manganese(II) complexes
Drahoš, Bohuslav ; Lukeš, Ivan (advisor) ; Geraldes, Carlos F. G. C. (referee) ; Toth, Imre (referee)
The thesis is focused on the synthesis and characterization of novel Mn2+ complexes as alternative to Gd3+ chelates which are wide-spread contrast agents in Magnetic Resonance Imaging (MRI). In the perspective to find suitable chelators of Mn2+ , three groups of pentadentate ligands with different size of macrocylic cavity, different donor atoms and number of pendant arms containing various functional groups have been investigated. Coordination numbers of 6 or 7 were found in the crystal structure of the Mn2+ complexes enabling binding of one or two water molecules in the first coordination sphere. The direct water coordination causes a decrease in the complex stability and thus, the thermodynamic stability of investigated chelates is lower than that of polyaminocarboxylate complexes and their dissociation is very fast in comparison to [Mn(nota)] and [Mn(dota)]2- . The studied Mn2+ complexes do not undergo oxidation in air except for complexes with 12-membered ligands which are oxidized to Mn3+ species. The proton relaxivities of the bishydrated complexes are two times higher than those for monohydrated complexes and are comparable to those of commercial contrast agents based on Gd3+ complexes. Variable-temperature 17 O NMR data revealed that the water exchange varies from slow to intermediate or...
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